Effect of gallium doping on electromagnetic properties of barium hexaferrite

Accepted Manuscript Effect of gallium doping on ectromagnetic properties of barium hexaferrite S.V. Trukhanov, A.V. Trukhanov, V.G. Kostishyn, L.V. Panina, An.V. Trukhanov, V.A. Turchenko, D.I. Tishkevich, E.L. Trukhanova, O.S. Yakovenko, L. Yu. Matzui, D.A. Vinnik PII:

S0022-3697(17)30876-4

DOI:

10.1016/j.jpcs.2017.07.014

Reference:

PCS 8132

To appear in:

Journal of Physics and Chemistry of Solids

Received Date: 22 May 2017 Revised Date:

22 June 2017

Accepted Date: 15 July 2017

Please cite this article as: S.V. Trukhanov, A.V. Trukhanov, V.G. Kostishyn, L.V. Panina, A.V. Trukhanov, V.A. Turchenko, D.I. Tishkevich, E.L. Trukhanova, O.S. Yakovenko, L.Y. Matzui, D.A. Vinnik, Effect of gallium doping on ectromagnetic properties of barium hexaferrite, Journal of Physics and Chemistry of Solids (2017), doi: 10.1016/j.jpcs.2017.07.014. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

EFFECT OF GALLIUM DOPING ON ECTROMAGNETIC PROPERTIES OF BARIUM

ACCEPTED MANUSCRIPT HEXAFERRITE

S.V. Trukhanov1, 2, 3 *, A.V. Trukhanov1, 2, 3, V.G. Kostishyn1, L.V. Panina1, An.V. Trukhanov1, 3, V.A. Turchenko4, 5, 6, D.I. Tishkevich3, E.L. Trukhanova1, 3, O.S. Yakovenko7, L.Yu. Matzui7, D.A. Vinnik2 1

National University of Science and Technology “ MISiS ”, Leninskii av., 4, Moscow, 119049

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Russia, *e-mail: [email protected]

Laboratory of single crystal growth, South Ural State University, Lenin av., 76, Chelyabinsk, 454080, Russia 3

Scientific Practical Materials Research Centre, National Academy of Sciences of Belarus,

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P. Brovki str., 19, Minsk, 220072 Belarus

Frank Laboratory of Neutron Physics, Joint Institute for Nuclear Research, Dubna, Moscow 5

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region, 141980 Russia

Donetsk Institute for Physics and Engineering, National Academy of Sciences of Ukraine, R. Luxembourg str., 72, Donetsk, 83114 Ukraine

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Donetsk Institute of Physics and Technology named after O.O. Galkin of the NAS of Ukraine, Nauky av., 46, Kyiv, 03680, Ukraine

Kiev National University named after Taras Shevchenko, Vladimirskaya str., 64/13, Kiev, 01601

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Ukraine

The BaFe12-xGaxO19 (x ≤ 1.2) hexaferrites were synthesized by the usual ceramic technology. It was been established that with the x increase the unit cell and magnetic parameters

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monotonically decrease. The frequency of natural ferromagnetic resonance firstly decreases from 49.6 GHz down to 49.1 GHz when x = 0.6 and then it increases up to 50.5 GHz. The line width

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monotonically increases from 3.5 GHz up to 5 GHz. The peak amplitude of resonant curve changes slightly with the exception for the x = 0.9 when it reaches -16 dB. The 1.3 GHz/kOe frequency shift in bias field is more intensive for small x = 0.3. The decreasing of the magnetic parameters is a result of the dilution of the Fe3+ - O2- - Fe3+ superexchange interactions. The behavior of the amplitude-frequency characteristics is largely determined by the reduction of the uniaxial exchange anisotropy. The prospects of the Ga-substituted hexaferrites as a material effectively absorbing the high-frequency electromagnetic radiation are shown. Key worlds: solid state reactions, crystal structure, magnetic and absorption measurements, doped hexaferrites. PACs: 81.40.Vw, 61.05.С-, 77.80.B1

1. INTRODUCTION

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The hexagonal hexaferrites of the M-type continue to attract the close attention of the researchers [1, 2]. The problems of electromagnetic interferences for the high-frequency electronic devices working in the gigahertz range have lately received increasing attention. Among various microwave absorbing materials the barium and strontium hexaferrites with hexagonal structure of M-type have been proved to be the most functional materials due to their simultaneous presence of dielectric and magnetic losses [3]. These compounds are characterized

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by coexistence of the strong intrasublattice Heisenberg exchange interactions and weak competing of the intersublattice exchange interactions. The intrasublattice interactions appear to dominate and form the ferrimagnetic structure with large magnetic parameters. The strong competing of the intersublattice exchange interactions can lead to non-collinear magnetic

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structures with small magnetic parameters such as a saturation magnetic moment and coercitivity [4].

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The interest to the BaFe12O19 barium hexaferrite of M-type with hexagonal structure and them solid solutions substituted by different diamagnetic cations (Al3+, In3+, Ga3+, Sc3+, etc.) [57] is explained also by their high functional properties [8]. The excellent chemical stability and corrosion resistance [9] do them ecologically safe and suitable for application practically without restrictions in time. The combination of high coercive force (Нс ~ 160 – 55 kA/m) with rather high residual induction allows to receive permanent magnets with satisfactory specific magnetic

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energy [10]. Their low conductivity (ρ ~ 108 Ω*cm) allows to apply hexaferrite magnets in the presence of high-frequency magnetic fields. For the first time, barium hexaferrite, isomorphic to PbO*6Fe2O3 magnetoplumbite, has been received in Philips firm [11] still in the 1950-th. The main magnetic, electric and structural properties of hexaferrites are discussed in the review [12].

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Until now the barium hexaferrite was widely used only as permanent magnets [13] and in magnetic storage of high density with perpendicular magnetization [14]. Recently the significant

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growth of publications on M-type barium hexaferrites caused by coexistence in them ferrimagnetic and ferroelectric ordering at the room temperature [15-20] is also noted. The Mtype barium hexaferrites are perspective for the absorption of the electromagnetic radiation (EMR) in the microwave range considering their magnetic properties and the possibilities of their modification by means of various substitutions including in the form of nanoparticles. There are works on effective absorption of EMR by this material in decimeter and centimetric spectral range [21] that provides electromagnetic compatibility of microelectronics and radio equipment devices. The high values of the magnetocrystalline anisotropy and the ferrimagnet-paramagnet phase transition temperature are main advantages of M-type barium hexaferrites. The collinear ferrimagnetic ordering with Curie temperature of ~ 740 K is formed in the M-type barium 2

hexaferrite. The change of magnetic bonds number of Fe3+ cations in multicomponent oxidic

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system caused by introduction in crystal structure of diamagnetic cations [22] or by creation of a deviation from a stoichiometry on oxygen [23] allows to operate its functional properties. The analysis of the M-type barium hexaferrite properties in the microwave range shows that the working range - the range of effective EMR absorption - lies in the centimetric spectral range [24]. The application of the substituted M-type barium hexaferrites with a large constant of the magnetocrystalline anisotropy as fillers of composite materials allows to carry out frequency

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selective absorption of EMR, using the controlled resonances of domain boundaries and rotation of magnetization (a natural ferromagnetic resonance, NFR). It is known that the absorption peak of the BaFe12O19 M-type barium hexaferrite lies in the range of ~ 47-50 GHz [25] whereas the substitution of iron cations with Mn2+ + Co2+ + Ti4+ cations reduces an absorption maximum

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down to 13.4 GHz [6]. It is considered that losses at high frequencies are generally caused by NFR. It is possible to displace the absorption peak and to expand an absorption strip in the

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microwave range by the controlling of the diamagnetic substitution level. Interesting to note that the promising high-efficiency and stable electromagnetic wave attenuation material such as the Bi0.8La0.2FeO3 bismuth orthoferrite has been reported [26]. With the increase of temperature, the attenuation capacity enhances, where the minimum reflection loss is less than -10 dB from 323 K to 673 K, and the best reflection loss reaches -54 dB at 573 K, which is 2.7 times that of BiFeO3. With changing frequency, the effective reflection loss

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(≤ -10 dB) almost covers 3 GHz in the full temperature range. The excellent attenuation capacity is attributed to the crystal and electron structures due to the substitution of La, which enhances conductivity and natural ferromagnetic resonance, resulting in the enhancement of

temperature.

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electromagnetic properties and improvement of electrical-magnetic synergy at elevated

The Nd doped BiFeO3 with electromagnetic matching, which exhibits tunable

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electromagnetic properties and high-performance microwave absorption has been reported. The experimental and calculated results demonstrate that Nd doping generates the ordered domain structure and changes the coupling states of electrons, which induce difficult polarization rotation and strong natural ferromagnetic resonance, leading to the decrease of dielectric loss and the increase of magnetic loss with increasing Nd concentration. The electromagnetic parameters are tuned from mismatching to matching, and the microwave absorption is improved. The Bi0.8Nd0.2FeO3 exhibits a remarkable reflection loss of -42 dB and bandwidth (≤ -10 dB) which covers nearly three quarters of the X-band at a thickness from 1.9 to 2.1 mm [27]. In this paper the absorption parameters for the weakly substituted barium hexaferrites are investigated. The results of this work can find application for ensuring intrasystem and intersystem electromagnetic compatibility and also for ensuring operational reliability of the 3

devices and the equipment in the conditions of the increased level of microwave influences due

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to selective absorption of EMR in the set range of frequencies. 2. EXPERIMENT TECHNIQUE The BaFe12-xGaxO19 (0 < x ≤ 1.2) polycrystalline samples were received from the Fe2O3 (99.999%), Ga2O3 (99.999%) oxides and the BaCO3 (chem. analysis purity) carbonate taken in the corresponding proportions [28] using ‘two-steps’ topotactic reactions (conventional solid reaction method). The particles size of the precursors was 0.5 - 2.5 µm. At first the oxides and

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carbonate were weighted to a prescribed ratio of cations and thoroughly mixed in an agate mortar. Then the chemical mixture was ground in a ball mill with a small amount of ethyl alcohol. The mixture was compressed into pellets with a diameter of 2 cm and a height of 1.5 cm by a hydraulic press in a steel press mold under a pressure of about 108 P. The 3 samples of each

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composition have been produced. The initial compositions were exposed to the synthesizing firing in air at 1200 0C (6 h). Then the pellets were ground again in a ball mill, pressed, and

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finally synthesized in air at 1300oC for 6 hs and slowly (100oC*h-1) cooled to room temperature. During the synthesis, the samples were kept on a platinum substrate. The temperature in a furnace with chromide lanthanum heaters was controlled by a platinum–platinum-rhodium (10%) thermocouple. The reference junction of the thermocouple was placed in melting ice. The heating and cooling rates of samples in the furnace were controlled by an RIF-101 device. The crystal structure of obtained samples was investigated by X-ray diffraction which is

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carried out on the powder D8 Advance diffractometer (Bruker) with the following parameters: 40 kV, 40 mА, Cu-Кα radiation (λ = 1.5406 Å). The refinement of X-ray diffraction data was carried out by the Ritveld full profile analysis [29] by means of the FullProf [30] program. In present paper the value of oxygen content and the temperature stability of oxygen

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sublattice were investigated by the thermogravimetric analysis (TGA) [31]. There is the lack of information about oxygen content for the ferrites, especially for the hexaferrites. It is generally

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accepted that for any interpretation of the properties of magnetic oxides the knowledge of oxygen stoichiometry is critical [32]. The TGA study was shown that the relative error of the oxygen content of the investigated hexaferrites is less than 0.6 % mol. Their oxygen content may be written as “ O18.9±0.1 ” for all the substitution concentrations [33]. The oxygen content remains stable up to 1000 °C. It was shown in many papers that magnetic behavior in oxygen deficient oxides changes dramatically with anionic deficiency [34]. The DC-susceptibility and specific magnetization were investigated by means of vibration sample magnetometer with universal cryogenic high-field measuring system (Liquid Helium Free High Field Measuring System by Cryogenic Ltd, London, UK) at a temperature of 300 K in external magnetic fields up to 2 T (field curves) and in the low field of 0.01 T in the temperature range of 4 – 750 K (temperature curves) [35]. The magnetic measurements were taken on 4

polycrystalline samples with average sizes of 2 х 3 х 5 mm3. The spontaneous magnetization was

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determined from field magnetization curve by linear extrapolation to the zero field [36]. The ferrimagnet-paramegnet phase transition temperature - the Curie temperature - was defined as an inflection point on temperature curve. This point is equivalent to a point of a minimum of derivative on temperature (min{dχ/dT}). In a point of derivative minimum the behavior of the temperature curve changes from "curved up" to "curved down" that corresponds to transition from fast decrease to slow [37].

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The measurements of the absorbing properties were performed in the range of 36 – 56 GHz. The sample was located in a metal wave guide with a cross-section of 5.2 x 2.6 mm2. The measurements were taken by means of the P2-68 chains scalar analyzer. The bias field was

are defined as :  ; 

и

P k ref = 10 * lg ref  Pinc

 ; 

(1)

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P k tr = 10 * lg tr  Pinc

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parallel to the electric field in a wave guide. The ktr transmission and kref reflection coefficients

where Pinc – the incident EMR power, Ptr – the transmission EMR power, Pref – the reflection EMR power. The ktr transmission and kref reflection coefficients are negative that indicates reduction of the transmitted and reflected EMR power in relation to the incident EMR power and they are measured by dB.

3. RESULTS AND DISCUSSIONS

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3.1. Crystal structure

The X-ray diffraction patterns for the BaFe12-xGaxO19 solid solutions with x = 0.1 and 1.2 at the room temperature are presented in Fig. 1. X-ray diffraction data correspond to the single-

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phase samples with a hexagonal unit cell of crystal structure and P63/mmc space group that agrees well with the previous results received earlier for the solid solutions with substitution by Al3+ and In3+ cations [38-40]. X-ray reflections have been indexed with help of the 00-043-0002

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ICDD card. The low values of fitting parameters such as the Rwp (3.21 – 5.42) weighted profile R-value, the Rexp (2.41 – 5.36) expected R-value, the RB (5.42 – 8.65) Bragg R-factor and the χ2 (1.52 – 2.03) goodness-of-fit quality factor suggest that the studied sample is of better quality and refinements of X-ray data are effective [41]. The (a and c) unit cell parameters are almost linear and they slightly decrease. In Fig. 2 the results of calculations of concentration dependences of the unit cell parameters and volume for all the BaFe12-xGaxO19 solid solutions are presented. The insignificant decrease of the unit cell parameters and, as a result, the unit cell volume is caused by the insignificant divergence of values of ionic radiuses of Ga3+ (0.62 Å) and Fe3+ (0.64 Å) cations [42]. This behavior of the unit cell parameters is consequence of the statistical distribution of the Ga3+ cations on different 5

nonequivalent crystallographic positions available for filling with Fe3+ cations. For the c

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parameter the slight deviation from Vegard's rule (Fig. 2a) is observed that it is due to likely removal of the initial strain of the unit cell with substitution. The initial strain occurs as a consequence of the rapid cooling of the ceramic after synthesis. The initial strain can be removed by the substitution as the ionic radius of Ga3+ cation is slightly smaller than the ionic radius of Fe3+ cation. Dash line indicates the fitting of the experimental points by the second order polynomial of the y(x) = A*x2 + B*x + C type.

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The model of magnetic structure of barium hexaferrite proposed by Gorter [43] assumes that the Fe3+ magnetoactive cations are located in 5 nonequivalent crystallographic positions which have octahedral (Fe1 – 2a, Fe4 – 4fVI and Fe5 – 12k), tetrahedral (Fe3 – 4fIV) and bipiramidal (Fe2 – 2b) oxygen surroundings. The substitution of the Fe3+ cations by the

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diamagnetic Ga3+ cations depending on preference of the positions taken by them can lead to some reduction of the values of the magnetic moments in the corresponding nonequivalent

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crystallographic positions. Furthermore the magnetic moments of these positions initially have the little different values because of the various oxygen coordinations [44]. The values of the main bond lengths and bond angles for the BaFe12-xGaxO19 solid solutions at room temperature are given in the Table. 1. As it is shown with the substitution level increase the 4 bond lengths such as the Fe2 – O3, Fe3 – O2, Fe4 – O5 and Fe5 – O1 decrease, while the remaining 5 bond lengths such as the Fe1 – O4, Fe2 – O1, Fe3 – O4, Fe4 – O3 and

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Fe5 – O2 increase. The 3 bond angles such as the Fe2 – O3 – Fe4, Fe5 – O2 – Fe5 and Fe5 – O4 – Fe5 decrease, while the other 3 bond angles such as the Fe3 – O4 – Fe5, Fe4 – O3 – Fe4 and Fe5 – O1 – Fe5 increase. The values of these bond lengths and bond angles helped to understand the change in the intensity of the exchange interactions and to interpret the change in

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electromagnetic properties with an increase in the substitution level. The samples had the density above > 98% with an average ~ 800 nm size of the crystallite.

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The individual crystallite had the shape of a regular planar hexagon (Fig. 3). The crystallites combine and form the entire ceramic. The crystallite size had certain dispersion. The crystallite size variation interval was 0.223 ÷ 1.279 µm for the BaFe11.9Ga0.1O19. For this sample 52.5 % of the crystallites had a size variation from 0.650 µm to 0.750 µm (Fig. 4a). For the BaFe10.8Ga1.2O19 sample the crystallite size variation interval was 0.218 ÷ 1.265 µm. For this sample 54.5 % of the crystallites had a size variation from 0.650 µm to 0.750 µm (Fig. 4b). The crystallites with size smaller than 0.170 µm and larger than 1.400 µm have been not detected. With the substitution level increase up to x = 1.2 the average crystallite size increases up to ~ 900 nm. The precise value of the average crystallite size for this sample from the quantitative

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stereologic analysis was 〈 D 〉 ≈ 0.773 µм MANUSCRIPT for the BaFe11.9Ga0.1O19 and 〈 D 〉 ≈ 0.895 µм for the ACCEPTED BaFe10.8Ga1.2O19 sample [45]. At the substitution the microstrains of the crystal lattice and the associated changes in the strain energy arise because of the differences in the ionic radii of iron and gallium. The information about microstrain was obtained from the diffraction line broadening. The dependences of the W2 reflection-half-width square versus d2 interplanar spacing square for the different substitution levels were constructed at room temperature. This dependence is the

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approximating function. The line broadening increased with the substitution level increase. The full width at half maximum of the diffraction line was described as in [40]. The true physical contribution in the line broadening was determined by FullProf program calculated as difference of widths between experimental samples and Al2O3 standard. In the ferrimagnetic crystals the

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separate sublattices give different contributions to general strain. Besides, the local environment symmetry of magnetic cations in ferrimagnetic crystals differs from macroscopic symmetry. This

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leads to the increase of the microscopic parameters number in comparison with the macroscopic one. The slope of the approximating function increases with the substitution level increase. This behavior indicates that the microstrain increases in crystallites.

The dependence of microstrain value versus the substitution level for the studied samples is shown in Fig. 5. The calculation of microstrains was performed for the isotropic approximation when the size effect is absent. The minimum microstrain is observed for the

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BaFe11.9Ga0.1O19 sample. The growth of the microstrain with the substitution level increase is associated with the increase of the system disorder, as a result of the statistical distribution of the gallium cations on the magnetic sublattices. This can make the different contributions to the total deformation. For the BaFe10.8Ga1.2O19 sample the maximum ~ 0.2 % microstrain is observed.

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3.2. Magnetic properties

For the BaFe12-xGaxO19 samples the ferrimagnet - paramagnet phase transition is usual

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second order phase transition according to temperature dependence of the susceptibility. At increase of the Ga3+ concentration the temperature of the phase transition smoothly decreases from 646 K for x = 0.1 to 577 K for x = 1.2 (Fig. 6) that is much lower than for the unsubstituted BaFe12O19 compound (TC = 740 K). This confirms that the substitution of the Fe3+ cations by the diamagnetic Ga3+ cations leads to the reduction of the number of magnetic neighbors of the iron cations, and, as a result, to earlier temperature destruction of the long-range magnetic order with heating. At the diamagnetic substitution the frustration of the magnetic subsystem occurs [46] as a result of the breakdowns of exchange coupled chains and the changes of the bond lengths and bond angles. This is due to the change of the bond lengths between the magnetoactive Fe3+ cations and O2- anions with the partial distortion of the valency bond angles that reduces the 7

exchange interaction energy. The detailed information about the bond lengths and bond angles

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between different nonequivalent crystallographic positions of the Fe3+ cations and O2- anions will be provided later in the next paper. From [47] It is well known that the I intensity of the indirect superexchange interactions for the complex 3d-element oxides depends on both the Mp+ - O2- - Mp+ bond angles and Mp+ – O2- bond lengths (p = 2, 3, 4, 5) through the overlap integrals between the 3d-orbitals of the Mp+ cation and the 2p-orbitals of the O2- anion. This I intensity is directly proportional to cosine of

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the bond angle I ~ cos(Mp+ - O2- - Mp+) and inversely proportional to bond length I ~ 1/(Mp+ - O2). This representation is true in ideal case of (Mp+ - O2- - Mp+)z (z = ∞) endless exchange coupled chains. In case of the breakdown or decrease of length of these endless exchange coupled chains the I intensity of the indirect superexchange interactions reduces and can change the sign. The

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decrease of the I intensity of the indirect superexchange interactions decreases the TC Curie temperature.

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The substitution of the Fe3+ cations by the Ga3+ cations leads to the 2 facts. Firstly the breakdowns and decreasing of length of (Fe3+(i) - O2- - Fe3+(j))z (i, j = 1, 2, 3, 4, 5; z = ∞) endless exchange coupled chains occur as a result of diamagnetic dilution. Secondly the changes of the Mp+ - O2- bond lengths and Mp+ - O2- - Mp+ bond angles occur as a result of differences in ionic radii of the Fe3+ and Ga3+ cations [48].

From these considerations and Table. 1 data it can be concluded that the main contribution

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to the weakening of the magnetic ordering with substitution level increase at room temperature occurs from the increase of the Fe1 - O4, Fe2 - O1, Fe2 - O3, Fe3 - O4, Fe4 - O3 and Fe5 - O2 bond lengths and the decrease of the Fe3 - O2, Fe4 - O5 and Fe5 - O1 bond lengths. At low temperatures the weakening of the magnetic ordering follows from the destruction of the

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intersublattice Fe3+(i) - O2- F e3+(j) (i ≠ j; i, j = 3, 4, 5) indirect superexchange interactions between Fe3, Fe4, Fe5 sublattices.

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In Fig. 6b the reciprocal magnetic susceptibility is presented. For all the samples only

positive values of the Θp paramagnetic Curie temperature are observed. This fact indicates the dominant character of the intrasublattice ferromagnetic exchange interactions. The Θp paramagnetic Curie temperature is exchange parameter which determines the intensity of exchange interactions. For the isotropic compounds with low uniaxial anisotropy the TC Curie temperature is almost equal to the Θp paramagnetic Curie temperature TC ~ Θp. The high temperature susceptibility for all the samples obeys the modified Curie-Weiss law χ = C/(T-Θp)γ. For the ferrimagnetic hexaferrite in the temperature range slightly above the TC (T > TC) the 1/χ(T) reciprocal value of the magnetic susceptibility (Fig. 6a) has hyperbolic form and only at the temperatures much higher than the TC (T >> TC) it obeys the Curie-Weiss law, i.e. it degenerates into a straight line. The hyperbolic temperature behavior of the reciprocal 8

susceptibility at T > TC for the hexaferrite is result of the effect of uniaxial exchange anisotropy.

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At the temperatures slightly above the TC in the hexaferrite the magnetic sublattices still exist. At the same time one of the sublattices is strong. Its magnetization is directed along the external B magnetic field. Others sublattices are weak. The magnetization of these sublattices is directed opposite to the external B magnetic field. As a result, in addition to the ferromagnetic paraprocess in the strong sublattice the antiferromagnetic paraprocess in the weak sublattices occurs. This antiferromagnetic paraprocess in the weak sublattices underestimates the value of

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the 1/χ(T) reciprocal susceptibility for the hexaferrite in the T > TC region (Fig. 6b).

The effective magnetic moment [49] of the Fe3+ cation has been experimentally detected. It has been determined according to the relation µ eff = (3kBC/n)1/2, where kB is the Boltzmann constant, n is the concentration of Fe3+ cations, C is the Curie constant, determined as C = 1/tgγ,

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where γ is the slope angle of 1/χ. For the BaFe11.9Ga0.1O19 the experimental value of the effective magnetic moment is ~ 4.11 µ B. For the BaFe10.8Ga1.2O19 the experimental value of the effective

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magnetic moment is ~ 4.35 µ B. However, the theoretical effective moment is determined as µ eff = g{S(S+1)}1/2µ B, where g is the gyromagnetic ratio ~ 2, S is the total spin of the Fe3+ cation 5/2, and µ B is the Bohr magneton. The theoretical effective moment is ~ 5.92 µ B per Fe3+ cation for the parent unsubstituted BaFe12O19.

The C Curie constant changes nonmonotonically with the substitution level. Firstly it increases up to x = 0.6 and then it drops. The µ eff ~ C1/2 effective magnetic moment in

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paramagnetic region (> 740 K) behaves similar to the Curie constant. It increases up to x = 0.6 and then it drops. This fact indicates the decrease of average magnetic moment per one Fe3+ magnetic cation with substitution as the trend. The positive (ferromagnetic) Fe3+ O2- Fe3+ superexchange interactions in particular magnetic sublattice are broken by introduction of the

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diamagnetic Ga3+ cations. The small increase of the effective magnetic moment is explained by partly location of Ga3+ cations in the different competing magnetic sublattices which is

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confirmed by the Rietveld fitting. The behavior of the specific magnetization for the BaFe12-xGaxO19 samples from field

dependence indicates the decrease of the maximum magnetic energy at the substitution level increase. From the Fig. 7a we can see that the largest χin(B) initial susceptibility is observed for the sample with x = 0.3. The smallest initial susceptibility is observed for the x = 0.1. The maximum value of the χdif(B) differential susceptibility decreases monotonically with the substitution level increase (Fig. 7b). The substitution by the Ga3+ cations leads to a weakening of the stiffness intrasublattice Fe3+ - O2- - Fe3+ superexchange interactions. This in turn leads to the increase of the initial magnetic susceptibility. However, the removal of the initial strain of the crystal structure with the substitution increase prevents the weakening of the stiffness of the superexchange interactions. Therefore the growth of the initial susceptibility is nonmonotonic. 9

The Bmax induction value of external magnetic field, at which the χmax = χ(Bmax) maximum value

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of the differential susceptibility is observed, decreases almost monotonically excluding the x = 0.6 sample. The shift of the χdif(B) differential susceptibility peaks toward low field with the x increase is due to a decrease in the uniaxial exchange anisotropy. We have summarized the main magnetic characteristics in Fig. 8. With the substitution level increase all the magnetic parameters decrease. The TC Cure temperature and Θp paramagnetic Curie temperature are close. The latter is some larger than former (Fig. 8a and 8b).

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This indicates that the strong positive Fe3+ O2- Fe3+ superexchange interactions still exist in different magnetic sublattices with the substitution growth. The µ permeability is determined by the χ susceptibility as µ = 1+4πχ. The Bmax induction value of external magnetic field at which the µ permeability reaches the µ max maximum value µ max = µ(Bmax) decreases from ~ 0.3 T down

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to ~ 0.05 T (Fig. 8c). The largest µ max maximum permeability equal of ~ 2850 in field of ~ 0.3 T is observed for the x = 0.1 sample (Fig. 8d). The smallest µ max maximum permeability equal of

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~ 1500 in field of ~ 0.05 T is observed for the x = 1.2 sample. It is noted the monotonic decrease in remanent magnetization and coercivity (Fig. 8e and 8f). The MS spontaneous magnetization monotonically decreases from ~ 56 emu/g for the x = 0.1 down to ~ 30 emu/g for the x = 1.2. The HC coercivity decreases from ~ 2.2 kOe for the x = 0.1 down to ~ 0.5 kOe for the x =1.2 The lack of the abrupt anomalies, i.e. the deviations from linear dependence of the magnetic energy decrease at the substitution level increase, on the temperature and field dependences of specific

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magnetization can indicate in favor of the version of the statistical distribution of Ga3+ cations between different nonequivalent crystallographic positions in structure of the M-type barium hexaferrite. Dash lines indicate the fitting of experimental points by second order polynomial of the y(x) = A*x2 + B*x + C type. Dot lines indicate the linear fitting.

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3.3. Electromagnetic properties In work [50] the expression determining the energy value of the electromagnetic radiation

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absorbed in material is received. The Eabs absorbed energy is proportional to the sum of the imaginary parts of ε// permittivity and µ// permeability as well as the frequency of the electromagnetic oscillations i.e. it is determined by the dielectric and magnetic losses. It is well known that the µ{ε} total comlex permeability is determined as µ{ε} = µ/{ε/} + ιµ//{ε//}. This implyies that at the interaction of the real materials with the electromagnetic field there are losses both due to the µ// magnetic losses and due to the ε// dielectric losses. The last include the conduction currents and the dielectric hysteresis phenomenon that takes into account by the permittivity. In the same work [50] it is shown that the absorption of the electromagnetic energy in the ferromagnetic materials is generally defined by the µ// magnetic losses as a result of the natural ferromagnetic resonance (NFR) [51] and the resonance of domain borders. 10

In Fig. 9 the EMR transmission spectra through the samples with different concentration of 3+

Ga

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cations including in different bias fields are presented. In the 46-50 GHz frequency range

the most intensively absorption of an electromagnetic wave caused by NFR phenomenon is observed. The abscissa value of the global minimum of the EMR transmission spectrum determines the fres resonant frequency of the transmission. The ordinate value of the global minimum of the EMR transmission spectrum determines the Ares resonant amplitude of the transmission. The global minimum width value measured at the Ares/2 half of the resonant

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amplitude determines the width of the Wres absorption band – band width. From Fig. 9 it is shown that all these three quantities are sensitive to the substitution level. The power of the transmission radiation decreases almost by 100 times.

The bias field also changes the amplitude-frequency characteristics of NFR. The samples

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with the low substitution level are more sensitive to the bias field. At the small values of the bias field a resonant frequency shift towards the major frequencies is observed as a consequence of

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the increase of the internal effective anisotropy field. At that the amplitude of the EMR transmission curve changes slightly. However at the biasing of the BaFe10.8Ga1.2O19 sample with the maximum substitution level the amplitude of the EMR transmission curve also increases together with the NFR frequency increase (see Fig. 9c). The increase of the Ares resonant amplitude occurs up to 1.5 kOe of the bias field, and then the amplitude begins to decrease that corresponds to behavior of imaginary part of the permeability for the hexaferrite at the

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ferromagnetic resonance.

From Fig. 10 it is shown that at the substitution level increase the value of the NFR frequency firstly decreases up to the x = 0.6 and then its value increases. At the x = 1.2 its value reaches

maximum

fres = 50.5 GHz

(Fig. 10a).

The Ares resonant

amplitude changes

EP

nonmonotonically. At the x = 0.6 the minimum value of the resonant amplitude Ares = -18.5 dB (Fig. 10b) is observed. The Wres absorption band increases monotonically with the substitution

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level increase and at the x = 1.2 it reaches maximum Wres = 5 GHz (Fig. 10c). The substitution of the Fe3+ cations by the Ga3+ cations up to the x = 0.6 leads to a

weakening of the stiffness of the intrasublattice Fe3+ - O2- - Fe3+ superexchange interactions. This decreases the fres resonant frequency and the Ares resonant amplitude. However, the removing of the initial strain of the crystal structure with substitution level increase up to the x = 1.2 prevents weakening of the stiffness of the superexchange interactions. And the fres resonant frequency and the Ares resonant amplitude decrease. The sharp increase of the Ares resonant amplitude for the x = 0.9 sample may be associated with a nonuniform distribution of Ga3+ cations over nonequivalent crystallographic positions. And as a result of this nonuniform distribution of Ga3+ cations the sharp decrease of the uniaxial exchange anisotropy is observed. Therefore the substitution level increase leads to nonmonotonic behavior of the amplitude-frequency 11

characteristics of the natural ferromagnetic resonance. The decrease of the uniaxial exchange

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anisotropy has no appreciable effect on the Wres absorption band and then it monotonically increases. Dash lines in Fig. 10 indicate the fitting of experimental points by the second order polynomial of the y(x) = Ax2 + Bx + C type. Dot lines indicate the linear fitting of all the experimental points. It is shown that all three amplitude-frequency characteristics fres(x), Ares(x) and Wres(x) increase with substitution level increase as trend. In Fig. 11 the frequency dependence of the reflection loss is presented in decibels for the

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BaFe10.8Ga1.2O19 sample including in different bias fields measured in the matched load mode. This dependence has difficult behavior for an explanation. It is possible to note that at the bias field increase the losses increase and at the field of the 5 kOe the minimum value kref = -33 dB is reached. The reflected EMR energy decreases by more than 3 orders. At the further increase of

SC

the bias field leads to decrease of the resonant curve intensity. At that the frequency of the resonant curve of reflection loss almost doesn't change.

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In Fig. 12 the dependence of the NFR frequency for the studied samples on the bias fields is presented. The increase of the resonant frequency at the bias field increase is observed since the internal anisotropy field increases. These dependences have almost linear behavior for all the samples. The resonant frequency is most sensitive to the bias field for the samples with the small Ga3+ cations concentration. While for almost all the samples the resonant frequency increases approximately on the 1.5 GHz at the bias field increase on the 1 kOe for the sample with the

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x = 0.1 the resonant frequency increases on the 2.2 GHz. At the search of the materials which are effectively working in the microwave range the region caused by NFR is of the greatest interest. The ferromagnetic resonance leads to the energy losses of the electromagnetic field which are result of a number of processes at the cations spin

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precession for the ferro- or ferrimagnets connected with the additional fluctuations of the crystal lattice sites [52]. The spin precession at the NFR occurs under the influence of the internal local

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magnetic fields as a result of the own magnetic anisotropy [53]. The M magnetization vector precesses around the easy direction so as if he is affected by a magnetic field - the anisotropy field. The physical principles responsible for the NFR losses are the same that at the induced ferromagnetic resonance. These are the additional fluctuations of the crystal lattice sites of the hexaferrite under the influence of spin waves. The interaction of spin waves with a crystal lattice leads to the fact that the part of the external alternating field energy exciting a thermal spin precession, and hence the spin waves, turns into the thermal fluctuations of the lattice. At that the NFR frequency is defined as the rotation stiffness of the magnetization vector in the plane of easy direction and the rotation stiffness out of this plane [54]. The receiving of the samples with the certain physical properties required for the effective absorption is usually reached by substitution of the Fe3+ cations by the diamagnetic and (or) 12

paramagnetic ions. At the substitution level increase of the hexaferrite by Sc3+, Ti4++Co2+ and 4+

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2+

Ti +Zn cations [55] it has been established the decrease of the saturation magnetization, Curie temperature and magnetocrystalline anisotropy that is connected with reduction of number of magnetic cations. The decrease of the resonant frequency is a consequence of the anisotropy field decrease. However, the substitution by the Al3+ cations along with the decrease of the saturation magnetization and Curie temperature leads to increase of the resonant frequency that is connected with increase of the magnetocrystalline anisotropy field [56]. The increase of the

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resonant frequency is also noted at the increase of the substitution level by the Cr3+ cations for the barium and strontium hexaferrites [57].

Ferrimagnetic resonance measurements were made at room temperature at frequencies range of 3 – 90 GHz for the Al3+, Ga3+ and Sc3+ substituted BaFe12O19 [58]. The anisotropy field

SC

from nearly zero up to 29 kOe was found for Sc-substitution levels x ≤ 1.65 and for Al levels x ≤ 2. The observed ∆W bandwidth can be described by a frequency independent two-magnon

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scattering contribution ranging between 5 Oe and 10 Oe, and an assumed intrinsic bandwidth rising linearly with frequency and being for the substitutions studied proportional to the reciprocal of the Curie temperature. When the thickness of the absorber coating from the BaFe12O19 hexaferrite prepared at relatively low 900 °C temperature was 2 mm, the minimum value of reflection loss reached -28.52 dB at about 13.80 GHz, and available bandwidth was approximately 9.3 GHz in the range of 8 – 18 GHz [21]. For the BaNixCo1-xTiFe10O19 powders

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synthesized via the sol-gel combustion method and mixed with the paraffin were found that the peaks of the complex permeability shifted to the high frequency region with the increase of the doped Ni. Moreover, the composite with x = 0.4 possessed a maximum reflection loss of 47.49 dB at 13.28 GHz with a matching thickness of 2.0 mm. It also had a bandwidth below -

EP

20 dB ranging from 12.36 GHz to 18 GHz [6]. For the BaMgxCo1-xTiFe10O19 synthesized by a simple sol-gel combustion technique was found a maximum reflection loss of -33.7 dB with a

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matching thickness of 2.0 mm measured in the frequency of 0.5 – 18 GHz, which also had a bandwidth below -20 dB ranging from 11.5 GHz to 17.2 GHz [59]. The analysis [60] of amplitude-frequency characteristics of absorption losses in the

substituted hexaferrites shows the opportunity to control the NFR frequency and the frequency shift by the x substitution level change. It is proposed [61] to approximate the resonant frequency change versus the Ti3++Co3+ cations concentration at x = 0-3.5 by the polynom of the second order in next form: f res (x ) = f res (0) + A * x 2 + B * x ,

(2)

where x – the substitution level, fres(x) and fres(0) – resonant frequency for the samples with the x and 0 substitution level, A =-1.9 and B =-4.2. 13

In our case the concentration dependence of the resonant frequency is nonmonotonic and it

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also characterized by a minimum at the x = 0.6. This dependence can be well approximated by the polynom of the second order in next form: f res (x ) = 50.04 + 3.37 * x 2 − 3.73 * x ,

(3)

It means that the resonant frequency firstly decreases with the substitution level increase up to the x ≈ 0.55, and then it increases. Such concentration behavior is observed at the monotonic decrease of the magnetic parameters such as the Curie temperature, spontaneous

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magnetization and coercive force with growth of the Ga3+ cations concentration [62].

With the substitution level increase the spontaneous magnetization decreases while the magnetocrystalline anisotropy field increases. At low (x ≤ 0.3) substitution the magnetization decrease leads to the increase of the initial susceptibility and permeability [63]. The

SC

magnetization decrease dominates the increase in the magnetocrystalline anisotropy. Thus the increase of the fres resonant frequency at x ≥ 0.6 is caused by increase of the magnetocrystalline

M AN U

anisotropy. The substitution up to x = 0.6 leads to a weakening of the stiffness of the intrasublattice Fe3+ - O2- - Fe3+ superexchange interactions. The fres resonant frequency and the Ares resonant amplitude decrease as a result of stiffness weakening of the exchange interactions. The main role in the Wres line broadening is played by static inhomogeneities such as the impurity cations. With the substitution increase the Wres line widths monotonically increases. As the samples have been received at the same time and on identical technology, they have identical

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morphology of crystallites. Therefore it is possible to assume that the contribution to EMR absorption of the domain borders resonance is not important value. It poorly depends on the substitution concentration [64].

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The kabs EMR absorption coefficient can be calculated from the experimentally received ktr transmission and kref reflection coefficients taking into account the energy conservation law on

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the formula:

(

)

k abs = 10 * lg 1 − 100.1*k tr − 100.1*k ref ,

(4)

All the coefficients are negative that indicates the reduction of EMR energy after

interaction with substance [65]. Moreover in practice it is necessary to obtain the great negative values of the ktr transmission and kref reflection coefficients to achieve the significant weakening of the transmitted and the reflected EMR energy [66]. At that the kabs EMR absorption coefficient will be small negative. In our case the absorption coefficient in a zero bias field is k 0abs = -0.09. In the bias field of 5 kOe the absorption coefficient increases up to the k 5abs = -0.05. It indicates that almost all the incident EMR energy is absorbed, and in the field of 5 kOe is observed the absorption maximum [67]. Such substances with large negative values of the ktr transmission and kref reflection coefficients and small negative values of the kabs absorption 14

coefficient have a big prospect for creation of a protective and antiradar covering of the air force

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objects according to the « Stealth » technology [68].

CONCLUSION The investigations of the crystal structure of the BaFe12-xGaxO19 (х = 0.1; 0.3; 0.6; 0.9 and 1.2) solid solutions of the ceramic samples are conducted by X-ray diffraction method in Cu-Kα radiation. All the studied compositions correspond to single-phase samples with hexagonal crystal structure and P63/mmc space group of symmetry. Isotropic and almost linear reduction of

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the unit cell parameters is caused by statistical distribution of diamagnetic substitution cations throughout all the ionic positions such as with the octahedral, tetrahedral and bipyramidal anion surroundings because of proximity of ionic radii of the Fe3+ (0.64 Å) and Ga3+ (0.62 Å). The ferrimagnet-paramagnet phase transition in the BaFe12-xGaxO19 samples is the second order one.

SC

The temperature of this phase transition at the increase of the Ga3+ cations concentration smoothly decreases from 646 K (for x = 0.1) to 577 K (for x = 1.2) that is caused by decreasing

M AN U

of the bonds number of the magnetoactive iron cations with the oxygen anions. The magnetization behavior of the samples indicates on decrease of energy of the Fe3+ - O2- - Fe3+ exchange interactions at increase of the Ga3+ cations concentration. The lack of anomalies on the temperature and field dependences of specific magnetization evidences in favor of statistical distribution of the Ga3+ cations throughout all the sublattices in structure. The realized researches of the absorbing properties have shown noticeable influence of the diamagnetic substitution on

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the microwave characteristics of the studied samples. With the substitution level increase the NFR frequency firstly decreases from 49.6 GHz down to 49.2 GHz at the x = 0.6 and then the NFR frequency increases up to 50.6 GHz at the x = 1.2. At that the intensity of resonant curves changes slightly. The application of the bias field considerably shifts the resonant frequency of

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the samples at the small Ga3+ cations concentration towards the major frequencies. The substitution of the Fe3+ cations by the Ga3+ cations increases the frequency range where the

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intensive absorption of electromagnetic energy is observed that is required for the protective and antiradar shielding from the microwave radiation.

ACKNOWLEDGMENT

Present work is realized at joint financing of the Ministry of Education and Science of the Russian Federation on the program of Increase of Competitiveness of NUST "MISIS" among the leading world scientific and educational centers (No. K4-2015-040, No. K3-2016-019, No. К32017-028, No. К4-2017-041), with support and within the state order of the Russian Federation Government on the organization of scientific work, and with assistance of grants of BRFBR (No. F17D-003). In SUSU this work was supported by the Ministry of Education and Science of the Russian Federation (4.1346.2017/4.6) by Act 211 of the Government of the Russian Federation (contract No. 02.A03.21.0011). L. Panina acknowledges support under the Russian Federation State contract for organizing a scientific work. 15

REFERENCES ACCEPTED MANUSCRIPT 1.

E.H. Na, S. Song, Y.-M. Koo, H.M. Jang, Relaxor-like improper ferroelectricity induced by Si*Sj-type collinear spin ordering in a M-type hexaferrite PbFe6Ga6O19, Acta Mater. 61 (2013) 7705-7711.

2.

J. Singh, C. Singh, D. Kaur, S.B. Narang, R. Joshi, S.R. Mishra, R. Jotania, M. Ghimire, C.C. Chauhan, Tunable microwave absorption in Co-Al substituted M-type Ba-Sr hexagonal ferrite, Mater. Des. 110 (2016) 749-761. Z. Durmus, A. Durmus, H. Kavas, Synthesis and characterization of structural and

RI PT

3.

magnetic properties of graphene/hard ferrite nanocomposites as microwave-absorbing material, J. Mater. Sci. 50 (2015) 1201-1213. 4.

T.A. Kaplan, N. Menyuk, Spin ordering in three-dimensional crystals with strong

5.

SC

competing exchange interactions, Phil. Mag. 87 (2007) 3711-3785.

L. Wang, H. Yu, X. Ren, G. Xu, Magnetic and microwave absorption properties of

6.

M AN U

BaMnxCo1−xTiFe10O19, J. Alloys Compd. 588 (2014) 212-216.

P. Meng, K. Xiong, L. Wang, S. Li, Y. Cheng, G. Xu, Tunable complex permeability and enhanced microwave absorption properties of BaNixCo1−xTiFe10O19, J. Alloys Compd. 628 (2015) 75-80.

7.

Y. Li, M. Cao, Enhanced electromagnetic properties and microwave attenuation of BiFeO3BaFe7(MnTi)2.5O19 driven by multi-relaxation and strong ferromagnetic resonance, Mater.

8.

TE D

Des. 110 (2016) 99-104.

G.-L. Tan, H.-H. Sheng, Multiferroism and colossal magneto-capacitance effect of La0.2Pb0.7Fe12O19 ceramics, Acta Mater. 121 (2016) 144-151.

9.

X. Liu, J. Wang, L.M. Gan, S.C. Ng, J. Ding, An ultrafine barium ferrite powder of high

10.

EP

coercivity from water-in-oil microemulsion, J. Magn. Magn. Mater. 184 (1998) 344-354. D.A. Vinnik, D.A. Zherebtsov, L.S. Mashkovtseva, S. Nemrava, M. Bischoff, N.S. Perov,

AC C

A.S. Semisalova, I.V. Krivtsov, L.I. Isaenko, G.G. Mikhailov, R. Niewa, Growth, structural and magnetic characterization of Al-substituted barium hexaferrite single crystals, J. Alloys Compd. 615 (2014)1043-1046.

11.

J.J. Went, G.W. Rathenau, E.W. Gorter, G.W. van Oosterhout, Hexagonal iron-oxide compounds as permanent-magnet materials, Phys. Rev. 86 (1952) 424-425.

12.

R.C. Pullar, Hexagonal ferrites: a review of the synthesis, properties and applications of hexaferrite ceramics, Prog. Mater. Sci. 57 (2012) 1191-1334.

13.

E. Richter, T.J.E. Miller, T.W. Neumann, T.L. Hudson, The ferrite PMAC motor-A technical and economic assessment, IEEE Trans. Industry Applications 1A-21 (1985) 644650. 16

14.

Q.A. Pankhurst, R.S. Pollard, Fine-particle magnetic oxides, J. Phys.: Condens. Mater. 5

ACCEPTED MANUSCRIPT

(1993) 8487-8508. 15.

Y. Tokunaga, Y. Kaneko, D. Okuyama, S. Ishiwata, T. Arima, S. Wakimoto, K. Kakurai, Y. Taguchi, Y. Tokura, Multiferroic M-type hexaferrites with a room-temperature conical state and magnetically controllable spin helicity, Phys. Rev. Lett. 105 (2010) 257201-4.

16.

G. Tan , X. Chen, Structure and multiferroic properties of barium hexaferrite ceramics, J. Magn. Magn. Mater. 327 (2013) 87-90. A.V. Trukhanov,

V.O. Turchenko,

I.A. Bobrikov,

S.V. Trukhanov,

I.S. Kazakevich,

RI PT

17.

A.M. Balagurov, Crystal structure and magnetic properties of the BaFe12−xAlxO19 (x = 0.1– 1.2) solid solutions, J. Magn. Magn. Mater. 393 (2015) 253-259. 18.

V.G. Kostishyn, L.V. Panina, L.V. Kozhitov, A.V. Timofeev, A.N. Kovalev, Synthesis and

SC

multiferroic properties of M-type SrFe12O19 hexaferrite ceramics, J. Alloy Compd. 645 (2015) 297-300. S.V. Trukhanov,

A.V. Trukhanov,

V.G. Kostishin,

L.V. Panina,

I.S. Kazakevich,

M AN U

19.

V.A. Turchenko, V.V. Kochervinskiy, Coexistence of spontaneous polarization and magnetization in substituted M-type hexaferrites BaFe12–xAlxO19 (x ≤ 1.2) at room temperature, JETP Lett. 103 (2016) 100-105. 20.

V.G. Kostishyn, L.V. Panina, А.V. Timofeev, L.V. Kozhitov, A.N. Kovalev, A.K. Zyuzin, Dual ferroic properties of hexagonal ferrite ceramics BaFe12O19 and SrFe12O19, J. Magn.

21.

TE D

Magn. Mater. 400 (2016) 327-332.

L. Li, K. Chen, H. Liu, G. Tong, H. Qian, B. Hao, Attractive microwave-absorbing properties of M-BaFe12O19 ferrite, J. Alloys Compd. 557 (2013) 11-17.

22.

V.A. Turchenko, A.V. Trukhanov, S.V. Trukhanov, I.A. Bobrikov, A.M. Balagurov,

EP

Features of crystal and magnetic structures of solid solutions BaFe12-xDxO19 (D = Al3+, In3+; x = 0.1) in a wide temperature range, Eur. Phys. J. Plus 131 (2016) 82-10. S.V. Trukhanov, A.V. Trukhanov, A.N. Vasiliev, H. Szymczak, Frustrated exchange

AC C

23.

interactions formation at low temperatures and high hydrostatic pressures in La0.70Sr0.30MnO2.85, JETP 111 (2010) 209-214.

24.

N. Velhal, G. Kulkarni, D. Mahadik, P. Chowdhury, H. Barshilia, V. Puri, Effect of Ba+2

ion on structural, magnetic and microwave properties of screen printed BaxSr1-XFe12O19 thick films, J. Alloys Compd. 682 (2016) 730-737.

25.

M. Labeyrie, J.C. Mage, W. Simonet, J.M. Desvignes, H. Le Gall, FMR linewidth of barium hexaferrite at millemeter wavelengths, IEEE. Trans. Magn. Mag-20 (1984) 12241226.

17

26.

Y. Li,

M.-Sh. Cao,

D.-W. Wang, J. Yuan, High-efficiency and dynamic stable ACCEPTED MANUSCRIPT

electromagnetic wave attenuation for La doped bismuth ferrite at elevated temperature and gigahertz frequency, RSC Adv. 5 (2015) 77184–77191. 27.

Y. Li, W.-Q. Cao, J. Yuan, D.-W. Wang, M.-Sh. Cao, Nd doping of bismuth ferrite to tune electromagnetic properties and increase microwave absorption by magnetic–dielectric synergy, J. Mater. Chem. C 3 (2015) 9276-9282.

28.

A.V. Trukhanov, L.V. Panina, S.V. Trukhanov, V.A. Turchenko, M. Salem, Evolution of

RI PT

structure and physical properties in Al-substituted Ba-hexaferrites, Chin. Phys. B 25 (2016) 016102-6. 29.

H.M. Rietveld, A profile refinement method for nuclear and magnetic structures, J. Appl. Cryst. 2 (1969) 65-71. http://www.ill.eu/sites/fullprof/.

31.

S.V. Trukhanov, A.V. Trukhanov, S.G. Stepin, H. Szymczak, C.E. Botez, Effect of the size

SC

30.

M AN U

factor on the magnetic properties of manganite La0.50Ba0.50MnO3, Phys. Sol. State 50 (2008) 886-893. 32.

A.V. Trukhanov,

S.V. Trukhanov,

An.V. Trukhanov,

E.L. Trukhanova,

L.V. Panina,

V.G. Kostishyn,

V.O. Natarov,

I.S. Kazakevich,

V.A. Turchenko,

M.M. Salem,

A.M. Balagurov, Evolution of structure and magnetic properties for BaFe11.9Al0.1O19 hexaferrite in a wide temperature range, J. Magn. Magn. Mater. 426 (2017) 487-496. S.V. Trukhanov, A.V. Trukhanov, C.E. Botez, A.H. Adair, H. Szymczak, R. Szymczak,

TE D

33.

Phase separation and size effects in Pr0.70Ba0.30MnO3+δ perovskite manganites, J. Phys.: Condens. Matter 19 (2007) 266214-18. 34.

S.V. Trukhanov,

A.V. Trukhanov,

V.G. Kostishyn,

L.V. Panina,

V.A. Turchenko,

EP

I.S. Kazakevich, An.V. Trukhanov, E.L. Trukhanova, V.O. Natarov, A.M. Balagurov, Thermal evolution of exchange interactions in lightly doped barium hexaferrites, J. Magn.

35.

AC C

Magn. Mater. 426 (2017) 554-562. S.V. Trukhanov, A.V. Trukhanov, A.N. Vasiliev, A.M. Balagurov, H. Szymczak, Magnetic state of the structural separated anion-deficient La0.70Sr0.30MnO2.85 manganite, JETP 113

(2011) 819-825.

36.

V.D. Doroshev,

V.A. Borodin,

V.I. Kamenev,

A.S. Mazur,

T.N. Tarasenko,

A.I. Tovstolytkin, S.V. Trukhanov, Self-doped lanthanum manganites as a phase-separated system: Transformation of magnetic, resonance, and transport properties with doping and hydrostatic compression, J. Appl. Phys. 104 (2008) 093909-13. 37.

S.V. Trukhanov, A.V. Trukhanov, A.N. Vasil’ev, A. Maignan, H. Szymczak, Critical behavior of La0.825Sr0.175MnO2.912 anion-deficient manganite in the magnetic phase transition region, JETP Lett. 85 (2007) 507-512. 18

38.

V.A. Turchenko, A.V. Trukhanov, I.A. Bobrikov, S.V. Trukhanov, A.M. Balagurov,

ACCEPTED MANUSCRIPT

Investigation of the crystal and magnetic structures of BaFe12-xAlxO19 solid solutions (x = 0.1-1.2), Crystallogr. Rep. 60 (2015) 629-635. 39.

S.V. Trukhanov,

A.V. Trukhanov,

V.O. Turchenko,

V.G. Kostishin,

L.V. Panina,

I.S. Kazakevich, A.M. Balagurov, Crystal structure and magnetic properties of the BaFe12−xInxO19 (x=0.1–1.2) solid solutions, J. Magn. Magn. Mater. 417 (2016) 130-136. 40.

S.V. Trukhanov,

A.V. Trukhanov,

V.A. Turchenko,

V.G. Kostishyn,

L.V. Panina,

RI PT

I.S. Kazakevich, A.M. Balagurov, Structure and magnetic properties of BaFe11.9In0.1O19 hexaferrite in a wide temperature range, J. Alloy Compd. 689 (2016) 383-393. 41.

D.A. Vinnik, A.B. Ustinov, D.A. Zherebtsov, V.V. Vitko, S.A. Gudkova, I. Zakharchuk, E. Lähderanta, R. Niewa, Structural and millimeter-wave characterization of flux grown Al

42.

SC

substituted barium hexaferrite single crystals, Ceram. Int. 41 (2015) 12728-12733. R.D. Shannon, Revised effective ionic radii and systematic studies of interatomic distances

43.

M AN U

in halides and chalcogenides, Acta Crystallogr. A 32 (1976) 751-767. E.W. Gorter, Some properties of ferrites in connection with their chemistry, Proc. IRE 43 (1955) 1945-1973. 44.

S.V. Trukhanov, Magnetic and magnetotransport properties of La1−xBaxMnO3−x/2 perovskite manganites, J. Mater. Chem. 13 (2003) 347-352.

45.

S.V. Trukhanov,

A.V. Trukhanov,

V.G. Kostishyn,

L.V. Panina,

An.V. Trukhanov,

TE D

V.A. Turchenko, D.I. Tishkevich, E.L. Trukhanova, O.S. Yakovenko, L.Yu. Matzui, Investigation into the structural features and microwave absorption of doped barium hexaferrites, Dalton Trans. In press (2017). 46.

V.V. Atuchin, D.A. Vinnik, T.A. Gavrilova,

S.A. Gudkova,

L.I. Isaenko, X. Jiang,

EP

L.D. Pokrovsky, I.P. Prosvirin, L.S. Mashkovtseva, Z. Lin, Flux crystal growth and the electronic structure of BaFe12O19 hexaferrite, J. Phys. Chem. C 120 (2016) 5114-5123. P.G. Radaelli, G. Iannone, M. Marezio, H.Y. Hwang, S.-W. Cheong, J.D. Jorgensen,

AC C

47.

D.N. Argyriou, Structural effects on the magnetic and transport properties of perovskite A1−xA′xMnO3 (x=0.25, 0.30), Phys. Rev. B 56 (1997) 8265-8276.

48.

S.V. Trukhanov,

A.V. Trukhanov,

V.G. Kostishyn,

L.V. Panina,

V.A. Turchenko, D.I. Tishkevich, E.L. Trukhanova, V.V. Oleynik,

An.V. Trukhanov, E.S. Yakovenko,

L.Yu. Matzui, D.A. Vinnik, Magnetic, dielectric and microwave properties of the BaFe12xGaxO19

(x ≤ 1.2) solid solutions at room temperature, J. Magn. Magn. Mater. In press

(2017). 49.

A. Sundaresan, A. Maignan, B. Raveau, Effect of A-site cation size mismatch on charge ordering and colossal magnetoresistance properties of perovskite manganites, Phys. Rev. B 56 (1997) 5092-5095. 19

50.

L.D. Landau, L.P. Pitaevskii, E.M. Lifshitz, Electrodynamics of Continuous Media, Second

ACCEPTED MANUSCRIPT

Edition, Butterworth-Heinemann, (1984) p. 253. 51.

A.J.E. Welch, P.F. Nicks, A. Fairweather, F.F. Roberts, Natural ferromagnetic resonance, Phys. Rev. 77 (1950) 403-403.

52.

L. Ne’el, Magnetic properties of ferrites: ferrimagnetism and antiferromagnetism, Annales de Physique 3 (1948) 137-198.

53.

A.V. Trukhanov,

S.V. Trukhanov,

L.V. Panina,

V.G. Kostishyn,

D.N. Chitanov,

RI PT

I.S. Kazakevich, An.V. Trukhanov, V.A. Turchenko, M. Salem, Strong corelation between magnetic and electrical subsystems in diamagnetically substituted hexaferrites ceramics, Ceram. Int. 43 (2017) 5635-5641. 54.

C. Kittel, On the theory of ferromagnetic resonance absorption, Phys. Rev. 73 (1948) 155-

55.

SC

161.

J. Smith, H.P.J. Wijn, Ferrites, John Willey and Sons, New York, Eindhoven, (1959)

56.

L.G. Van Uitert, Low magnetic saturation ferrites for microwave applications, J. Appl. Phys. 26 (1955) 1289-1290.

57.

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p. 321.

M.El. Rayess, J.B. Sokoloff, C. Vittoria, W. Spurgeon, Frequency dependence of the ferromagnetic resonance linewidth of barium ferrite, J. Appl. Phys. 67 (1990) 5527-5529.

58.

P. Röschmann, M. Lemke, W. Tolksdorf, F. Welz, Anisotropy fields and FMR linewidth in

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single crystal Al, Ga and Sc substituted hexagonal ferrites with M structure, Mat. Res. Bull. 19 (1984) 385-392. 59.

J. Chen, P. Meng, M. Wang, G. Zhou, X. Wang, G. Xu, Electromagnetic and microwave absorption properties of BaMgxCo1−xTiFe10O19, J. Alloys Compd. 679 (2016) 335-340. R.S. Alam, M. Moradi, M. Rostami, H. Nikmanesh, R. Moayedi, Y. Bai, Structural,

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60.

magnetic and microwave absorption properties of doped Ba-hexaferrite nanoparticles

61.

AC C

synthesized by co-precipitation method, J. Magn. Magn. Mater. 381 (2015) 1-9. L.L. Eremtsova,

I. Nedkov,

V.P. Cheparin,

A.A. Kitaytsev,

Natural

ferromagnetic

resonance in doped hexaferrites, Inorg. Mater. 8 (1972) 59-65.

62.

I. Bsoul, S.H. Mahmood, Magnetic and structural properties of BaFe12−xGaxO19

nanoparticles, J. Alloys Compd. 489 (2010) 110-114.

63.

I.O. Troyanchuk, S.V. Trukhanov, D.D. Khalyavin, H. Szymczak, Magnetic properties of anion deficit manganites Ln0.55Ba0.45MnO3-γ (Ln = La, Nd, Sm, Gd, γ ≤ 0.37), J. Magn. Magn. Mater. 208 (2000) 217-220.

64.

R.N. Summergrad. E. Banks, New hexagonal ferrimagnetic oxides, J. Phys. Chem. Sol. 2 (1957) 312-317. 20

65.

I.O. Troyanchuk,

S.V. Trukhanov,

H. Szymczak, J. Przewoznik, K. Bärner, Phase ACCEPTED MANUSCRIPT

transitions in La1-xCaxMnO3-x/2 manganites, JETP 93 (2001) 161-167. 66.

A.H. Mones, E. Banks, Cation substitutions in BaFe12O19, J. Phys. Chem. Sol. 4 (1958) 217-222.

67.

S.V. Trukhanov, A.V. Trukhanov, H. Szymczak, C.E. Botez, A. Adair, Magnetotransport properties and mechanism of the A-site ordering in the Nd-Ba optimal-doped manganites, J. Low Temp. Phys. 149 (2007) 185-199.

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vehicles, Prog. Aerosp. Sci. 43 (2007) 218-245.

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S.P. Mahulikar, H.R. Sonawane, G.A. Rao, Infrared signature studies of aerospace

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68.

21

FIGURE CAPTIONS ACCEPTED MANUSCRIPT

Fig. 1. Powder X-ray diffraction I(2θ) patterns at T = 300 K for the BaFe11.9Ga0.1O19 (a-panel) and BaFe10.8Ga1.2O19 (b-panel) solid solutions. Crosse denotes the experimental data. Solid line is theoretical model. Low solid line is difference curve between the experimental and theoretical data. Vertical bar is permissible position of Bragg reflection.

Fig. 2. Concentration dependences of the а(x) (full rectangles) (a-panel) and с(x) (full circles) (b-

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panel) unit cell parameters and V(x) (full up-triangles) (c-panel) unit cell volume at the T = 300 K for the BaFe12-xGaxO19 (х = 0.1; 0.3; 0.6; 0.9 and 1.2) solid solutions. Solid lines are linear interpolation of all the data. Dash lines are linear interpolation of two limit points. Dot line is second order polynomial interpolation of all the data.

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Fig. 3. Typical surface topography photos obtained with the help of a scanning electron microscope at 300 K for the BaFe11.9Ga0.1O19 (a-panel) and BaFe10.8Ga1.2O19 (b-panel)

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solid solutions.

Fig. 4. Distribution F(d) diagrams of crystallites by size at 300 K for the BaFe11.9Ga0.1O19 (apanel) and BaFe10.8Ga1.2O19 (b-panel) solid solutions. Solid lines indicate the fitting of experimental data by Lorentz model.

Fig. 5. Concentration ε(x) dependence of microstrain for the BaFe12-xGaxO19 solid solutions at 300 K.

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Fig. 6. Temperature dependences of the χ-1(T) reciprocal susceptibility (a-panel) and the dχ*(dT)-1 (T) temperature susceptibility derivative (b-panel) for the BaFe12-xGaxO19 solid solutions with х = 0.1 (full rectangles); 0.3 (open rectangles); 0.6 (full circles); 0.9 (open circles) and 1.2 (full up-triangles). Dash lines are linear interpolation of the high

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temperature part of susceptibility.

Fig. 7. Field dependences of the χin(B) initial susceptibility (a-panel) and χdif(B) differential

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susceptibility (b-panel) in low fields at the T = 300 K for the BaFe12-xGaxO19 solid

solutions with х = 0.1 (full rectangles); 0.3 (open rectangles); 0.6 (full circles); 0.9 (open circles) and 1.2 (full up-triangles).

Fig. 8. Concentration dependences of the TC(x) Curie temperature (a-panel), the Θp(x) paramagnetic Curie temperature (b-panel), the Bmax(x) DC external magnetic field induction (c-panel) at which the equality is performed µ max = µ(Bmax), the µ max(x) maximum value of permeability (d-panel), the MS(x) spontaneous specific magnetization (e-panel) and the HC(x) coercive force (f-panel) at the T = 300 K for the BaFe12-xGaxO19 (х = 0.1; 0.3; 0.6; 0.9 and 1.2) solid solutions. Dash lines indicate the fitting of experimental values by second order polynomial. Dot lines indicate the linear fitting. 22

Fig. 9. Frequency dependences of the ktr(f) transmission coefficient (transmission loss) in zero

ACCEPTED MANUSCRIPT

H = 0 kOe external magnetic bias field for the BaFe12-xGaxO19 solid solutions with х = 0.1 (full rectangles), 0.9 (open rectangles) and 1.2 (full circles) (a-panel), in H = 0.7 kOe (full rectangles), 2 kOe (open rectangles) and 2.5 kOe (full circles) external magnetic bias fields for the BaFe12-xGaxO19 solid solution wit х = 0.1 (b-panel) and in H = 0.7 kOe (full rectangles), 1.5 kOe (open rectangles) and 3.5 kOe (full circles) external magnetic bias fields for the BaFe12-xGaxO19 solid solution with х = 1.2 (c-panel) at the T = 300 K.

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Fig. 10. Concentration dependences of the amplitude-frequency characteristic of the EMR transmission process : the fres(x) NFR frequency (a-panel), the Ares(x) = k max (x) NFR tr amplitude (b-panel) and the Wres(x) NFR band width (c-panel) at the T = 300 K in zero H = 0 kOe external magnetic bias field for the BaFe12-xGaxO19 (х = 0.1; 0.3; 0.6; 0.9 and

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1.2) solid solutions. Dash lines indicate the fitting of experimental values by second order polynomial. Dot lines indicate the linear fitting.

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Fig. 11. Frequency dependences of the kref(x) reflection coefficient (reflection loss) at the T = 300 K in H = 0 kOe (full rectangles), 2 kOe (open rectangles) and 5 kOe (full circles) external magnetic bias fields for the BaFe12-xGaxO19 solid solution with х = 1.2.

Fig. 12. External magnetic bias field dependences of the fres(H) NFR frequency at the T = 300 K for the BaFe12-xGaxO19 solid solutions with х = 0 (full asterisks), 0.1 (full rectangles), 0.3

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(open rectangles), 0.6 (full circles), 0.9 (open circles) and 1.2 (full up-triangles).

23

Table. 1. Values of the main bond lengths and bond angles for the BaFe12-xGaxO19 (х = 0.1; 0.3;

ACCEPTED MANUSCRIPT

0.6; 0.9 and 1.2) solid solutions at 300 K.

x = 0.1

x = 0.3

x = 0.6

x = 0.9

x = 1.2

Fe1 – O4, Å

1.983

1.991

2.013

2.027

2.048

Fe2 – O1, Å

2.314

2.176

2.282

2.351

2.445

Fe2 – O3, Å

1.807

1.817

1.845

1.862

1.835

Fe3 – O2, Å

1.975

1.946

1.887

1.843

1.790

Fe3 – O4, Å

1.915

1.915

1.920

1.920

1.925

Fe4 – O3, Å

2.134

2.151

2.192

2.216

2.253

Fe4 – O5, Å

1.984

1.976

1.966

1.955

1.945

Fe5 – O1, Å

1.975

1.967

1.958

1.947

1.938

Fe5 – O2, Å

2.063

2.075

2.107

2.124

2.153

Fe2 – O3 – Fe4, deg

138.67

138.08

136.92

136.11

135.05

Fe3 – O4 – Fe5, deg

120.67

121.13

122.19

122.80

123.76

Fe4 – O3 – Fe4, deg

82.87

83.93

86.25

87.88

90.06

Fe5 – O1 – Fe5, deg

98.66

98.83

99.24

99.47

99.85

Fe5 – O2 – Fe5, deg

89.75

89.37

88.60

88.04

87.34

Fe5 – O4 – Fe5, deg

88.74

83.46

72.82

65.79

56.31

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Bond length/angle

24

4

20

40

2Θ ( deg )

Fig. 1

25

60 (1 1 16)

(2 0 14)

(2 0 13)

(2 1 7) (2 0 11)

40

2Θ ( deg )

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0

(2 0 9)

(1 0 5) (2 0 6)

12 (1 1 4)

20

(2 0 3)

b (1 0 7)

(2 1 7)

(1 0 5)

(2 0 3)

(1 1 16)

(2 0 13)

RI PT (2 0 14)

(2 0 9)

(1 0 11)

(2 0 6)

(1 0 8)

(1 1 0)

(1 1 2)

(2 0 11)

(0 0 6)

(1 1 4)

12

(1 0 8)

(1 1 2)

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8

(1 1 0)

(1 0 1)

4 (1 0 2)

8

(0 0 6)

EP (1 0 1) (1 0 2)

I ( arb. un. )

(1 0 7)

a

(1 0 11)

AC C I ( arb. un. )

ACCEPTED MANUSCRIPT

BaFe11.9Ga0.1O19 300K

60 80

BaFe10.8Ga1.2O19 300K

0

80

ACCEPTED MANUSCRIPT a

a(A)

5,892

5,888

5,884

300K

0,4

x

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AC C 3

0,4

x

0,8

1,2 c

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0,0

V(A )

b

BaFe12-xGaxO19 300K

697

1,2

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c(A)

23,19

23,18

0,8

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0,0

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BaFe12-xGaxO19

696

BaFe12-xGaxO19

695

0,0

300K

0,4

x

Fig. 2

26

0,8

1,2

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a

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ACCEPTED MANUSCRIPT

b

Fig. 3

27

ACCEPTED MANUSCRIPT Lorentz

Equation

y = y0 + (2*A/ PI)*(w/(4*(x-xc )^2 + w^2))

Reduced ChiSqr

1,03435

Adj. R-Square

0,99524

a

BaFe11.9Ga0.1O19 Standard Error

y0

-0,90534

0,40597

B

xc

0,69338

0,00296

B

w

0,13773

0,00541

B B

A H

11,67511 53,96649

0,46216

T=300K

20

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F(%)

Value B

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40

Model

0,0

0,2

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0 0,4

0,6

0,8

1,0

1,2

1,4

d ( µm )

60 Lorentz

Equation

y = y0 + (2*A/ PI)*(w/(4*(x-xc )^2 + w^2))

Reduced ChiSqr

0,70349

Adj. R-Square

0,99694

Value

B

B

20

-0,77163

0,33015

xc w

0,69446 0,12972

0,00248 0,0042

A

11,35303

0,37427

H

55,71527

T=300K

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B

Standard Erro

y0

AC C

F(%)

B B

b

BaFe10.8Ga1.2O19

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40

Model

0

0,0

0,2

0,4

0,6

0,8

d ( µm )

Fig. 4

28

1,0

1,2

1,4

ACCEPTED MANUSCRIPT

0,20

BaFe12-xGaxO19

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T=300K

ε(%)

0,18

0,0

0,2

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0,16

0,4

0,6

0,8

Fig. 5

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x

29

1,0

1,2

ACCEPTED MANUSCRIPT 6 x=0.9

x=1.2

x=0.6

4

x=0.3

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x=0.1 2

BaFe12-xGaxO19

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-1

χ ( arb. un. )

a

0

700

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600

800

T(K)

b 0,0

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-0,2

AC C

-0,4

EP

x=0.6

-1

-1

dχ*(dT) ( K )

x=0.1

x=0.3

x=1.2

BaFe12-xGaxO19

x=0.9 600

700

T(K)

Fig. 6

30

800

ACCEPTED MANUSCRIPT 200

x=0.3

BaFe12-xGaxO19 300K

x=0.9 x=0.6

x=1.2

100

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χin ( arb. un. )

150

x=0.1

a 0 0,5

1,0

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0,0

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50

1,5

2,0

B(T)

100

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x=0.3

300K

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χdif ( arb. un. )

200

BaFe12-xGaxO19

x=0.9

AC C

x=1.2 x=0.1

x=0.6

0

b

0,0

0,3

B(T)

Fig. 7

31

0,6

ACCEPTED MANUSCRIPT 0,3 c

a

e

640 50

600

580 0,0

0,1

BaFe12-xGaxO19

BaFe12-xGaxO19

0,4

0,8

0,0 0,0

1,2

40

BaFe12-xGaxO19

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Bmax ( T )

TC ( K )

620

MS ( emu/g )

0,2

30

0,4

0,8

x

1,2

T=300K

0,0

0,4

0,8

1,2

x

x b

d

f

2,0

HC ( kOe )

620

SC

2500

µmax ( arb. un. )

2000

600

BaFe12-xGaxO19

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ΘP ( K )

640

1500 0,0

0,4

0,8

1,2

BaFe12-xGaxO19

1,0

0,5

T=300K

0,0

0,4

0,8

x

x

1,5

AC C

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Fig. 8

32

1,2

BaFe12-xGaxO19 T=300K

0,0

0,4

0,8

x

1,2

ACCEPTED MANUSCRIPT a

ktr ( dB )

-5

-10

x=0.9

BaFe1-xGaxO19

x=0.1

-15

H=0kOe

35

40

45

50

x=1.2

55

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f ( GHz ) b

-10 BaFe1-xGaxO19 T=300K

-15

x=0.1

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-5

ktr ( dB )

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T=300K

H=2.5kOe

H=2kOe

35

40

AC C

ktr ( dB )

-10

-15

45

50

55

f ( GHz )

EP

c

-5

TE D

H=0.7kOe

H=0.7kOe

BaFe1-xGaxO19 T=300K

-20

H=3.5kOe

x=1.2 H=1.5kOe

35

40

45 f ( GHz )

Fig. 9

33

50

55

ACCEPTED MANUSCRIPT BaFe12-xGaxO19

50,4

H=0kOe 49,8

49,2 0,0

0,2

0,4

0,6

0,8

-18

0,0

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Ares ( dB )

H=0kOe

-17

0,2

1,2

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BaFe12-xGaxO19 T=300K

1,0

a

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x -16

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fres ( GHz )

T=300K

0,4

0,6

0,8

b 1,0

1,2

x

T=300K H=0kOe

AC C

Wres ( GHz )

4,8

EP

BaFe12-xGaxO19

4,2

c

3,6

0,0

0,2

0,4

0,6

0,8

x

Fig. 10

34

1,0

1,2

ACCEPTED MANUSCRIPT

kref ( dB )

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H=0 kOe

-10

H=2 kOe

-20

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BaFe10.8Ga1.2O19 T=300K

H=5 kOe

35

40

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-30

45

Fig. 11

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f ( GHz )

35

50

55

ACCEPTED MANUSCRIPT

56

BaFe12-xGaxO19 T=300K

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fres ( GHz )

54

52

50

x=1.2

x=0.3 x=0

0

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48

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x=0.1 x=0.9 x=0.6

1

2

H ( kOe )

AC C

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Fig. 12

36

3

4

ACCEPTED MANUSCRIPT

Ga doped barium hexaferrites were synthesized. Magnetic parameters were investigated.

Amplitude-frequency characteristics were obtained. Reflection and transmission coefficients were found.

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Effect of bias field on ferromagnetic resonance was investigated.