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Reducing the crystallite and particle size of SrFe12O19 with PVA by high energy ball milling
Accepted Manuscript Reducing the crystallite and particle size of SrFe12O19 with PVA by high energy ball milling F.N. Tenorio Gonzalez, I. Barajas, P. Vera Serna, F. Sánchez de Jesus, A.M. Bolarin Miró, A. Garrido Hernández, Martin Kusý PII:
S0925-8388(18)33189-X
DOI:
10.1016/j.jallcom.2018.08.297
Reference:
JALCOM 47385
To appear in:
Journal of Alloys and Compounds
Received Date: 7 February 2018 Revised Date:
28 August 2018
Accepted Date: 29 August 2018
Please cite this article as: F.N. Tenorio Gonzalez, I. Barajas, P. Vera Serna, F. Sánchez de Jesus, A.M. Bolarin Miró, A. Garrido Hernández, M. Kusý, Reducing the crystallite and particle size of SrFe12O19 with PVA by high energy ball milling, Journal of Alloys and Compounds (2018), doi: 10.1016/j.jallcom.2018.08.297. 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.
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Reducing the crystallite and particle size of SrFe12O19 with PVA by high energy ball milling
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F. N. Tenorio Gonzalez1,*, I. Barajas1, P. Vera Serna1, F. Sánchez de Jesus2, A. M. Bolarin Miró2, A. Garrido Hernández3, Martin Kusý4 1 División de ingenierías Universidad Politécnica de Tecamac Prolongación 5 de Mayo 10, Centro, C.P.55740 Estado de México 2 Área Académica de Ciencias de la Tierra y Materiales, Universidad Autónoma del Estado de Hidalgo, 42184, Mineral de la Reforma, Hidalgo, México 3 Universidad Tecnológica de Tecámac, 55740, Tecámac, Estado de México. 4 Slovak University of Technology in Bratislava, Faculty of Materials Science and Technology in Trnava, Jána Bottu No. 2781/25, 917 24 Trnava, Slovak Republic e-mail: [email protected] Abstract The effect of polyvinyl alcohol, PVA, on crystallite and particle sizes of strontium hexaferrite synthesized by high-energy ball milling followed by an annealing at 950°C is presented. Results of X-ray diffraction of (100-x)SrFe12O19@xPVA (0 ≤ x≤100) composites shown the presence of strontium hexaferrite in all samples, while the crystal
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structure of PVA is degraded due to the mechanical energy supplied from the milling process. However, the Infrared study (FTIR) indicated that the polymeric chain kept intact. Magnetic behavior, from vibrating sample magnetometry tests, shown a waist wasp type hysteresis loop, for all the composites SrFe12O19@PVA, confirming that both materials do
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not generate bonds, and there is only a mixture of materials. Finally, Rietveld refinement, SEM analysis, and particle size measurement allowed demonstrating that PVA reduces the
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crystallite and particle sizes at nanometers scale of strontium hexaferrite synthesized. Keywords: Mechanosynthesis, strontium hexaferrite, nanometer scale, waist wasp.
1. Introduction
The crystal structure of hexaferrites (M type) contains 64 ions per unit cell which crystallize in the P63/mmc space group [1], the Fe3+ ions in the hexaferrite structure, are occupying five different crystallographic sites such as three octahedral (2a, 12k and 4f2) one tetrahedral site (4f1) and one bypiramidal site (2b) [2], these ceramics magnets are of 1
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great technological and commercial significance due to their large crystalline anisotropy and high intrinsic coercivity [3]. Among ferrite materials, M-type hexaferrites are promising microwave absorbers since they have significant values of permeability. They absorb the microwave energy by lossy interactions of the wave magnetic field with their
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individual magnetization [4]
Strontium hexaferrite (SrFe12O19) has been synthesized by different methods, like sucrose precursor sol-gel technique [5], solution combustion method [6], Pechini, combustion [7], and ceramic method. Among others, mechanosynthesis is a simple method suitable for the
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production of powders composed of fine particles [8-9]. There are two ways to carried out the synthesis, dry and wet. Dry is preferable because the reactions are faster and with a
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lower pollution level that wet [10], but the wet produce particle sizes slightly lower that dry and a specific surface higher [11]. Generally the mechanosynthesis process is used to synthetize materials with particle size in magnitude order of micrometers; in recent years the PVA has been used to encapsulate materials with square structure, the results showed that the polymer help to obtain monodisperse materials and reduce the particle size using the chemical precipitation method [12].
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Some research studies are focused in the reduction of crystallite and particle size of magnetic materials, due to the new possible applications, as for instance, the nanocrystalline strontium hexaferrite powder, is a promising material for use as microwave absorbers in the gigahertz range [13-16]. In addition, the nanometric particle size with
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superparamagnetic properties can be used for high-density information storage, hyperthermia, and several clinical trials to detect liver and lymph node tumors, as well as inflammatory and degenerative diseases [12-14]. Moreover, the investigation of
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combinations of the ferrite fillers has also resulted in the fabrication of some efficient composite microwave absorbers. In specific, the minimum reflection coefficient of -26.4 dB and the maximum bandwidth of 2.7 GHz at the level of -10 dB were achieved by a ternary or binary ferrite filler mixture, respectively, with 45 wt% total loading and layer thickness of 5 mm [15]. In reference to PVA, it is a synthetic water-soluble hydrophilic polymer widely used in adhesives, emulsificants, in the textile, paper industry applications, in the attainment of amphiphilic membranes for enzyme immobilization, pharmaceutical and biomedical 2
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applications for controlled drug release tests due to its degradable and non-toxic properties [16] also PVA has been used as encapsulating polymer during the synthesis of different materials as Silver-doped titanium dioxide [17], silver nanoparticles [18], zinc sulphide, [19] and Natural Pesticide [20].
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Taking into account the relevance of particle size on the magnetic behavior of materials, the deal of this work is to demonstrate that is possible to reduce the particle size of strontium hexaferrite powder synthesized by high-energy ball milling followed by an annealing by using PVA as controlling agent during the mechanical milling. Besides, it is described the
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crystal structure and physical properties of strontium hexaferrite particles, encapsulated
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with PVA.
2. Experimental part.
Strontium carbonate (SrCO3) and iron oxide (Fe2O3) were used to synthetized the strontium hexaferrite, both materials were purchased from Sigma-Aldrich; the powders used in the synthesis were analytical grade and used as-received without a purification. For obtaining the composite it was used polyvinyl alcohol (PVA) average Mw 146,000-186,000, 87-89%
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hydrolyzed.
In order to synthesize strontium hexaferrite, oxide powders (precursors) were mixed in a stoichiometric ratio, following the equation: ∆
(eq. 1)
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+ 6 → +
A total of 5 g of precursor’s mixture was loaded along with steel balls of 1.27 cm of
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diameter in a cylindrical steel vial (50 cm3) (steel/steel, S/S) at room temperature in air atmosphere and milled for 5 h, using a shaker mixer mill (SPEX model 8000D). The ball to powder weight ratio was 10:1. The activated milled powder were annealed at 950°C during 2 hours at air atmosphere, using a heating rate of 10°/min, and cooling at room temperature as reported previously [8-9, 21]. In order to obtain the SrFe12O19@PVA composites, stoichiometric mixtures of powder of SrFe12O19 and PVA to obtain different composition of (100-x)SrFe12O19@xPVA (0 ≤
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x≤100) together with 17 balls of sapphire were high energy ball milled for 3 h using a ball to powder weight ratio of 10:1. The obtained composites powder were characterized by X-ray diffraction (XRD) using a Bruker D8 advance diffractometer with CuKα1 (λ=1.5418740 Å) radiation. Patterns were
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collected in a 2θ interval of 15-75° with increments of 0.02 (2θ). FT-IR study was obtained by a Perkin Elmer Spectrum two FTIR Spectrometer mode ATR. Scanning Electron Microscopy (SEM) using a JEOL 7600 F with low vacuum mode which raises the pressure in the specimen chamber to neutralize the charging of sample surfaces for enabling
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observation of non-conductive samples, SEM helped to determinate the morphology and qualitatively the particle size. ImageJ software was used to transform pixels in nanometer
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and check the particles sizes also this software transform the intensity of lights in pics and simulate figures three-dimensional to check the particles surface. Particle diameter was carried up using a NanoBrook 90Plus Particle Size Analyzer, to prepare each sample, the powder was immersed in distilled water in order to degrade the polyvinyl alcohol and thus observe the particle size of the strontium hexaferrite. Magnetization studies were carried out at room temperature using a MicroSense EV7 vibrating sample magnetometer (VSM)
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with a maximum field of ±18 kOe.
3. Results and discussion
The X-ray diffraction patterns of composite with different compositions (x) are shown in
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Fig 1. As can be observed, the XRD pattern corresponding to the sample of pure strontium hexaferrite (x=0) shows the presence of strontium hexaferrite as primary phase (SrFe12O19,
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COD: 1006000, P63/mmc) [22]) together with small amounts of hematite (Fe2O3, COD: 1011240, R3c: R), as secondary phase [22]). The strontium hexaferrite was index with the follow equation:
=
( )
+
(eq. 2)
Where d is d-spacing value, a and c are the lattice values and h k l are the Miller index. As can be observe, the pure stromtium hexaferrite (x=0) show a high diffraction peaks intensity, due to presence of crystalline material (strontium hexaferrite), while for SrFe12O19@PVA composites, the intensity of the diffraction peaks decrease as the PVA presence increase because the mechanical energy modified the ordering of crystal changing 4
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from a crystalline to amorphous material. To confirm the previous statement, a comparison between the PVA milled for 3 h and an un-milled sample is presented in Figure 1. As can be observed, the sample milled does not show diffraction peaks, attributed to an amorphous material. While, the un-milled sample shows a crystalline phase with high intensity, the
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most intensity peaks are (100) and (200), whose disappear when the powder is milled. However, for composites with lower contents of PVA (x=75 and 50), these diffraction peaks remain, due to the strontium hexaferrite cushion the pounding of balls and reduce the energy supplied in the mill.
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The table 1 shows the XRD patterns corresponding to pure strontium hexaferrite (x=0) refined by the Rietveld method to obtain the crystallographic parameters. The Rietveld
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results shows that the percentage of strontium hexaferrite is 93.12% with a crystallite size of 117.66 nm and a low microstrain value of 3.326E-7 to conform the effectivity of refinement study, we present the standard R-factors where χ2 is the goodness of fit, Rwp is the weighted residual and R(exp) is equal to Rwp/√ χ2.
The XRD pattern of composites (100-x)SrFe12O19@xPVA (0 ≤ x≤100) were not refined,
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because the polyvinyl alcohol pattern (PVA, P21/m) is not in the data base, but the XRD patterns were index using the values of a monoclinic unit cell with lattice parameters a=7.81Å, b=2.52Å, c=5.51Å and β=91°42´ reported by Bunn [23] following the next equation:
=
+
+
!
"
#
!$
# (1'() β + 2cosβ)/
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(eq. 3)
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The crystallite size was obtained using the Scherrer equation that can be written as following. 0=
12
3$ 4
(eq. 4)
Where 0.94 is K constant which depends on values of reflection indices (hkl) τ is the crystallite size, λ is the X ray wavelength, β is the full weight half maximum (FWHM) and θ is the Bragg angle. Fig. 2 shows the effect of polymer on the strontium hexaferrite crystallite size, as can be observed in sample SrFe12O19 100%@PVA 0% (S100-P0) the crystallite size is 107 nm, this value is approximate to the obtained by Rietvel refinement 5
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(117 nm) and the difference between both is due to instrumental value. The figure indicate that the crystallite size decrease when the PVA is add to form the composite, the best ratio value is 50:50 in weight.
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About of the XRD pattern of pure strontium hexaferrite (x=0), the relative intensity of the diffraction peaks change, in reference to bulk SrFe12O19 sample. It can be observed in the XRD pattern higher relative intensity for the plane (114). While, for the composite samples, the most intense peak is the corresponding to the plane (107). As it is known, the relative
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intensity of the diffraction peaks is a function of the crystal structure, and depends on factors such as the ionic scattering factor and the structure factor [24]. The change in
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relative intensity in the diffraction planes is attributed to the preferred orientation of the strontium hexaferrite crystallite due to the method of synthesis, high-energy ball milling using a control agent (PVA) that promotes the preferential distortion of the unit cell of the material in a specific crystal direction. This effect was previously observed by Stingaciu et al. [25], who found a preferred orientation in the (107) diffraction plane for strontium hexaferrite synthesized using high-energy ball milling. In addition, the variation of the
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relative intensity is also affected by the modification of the lattice parameters, as can be observe in the fig 2, where clearly it is detected a decrease in the lattice parameter “a” and at the same time, an increase in the lattice parameter “c” as the PVA percentage increases.
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FTIR was used to analyze the chemical evolution of PVA and its possible interaction with strontium hexaferrite particles, the results are shown in Figure 3. This Figure depict the transmission peaks of PVA are represented with red color, and included 3300 cm-1
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(stretching of OH), 2940 cm-1 (asymmetric stretching of CH2), 2910 cm-1 (asymmetric stretching of CH2), 2840 cm-1 (stretching of CH), 1430 cm-1 (bending of CH2), 1731 cm-1 (stretching of C=O) from acetate group, 1430 cm-1 (bending of CH2), 1376 cm-1 (wagging of CH2), 1326 cm-1 (bending of CH+OH), 1087 cm-1 (stretching of CO), 1030, 917 cm-1 (rooking of CH2), 851 cm-1 (stretching of C-C) and the last broad band from 760 to 500 cm-1 correspond rooking of OH [26-28]. The transition peaks of strontium hexaferrite are represented of blue color and correspond to MO vibration modes, the bands included 546
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cm-1 (bending Sr-O) and 586 cm-1 (stretching Fe-O) [25]. Finally the band at 2350 cm-1 (antisymmetric stretching CO2) corresponds to carbone dioxide of atmosphere [29]. The FTIR results allow concluding that the mechanical energy supplied by high energy ball
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milling change the crystal structure of PVA forming an amorphous material but the molecule remains intact, which permit the encapsulation of strontium hexaferrite, conforming a (100-x)SrFe12O19@xPVA composite. All peaks of spectroscopy show a sequence of transmission diminution due to the percentage used in the preparation of
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composite and we cannot observe an unusual behavior in the FTIR studies, for this reason it can be conclude that the polymer does no interact with the strontium hexaferrite, coexist
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two phases in same powder as a mixture.
To confirm the previews statement, a Vibrating Sample Magnetometry study was carried out, the results are shown in the Fig. 4. The hysteresis loop of pure strontium hexaferrite (x=0) has a typical behavior of a hard ferromagnetic material with a coercive field of 5.6 kOe and a specific magnetic saturation of 40 emu/g. After adding PVA to obtain the
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composite of different compositions, from 25 to 75 % wt. of PVA, the magnetic hysteresis showed a loop type wasp waist. Finally, the sample of pure PVA did not show coercivity and magnetic saturation neither.
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The wasp waist type hysteresis loops indicate that two phases or materials coexist in a same powder confirming that there is not any kind of chemical interactions between them. The > 29$: where 567 is the model used for exchange coupled of this composite is 567 :
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nanoscopic dimensions of the strontium hexaferrite phase and 29$ indicate that the estimated domain wall thickness of the polymer phase should be on the order of twice greater [30-32], the Fig. 5 shows the ordering of composite, where the diameter of particles is more lest that twice the separation between the particles this produce an abrupt fall just where the coercive field is about zero. Other effect of polymer matrix is the diminution in the magnetization saturation but this effect can be explained with the mixture theory Ms=fp*Mp+fs*Ms where fp and fs are the fraction of polyvinyl alcohol and strontium hexaferrite phases and Mp and Ms are the magnetization value of two phases. The preview 7
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formula indicate that the total saturation magnetization depending of the percentage of phases, for this reason the magnetization value of hysteresis loop decrease when the polymer percentage increase.
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The Fig. 6 shows the morphology of composites with different content of PVA. The sample of PVA (S0-P100) presents a morphology type fluted granules of large sizes of 1.2 mm, the first zoom shows an irregular surface of PVA with some flat areas for this reason we simulate a small flat area and the figure shows a wavy surface. The sample of strontium
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hexaferrite (P0-S100) shows agglomerates with bigger particle size of 27 µm, to observe small particles we select and as can be observed the agglomerates contain spherical
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particles of strontium hexaferritas, to observe the particle surface we simulate an agglomerate of two particles and as can be observed the flat surface. Three composites (P75-S25, P50-S50 and P25-S75) confirm previous model suggested because three panoramic figures shows that the PVA is matrix and there are strontium hexaferrita particles distributed in each PVA granule. The zoom of three samples shows spherical particles of different sizes as can be observe particles is separated due to polymer and the
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sizes of strontium hexaferritas agglomerate is small in comparison with sample P0-S100. Finally a particle of each composite was simulated to describe the surface as can be observed the three particles have spherical tendency as strontium hexaferrite pure sample
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but the composites have ondule surface that confirm the encapsulation of ceramic particles.
In Fig. 7 is presented the particle size distribution of pure strontium hexaferrite powder (x=0). The continue curve correspond to the volume fraction, while the dashed curve is the
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accumulate volume fraction. The obtained results indicate that 80% of particles have smaller diameter than 21 µm, and the 20% of particle volume have diameter from 21 to 40 µm. Besides, it can be observed that the average particles size is 8.6 µm, in good agreement with the data obtained by SEM.
In the SEM study we observed particles with high size because the PVA encapsulated the strontium hexaferrite particles but when we dispersed the powders in distilled water, the PVA was dissolved and the strontium hexaferrite particles was liberated so that in this 8
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study the particle size is only of strontium hexaferrite. Fig. 8 shows the effect of encapsulation add mechanical energy to form a composite in the particle size of strontium hexaferrite. As can be observed when added 25% of PVA is, the average particles size is 87 nm, but when is added 50% of PVA, the particle size increase up to 115 nm, and when is
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added 75% of PVA, the particle increase even more up to 130 nm. This behavior is similar to the evolution of the crystallite size, and these results indicate that there is an optimal ratio to decrease the crystallite and particle size. In the analyzed experimental conditions, the best ratio was 25% of polyvinyl alcohol and 75% of strontium hexaferrite, because with
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this ratio powders in scale nanometric are obtained.
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4. Conclusions.
The strontium hexaferrite was synthesized by the high-energy ball milling for 5 hours and subsequently annealing at 950°C, the crystallite and particle size were reduced by the encapsulation of SrFe12O19 with polyvinyl alcohol during high mechanical energy for 3 hours. The results of FTIR and magnetic properties indicated that the composite obtained by PVA and strontium hexaferite did not have interaction between particles and only
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coexist the particles in a same powder. The crystallite and particle measures showed a reduction in the size in all PVA-strontium hexaferrite compositions but the best relation to reduce the crystallite and particles size is 25% of PVA and 75% of strontium hexaferrite for two reasons: (a) the crystallite size is reduced from 107 nm to 40 nm, and (b) there is the
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only composition that produce particles in nonmetric scale, because we obtained particles
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of 87 nm when we dissolved the polymer in distilled water.
5. References
[1] Guerrero, A. L., Mirabal-García, M., Palomares-Sánchez, S. A., & Martínez, J. R. Effect of Pb on the magnetic interactions of the M-type hexaferrites. Journal of Magnetism and Magnetic Materials, 399 (2016) 41–45. [2] Yang, Y., Wang, F., Liu, X., Shao, J., Feng, S., Huang, D., & Li, M. The effect of Bi substitution on the microstructure and magnetic properties of the Sr0.4Ba0.3La0.3Fe12XBiXO19 hexagonal ferrites. Journal of Magnetism and Magnetic Materials, 422 (2017) 209–215.
9
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[3] Wang, H. Z., Hai, Y. N., Yao, B., Xu, Y., Shan, L., Xu, L. & Wang, Q. H. Tailoring structure and magnetic characteristics of strontium hexaferrite via Al doping engineering. Journal of Magnetism and Magnetic Materials, 422 (2017) 204-208. [4] S.S.S Afghahi, M. Jafarian, Y. Atassi. Novel approach for designing a thin and broadband microwave absorber in Ku band based on substituted M-hexaferrites Materials. Journal of Magnetism and Magnetic Materials 419 (2016) 62–67. [5] Narang, S. B., Pubby, K., Chawla, S. K., & Kaur, P. Origin of absorption peaks in reflection loss spectrum in Ku- frequency band of Co-Zr substituted strontium hexaferrites prepared using sucrose precursor. Journal of Magnetism and Magnetic Materials, 426 (2017) 202-205. [6] Abasht, B, Mohammad Mirkazemi, S. and Beitollahi, A. Solution combustion synthesis of Ca hexaferrite using glycine fuel. Journal of Alloys and Compounds, 708 (2017) 337-343. [7] Ramírez, A. E., Solarte, N. J., Singh, L. H., Coaquira, J. A., & Gaona, S. Investigation of the magnetic properties of SrFe12O19 synthesized by the Pechini and combustion methods. Journal of Magnetism and Magnetic Materials, 438 (2017) 100–106. [8] F. Sánchez-De Jesús, A.M. Bolarín-Miró, C.A. Cortés-Escobedo, R. Valenzuela, S. Ammar, Mechanosynthesis, crystal structure and magnetic characterization of M-type SrFe12O19, Ceram. Int. 40 (2014) 4033–4038. [9] F.N. Tenorio Gonzalez, A.M. Bolarín Miró, F. Sánchez De Jesús, C.A. Cortés Escobedo, S. Ammar, Mechanism and microstructural evolution of polyol mediated synthesis of nanostructured M-type SrFe12O19, J. Magn. Magn. Mater. 407 (2016) 188– 194. [10] El Briak-BenAbdeslam, H., Ginebra, M. P., Vert, M., & Boudeville, P. Wet or dry mechanochemical synthesis of calcium phosphates Influence of the water content on DCPD–CaO reaction kinetics. Acta Biomaterialia, 4 (2008) 378–386. [11] Neamţu, B. V., Chicinaş, H. F., Marinca, T. F., Isnard, O., Pană, O., & Chicinaş, I. Formation of Fe-based alloy via wet mechanical alloying assisted by PCA decomposition. Materials Chemistry and Physics, 183 (2016) 83–92. [12] Nguyen, T. P., Le, A. D., Vu, T. B., & Lam, Q. V. Investigations on Photoluminescence Enhancement of Poly(vinyl alcohol)-encapsulated Mn-doped ZnS Quantum dots. Journal of Luminescence. (2017) [13] Drmota, A, Drofenik, M. and Znidarsic, A. Synthesis and characterization of nanocrystalline strontium hexaferrite using the co-precipitation and microemulsion methods with nitrate precursors. Ceramics International, 38 (2012) 973-979. [14] Pullar, R. C. Hexagonal ferrites: A review of the synthesis, properties and applications of hexaferrite ceramics. Progress in Materials Science, 57 (2012) 1191-1334. [15] S.S.S Afghahi, M. Jafarian, Y. Atassi, C. A. Stergiou. Single and double-layer composite microwave absorbers with hexaferrite BaZn0.6Zr0.3X0.3Fe10.8O19 (X= Ti, Ce, Sn) powders. Materials Chemistry and Physics 186 (2017) 584-591. 10
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[16] Reis, E. F. D., Campos, F. S., Lage, A. P., Leite, R. C., Heneine, L. G., Vasconcelos, W. L., Mansur, H. S. (2006). Synthesis and characterization of poly (vinyl alcohol) hydrogels and hybrids for rMPB70 protein adsorption. Materials Research, 9(2), 185191. [17] Shende, P., Oza, B., & Gaud, R. S. (2018). Silver-doped titanium dioxide nanoparticles encapsulated in chitosan–PVA film for synergistic antimicrobial activity. International Journal of Polymeric Materials and Polymeric Biomaterials, 1-7. [18] Chandran, S., Ravichandran, V., Chandran, S., Chemmanda, J., & Chandarshekar, B. (2016). Biosynthesis of PVA encapsulated silver nanoparticles. Journal of applied research and technology, 14(5), 319-324. [19] Ghosh, G., Naskar, M. K., Patra, A., & Chatterjee, M. (2006). Synthesis and characterization of PVP-encapsulated ZnS nanoparticles. Optical Materials, 28(8-9), 1047-1053. [20] Rashidzadeh, A., Olad, A., Salari, D., & Jalil Hejazi, M. (2014). On the encapsulation of natural pesticide using polyvinyl alcohol/alginate–montmorillonite nanocomposite for controlled release application. Polymer Engineering & Science, 54(12), 2707-2714. [21] Tenorio-González, F. N., Bolarín-Miró, A. M., Sánchez-De Jesús, F., Vera-Serna, P., Menéndez-González, N., Sánchez-Marcos, J. Crystal structure and magnetic properties of high Mn-doped strontium hexaferrite. Journal of Alloys and Compounds. 695 (2017) 2083-2090. [22] Gražulis, S., Daškevič, A., Merkys, A., Chateigner, D., Lutterotti, L., Quiros, M. & Le Bail, A. Crystallography Open Database (COD): an open-access collection of crystal structures and platform for world-wide collaboration. Nucleic acids research, 40(D1) (2011) D420-D427. [23] Bunn, C. W. Crystal structure of polyvinyl alcohol. 161(4102) (1948) 929-930. [24] Guerrero-Serrano, A. L., Palomares-Sánchez, S. A., Mirabal-García, M., & MatutesAquino, J. A. Magneto-Structural Characterization of Strontium Substituted Lead Hexaferrite. J Supercond Nov Magn, 25 (2012) 1223–1228. [25] Stingaciu M., Topole M., McGuiness P., Christensen M. Magnetic properties of ballmilled SrFe12O19 particles consolidated by Spark-Plasma Sintering. Sci. Rep. 5 (2015)
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14112.
[26] Cheng-Ming, T, Yi-Hung, T and Shan-Hui, H. Poly(vinil alcohol) Nonocomposites reinforced with bamboo chearcol nanoparticles: mineralization bihabior and characterization. Materials research, 8 (2015) 4895-4911. [27] Abd El-Kander, K M and Orabi, A. S. Spectroscopi behabior of poly (vinyl alcohol) films with diferent molecuar weights. Polymer testing, 21 (2002) 591-595. [28] Mansur, H. S., Sadahira, C. M., Souza, A. N., & Mansur, A. A. FTIR spectroscopy characterization of poly (vinyl alcohol) hydrogel with different hydrolysis degree and chemically crosslinked with glutaraldehyde. Materials Science and Engineering C,1 28 (2008) 539– 548.
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[29] Seyyed Afghahi, S S, Jafarian, M and Atassi, Y. Microstructural and magnetic studies on BaMgxZn2xFe12-4XO19 (X=Zr,Ce,Sn) prepared via mechanical activation method to act as a microwave absorber in X-band. Journal of Magnetism and Magnetic Materials 406 (2016) 184–191. [30] Jimenez-Villacorta, F and Lewis, L. H. Advanced Permanent Magnetic Materials. Nanomagnetism (2014) 161-186. [31] Rocha, M. J. S., Theophilo, K. R. B., Denardin, J. C., Vasconcelos, I. F., Araújo, E. B., & Sombra, A. S. B. Ferrimagnetism and Ferroelectricity of the Composite Matrix: SrBi2Nb2O9 (SBN) X-BaFe12O19 (BFO) 100–X. Materials Science and Applications 3 (2012). [32] Taiping, Xie, Longjun, Xu and Chenglun, Liu. Synthesis and properties of composite magnetic material SrCoxFe12-XO19 (x=0-0.3). Powder Technology, 232 (2012).
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Table 1: Rietveld refinement of sample S100-P0.
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Tables and Figures
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Figure 1: X-ray diffraction patterns of (100-x) SrFe12O19@xPVA composites with x from 0 to 100 % wt.
Figure 2: Effect of PVA on the strontium hexaferrite crystal size. Figure 3: X diffraction patterns of composites with different composition. Figure 4: VSM of composites with different composition of strontium hexaferite and PVA.
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Figure 5: Model of composite PVA with hysteresis loops type wasp waist. Figure 6: Morphology of composites with different ratio between PVA and strontium hexaferrite.
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Figure 7: Particle size distribution of pure strontium hexaferrite powder (x=0).
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Figure 8: Particle size of composite samples.
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Table 1: Rietveld refinement of sample S100-P0.
0.5881 nm
Lattice c Crystal size
2.3069 nm 117.656 nm
Parameters % Wt. Fe2O3 Lattice a=b=c
Values 6.876 % 0.5428 nm
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Values 93.124 %
Parameters % wt. SrFe12O19 Lattice a=b
R(exp)-factor
0.1218
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Microstrain 3.3264x10-7 Rwp-factor
Crystal 146.101 nm size Microstrain 1.4932x10-5 0.10958
0.8096
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Highlights
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SrFe12O19@PVA with different ratio were obtained by high energy ball milling using sapphire balls during 3 hours. The effect of mechanical mill in the PVA material is reported. A magnetic model of SrFe12O19@PVA wasp waist is proposed. Nanoparticles of strontium hexaferrite were obtained and liberated in water using PVA as encapsulator. The best ratio is 25% of PVA and 75% of strontium hexaferrite.
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S0925-8388(18)33189-X
DOI:
10.1016/j.jallcom.2018.08.297
Reference:
JALCOM 47385
To appear in:
Journal of Alloys and Compounds
Received Date: 7 February 2018 Revised Date:
28 August 2018
Accepted Date: 29 August 2018
Please cite this article as: F.N. Tenorio Gonzalez, I. Barajas, P. Vera Serna, F. Sánchez de Jesus, A.M. Bolarin Miró, A. Garrido Hernández, M. Kusý, Reducing the crystallite and particle size of SrFe12O19 with PVA by high energy ball milling, Journal of Alloys and Compounds (2018), doi: 10.1016/j.jallcom.2018.08.297. 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.
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Reducing the crystallite and particle size of SrFe12O19 with PVA by high energy ball milling
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F. N. Tenorio Gonzalez1,*, I. Barajas1, P. Vera Serna1, F. Sánchez de Jesus2, A. M. Bolarin Miró2, A. Garrido Hernández3, Martin Kusý4 1 División de ingenierías Universidad Politécnica de Tecamac Prolongación 5 de Mayo 10, Centro, C.P.55740 Estado de México 2 Área Académica de Ciencias de la Tierra y Materiales, Universidad Autónoma del Estado de Hidalgo, 42184, Mineral de la Reforma, Hidalgo, México 3 Universidad Tecnológica de Tecámac, 55740, Tecámac, Estado de México. 4 Slovak University of Technology in Bratislava, Faculty of Materials Science and Technology in Trnava, Jána Bottu No. 2781/25, 917 24 Trnava, Slovak Republic e-mail: [email protected] Abstract The effect of polyvinyl alcohol, PVA, on crystallite and particle sizes of strontium hexaferrite synthesized by high-energy ball milling followed by an annealing at 950°C is presented. Results of X-ray diffraction of (100-x)SrFe12O19@xPVA (0 ≤ x≤100) composites shown the presence of strontium hexaferrite in all samples, while the crystal
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structure of PVA is degraded due to the mechanical energy supplied from the milling process. However, the Infrared study (FTIR) indicated that the polymeric chain kept intact. Magnetic behavior, from vibrating sample magnetometry tests, shown a waist wasp type hysteresis loop, for all the composites SrFe12O19@PVA, confirming that both materials do
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not generate bonds, and there is only a mixture of materials. Finally, Rietveld refinement, SEM analysis, and particle size measurement allowed demonstrating that PVA reduces the
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crystallite and particle sizes at nanometers scale of strontium hexaferrite synthesized. Keywords: Mechanosynthesis, strontium hexaferrite, nanometer scale, waist wasp.
1. Introduction
The crystal structure of hexaferrites (M type) contains 64 ions per unit cell which crystallize in the P63/mmc space group [1], the Fe3+ ions in the hexaferrite structure, are occupying five different crystallographic sites such as three octahedral (2a, 12k and 4f2) one tetrahedral site (4f1) and one bypiramidal site (2b) [2], these ceramics magnets are of 1
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great technological and commercial significance due to their large crystalline anisotropy and high intrinsic coercivity [3]. Among ferrite materials, M-type hexaferrites are promising microwave absorbers since they have significant values of permeability. They absorb the microwave energy by lossy interactions of the wave magnetic field with their
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individual magnetization [4]
Strontium hexaferrite (SrFe12O19) has been synthesized by different methods, like sucrose precursor sol-gel technique [5], solution combustion method [6], Pechini, combustion [7], and ceramic method. Among others, mechanosynthesis is a simple method suitable for the
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production of powders composed of fine particles [8-9]. There are two ways to carried out the synthesis, dry and wet. Dry is preferable because the reactions are faster and with a
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lower pollution level that wet [10], but the wet produce particle sizes slightly lower that dry and a specific surface higher [11]. Generally the mechanosynthesis process is used to synthetize materials with particle size in magnitude order of micrometers; in recent years the PVA has been used to encapsulate materials with square structure, the results showed that the polymer help to obtain monodisperse materials and reduce the particle size using the chemical precipitation method [12].
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Some research studies are focused in the reduction of crystallite and particle size of magnetic materials, due to the new possible applications, as for instance, the nanocrystalline strontium hexaferrite powder, is a promising material for use as microwave absorbers in the gigahertz range [13-16]. In addition, the nanometric particle size with
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superparamagnetic properties can be used for high-density information storage, hyperthermia, and several clinical trials to detect liver and lymph node tumors, as well as inflammatory and degenerative diseases [12-14]. Moreover, the investigation of
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combinations of the ferrite fillers has also resulted in the fabrication of some efficient composite microwave absorbers. In specific, the minimum reflection coefficient of -26.4 dB and the maximum bandwidth of 2.7 GHz at the level of -10 dB were achieved by a ternary or binary ferrite filler mixture, respectively, with 45 wt% total loading and layer thickness of 5 mm [15]. In reference to PVA, it is a synthetic water-soluble hydrophilic polymer widely used in adhesives, emulsificants, in the textile, paper industry applications, in the attainment of amphiphilic membranes for enzyme immobilization, pharmaceutical and biomedical 2
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applications for controlled drug release tests due to its degradable and non-toxic properties [16] also PVA has been used as encapsulating polymer during the synthesis of different materials as Silver-doped titanium dioxide [17], silver nanoparticles [18], zinc sulphide, [19] and Natural Pesticide [20].
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Taking into account the relevance of particle size on the magnetic behavior of materials, the deal of this work is to demonstrate that is possible to reduce the particle size of strontium hexaferrite powder synthesized by high-energy ball milling followed by an annealing by using PVA as controlling agent during the mechanical milling. Besides, it is described the
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crystal structure and physical properties of strontium hexaferrite particles, encapsulated
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with PVA.
2. Experimental part.
Strontium carbonate (SrCO3) and iron oxide (Fe2O3) were used to synthetized the strontium hexaferrite, both materials were purchased from Sigma-Aldrich; the powders used in the synthesis were analytical grade and used as-received without a purification. For obtaining the composite it was used polyvinyl alcohol (PVA) average Mw 146,000-186,000, 87-89%
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hydrolyzed.
In order to synthesize strontium hexaferrite, oxide powders (precursors) were mixed in a stoichiometric ratio, following the equation: ∆
(eq. 1)
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+ 6 → +
A total of 5 g of precursor’s mixture was loaded along with steel balls of 1.27 cm of
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diameter in a cylindrical steel vial (50 cm3) (steel/steel, S/S) at room temperature in air atmosphere and milled for 5 h, using a shaker mixer mill (SPEX model 8000D). The ball to powder weight ratio was 10:1. The activated milled powder were annealed at 950°C during 2 hours at air atmosphere, using a heating rate of 10°/min, and cooling at room temperature as reported previously [8-9, 21]. In order to obtain the SrFe12O19@PVA composites, stoichiometric mixtures of powder of SrFe12O19 and PVA to obtain different composition of (100-x)SrFe12O19@xPVA (0 ≤
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x≤100) together with 17 balls of sapphire were high energy ball milled for 3 h using a ball to powder weight ratio of 10:1. The obtained composites powder were characterized by X-ray diffraction (XRD) using a Bruker D8 advance diffractometer with CuKα1 (λ=1.5418740 Å) radiation. Patterns were
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collected in a 2θ interval of 15-75° with increments of 0.02 (2θ). FT-IR study was obtained by a Perkin Elmer Spectrum two FTIR Spectrometer mode ATR. Scanning Electron Microscopy (SEM) using a JEOL 7600 F with low vacuum mode which raises the pressure in the specimen chamber to neutralize the charging of sample surfaces for enabling
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observation of non-conductive samples, SEM helped to determinate the morphology and qualitatively the particle size. ImageJ software was used to transform pixels in nanometer
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and check the particles sizes also this software transform the intensity of lights in pics and simulate figures three-dimensional to check the particles surface. Particle diameter was carried up using a NanoBrook 90Plus Particle Size Analyzer, to prepare each sample, the powder was immersed in distilled water in order to degrade the polyvinyl alcohol and thus observe the particle size of the strontium hexaferrite. Magnetization studies were carried out at room temperature using a MicroSense EV7 vibrating sample magnetometer (VSM)
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with a maximum field of ±18 kOe.
3. Results and discussion
The X-ray diffraction patterns of composite with different compositions (x) are shown in
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Fig 1. As can be observed, the XRD pattern corresponding to the sample of pure strontium hexaferrite (x=0) shows the presence of strontium hexaferrite as primary phase (SrFe12O19,
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COD: 1006000, P63/mmc) [22]) together with small amounts of hematite (Fe2O3, COD: 1011240, R3c: R), as secondary phase [22]). The strontium hexaferrite was index with the follow equation:
=
( )
+
(eq. 2)
Where d is d-spacing value, a and c are the lattice values and h k l are the Miller index. As can be observe, the pure stromtium hexaferrite (x=0) show a high diffraction peaks intensity, due to presence of crystalline material (strontium hexaferrite), while for SrFe12O19@PVA composites, the intensity of the diffraction peaks decrease as the PVA presence increase because the mechanical energy modified the ordering of crystal changing 4
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from a crystalline to amorphous material. To confirm the previous statement, a comparison between the PVA milled for 3 h and an un-milled sample is presented in Figure 1. As can be observed, the sample milled does not show diffraction peaks, attributed to an amorphous material. While, the un-milled sample shows a crystalline phase with high intensity, the
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most intensity peaks are (100) and (200), whose disappear when the powder is milled. However, for composites with lower contents of PVA (x=75 and 50), these diffraction peaks remain, due to the strontium hexaferrite cushion the pounding of balls and reduce the energy supplied in the mill.
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The table 1 shows the XRD patterns corresponding to pure strontium hexaferrite (x=0) refined by the Rietveld method to obtain the crystallographic parameters. The Rietveld
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results shows that the percentage of strontium hexaferrite is 93.12% with a crystallite size of 117.66 nm and a low microstrain value of 3.326E-7 to conform the effectivity of refinement study, we present the standard R-factors where χ2 is the goodness of fit, Rwp is the weighted residual and R(exp) is equal to Rwp/√ χ2.
The XRD pattern of composites (100-x)SrFe12O19@xPVA (0 ≤ x≤100) were not refined,
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because the polyvinyl alcohol pattern (PVA, P21/m) is not in the data base, but the XRD patterns were index using the values of a monoclinic unit cell with lattice parameters a=7.81Å, b=2.52Å, c=5.51Å and β=91°42´ reported by Bunn [23] following the next equation:
=
+
+
!
"
#
!$
# (1'() β + 2cosβ)/
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(eq. 3)
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The crystallite size was obtained using the Scherrer equation that can be written as following. 0=
12
3$ 4
(eq. 4)
Where 0.94 is K constant which depends on values of reflection indices (hkl) τ is the crystallite size, λ is the X ray wavelength, β is the full weight half maximum (FWHM) and θ is the Bragg angle. Fig. 2 shows the effect of polymer on the strontium hexaferrite crystallite size, as can be observed in sample SrFe12O19 100%@PVA 0% (S100-P0) the crystallite size is 107 nm, this value is approximate to the obtained by Rietvel refinement 5
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(117 nm) and the difference between both is due to instrumental value. The figure indicate that the crystallite size decrease when the PVA is add to form the composite, the best ratio value is 50:50 in weight.
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About of the XRD pattern of pure strontium hexaferrite (x=0), the relative intensity of the diffraction peaks change, in reference to bulk SrFe12O19 sample. It can be observed in the XRD pattern higher relative intensity for the plane (114). While, for the composite samples, the most intense peak is the corresponding to the plane (107). As it is known, the relative
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intensity of the diffraction peaks is a function of the crystal structure, and depends on factors such as the ionic scattering factor and the structure factor [24]. The change in
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relative intensity in the diffraction planes is attributed to the preferred orientation of the strontium hexaferrite crystallite due to the method of synthesis, high-energy ball milling using a control agent (PVA) that promotes the preferential distortion of the unit cell of the material in a specific crystal direction. This effect was previously observed by Stingaciu et al. [25], who found a preferred orientation in the (107) diffraction plane for strontium hexaferrite synthesized using high-energy ball milling. In addition, the variation of the
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relative intensity is also affected by the modification of the lattice parameters, as can be observe in the fig 2, where clearly it is detected a decrease in the lattice parameter “a” and at the same time, an increase in the lattice parameter “c” as the PVA percentage increases.
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FTIR was used to analyze the chemical evolution of PVA and its possible interaction with strontium hexaferrite particles, the results are shown in Figure 3. This Figure depict the transmission peaks of PVA are represented with red color, and included 3300 cm-1
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(stretching of OH), 2940 cm-1 (asymmetric stretching of CH2), 2910 cm-1 (asymmetric stretching of CH2), 2840 cm-1 (stretching of CH), 1430 cm-1 (bending of CH2), 1731 cm-1 (stretching of C=O) from acetate group, 1430 cm-1 (bending of CH2), 1376 cm-1 (wagging of CH2), 1326 cm-1 (bending of CH+OH), 1087 cm-1 (stretching of CO), 1030, 917 cm-1 (rooking of CH2), 851 cm-1 (stretching of C-C) and the last broad band from 760 to 500 cm-1 correspond rooking of OH [26-28]. The transition peaks of strontium hexaferrite are represented of blue color and correspond to MO vibration modes, the bands included 546
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cm-1 (bending Sr-O) and 586 cm-1 (stretching Fe-O) [25]. Finally the band at 2350 cm-1 (antisymmetric stretching CO2) corresponds to carbone dioxide of atmosphere [29]. The FTIR results allow concluding that the mechanical energy supplied by high energy ball
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milling change the crystal structure of PVA forming an amorphous material but the molecule remains intact, which permit the encapsulation of strontium hexaferrite, conforming a (100-x)SrFe12O19@xPVA composite. All peaks of spectroscopy show a sequence of transmission diminution due to the percentage used in the preparation of
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composite and we cannot observe an unusual behavior in the FTIR studies, for this reason it can be conclude that the polymer does no interact with the strontium hexaferrite, coexist
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two phases in same powder as a mixture.
To confirm the previews statement, a Vibrating Sample Magnetometry study was carried out, the results are shown in the Fig. 4. The hysteresis loop of pure strontium hexaferrite (x=0) has a typical behavior of a hard ferromagnetic material with a coercive field of 5.6 kOe and a specific magnetic saturation of 40 emu/g. After adding PVA to obtain the
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composite of different compositions, from 25 to 75 % wt. of PVA, the magnetic hysteresis showed a loop type wasp waist. Finally, the sample of pure PVA did not show coercivity and magnetic saturation neither.
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The wasp waist type hysteresis loops indicate that two phases or materials coexist in a same powder confirming that there is not any kind of chemical interactions between them. The > 29$: where 567 is the model used for exchange coupled of this composite is 567 :
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nanoscopic dimensions of the strontium hexaferrite phase and 29$ indicate that the estimated domain wall thickness of the polymer phase should be on the order of twice greater [30-32], the Fig. 5 shows the ordering of composite, where the diameter of particles is more lest that twice the separation between the particles this produce an abrupt fall just where the coercive field is about zero. Other effect of polymer matrix is the diminution in the magnetization saturation but this effect can be explained with the mixture theory Ms=fp*Mp+fs*Ms where fp and fs are the fraction of polyvinyl alcohol and strontium hexaferrite phases and Mp and Ms are the magnetization value of two phases. The preview 7
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formula indicate that the total saturation magnetization depending of the percentage of phases, for this reason the magnetization value of hysteresis loop decrease when the polymer percentage increase.
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The Fig. 6 shows the morphology of composites with different content of PVA. The sample of PVA (S0-P100) presents a morphology type fluted granules of large sizes of 1.2 mm, the first zoom shows an irregular surface of PVA with some flat areas for this reason we simulate a small flat area and the figure shows a wavy surface. The sample of strontium
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hexaferrite (P0-S100) shows agglomerates with bigger particle size of 27 µm, to observe small particles we select and as can be observed the agglomerates contain spherical
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particles of strontium hexaferritas, to observe the particle surface we simulate an agglomerate of two particles and as can be observed the flat surface. Three composites (P75-S25, P50-S50 and P25-S75) confirm previous model suggested because three panoramic figures shows that the PVA is matrix and there are strontium hexaferrita particles distributed in each PVA granule. The zoom of three samples shows spherical particles of different sizes as can be observe particles is separated due to polymer and the
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sizes of strontium hexaferritas agglomerate is small in comparison with sample P0-S100. Finally a particle of each composite was simulated to describe the surface as can be observed the three particles have spherical tendency as strontium hexaferrite pure sample
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but the composites have ondule surface that confirm the encapsulation of ceramic particles.
In Fig. 7 is presented the particle size distribution of pure strontium hexaferrite powder (x=0). The continue curve correspond to the volume fraction, while the dashed curve is the
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accumulate volume fraction. The obtained results indicate that 80% of particles have smaller diameter than 21 µm, and the 20% of particle volume have diameter from 21 to 40 µm. Besides, it can be observed that the average particles size is 8.6 µm, in good agreement with the data obtained by SEM.
In the SEM study we observed particles with high size because the PVA encapsulated the strontium hexaferrite particles but when we dispersed the powders in distilled water, the PVA was dissolved and the strontium hexaferrite particles was liberated so that in this 8
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study the particle size is only of strontium hexaferrite. Fig. 8 shows the effect of encapsulation add mechanical energy to form a composite in the particle size of strontium hexaferrite. As can be observed when added 25% of PVA is, the average particles size is 87 nm, but when is added 50% of PVA, the particle size increase up to 115 nm, and when is
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added 75% of PVA, the particle increase even more up to 130 nm. This behavior is similar to the evolution of the crystallite size, and these results indicate that there is an optimal ratio to decrease the crystallite and particle size. In the analyzed experimental conditions, the best ratio was 25% of polyvinyl alcohol and 75% of strontium hexaferrite, because with
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this ratio powders in scale nanometric are obtained.
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4. Conclusions.
The strontium hexaferrite was synthesized by the high-energy ball milling for 5 hours and subsequently annealing at 950°C, the crystallite and particle size were reduced by the encapsulation of SrFe12O19 with polyvinyl alcohol during high mechanical energy for 3 hours. The results of FTIR and magnetic properties indicated that the composite obtained by PVA and strontium hexaferite did not have interaction between particles and only
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coexist the particles in a same powder. The crystallite and particle measures showed a reduction in the size in all PVA-strontium hexaferrite compositions but the best relation to reduce the crystallite and particles size is 25% of PVA and 75% of strontium hexaferrite for two reasons: (a) the crystallite size is reduced from 107 nm to 40 nm, and (b) there is the
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only composition that produce particles in nonmetric scale, because we obtained particles
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of 87 nm when we dissolved the polymer in distilled water.
5. References
[1] Guerrero, A. L., Mirabal-García, M., Palomares-Sánchez, S. A., & Martínez, J. R. Effect of Pb on the magnetic interactions of the M-type hexaferrites. Journal of Magnetism and Magnetic Materials, 399 (2016) 41–45. [2] Yang, Y., Wang, F., Liu, X., Shao, J., Feng, S., Huang, D., & Li, M. The effect of Bi substitution on the microstructure and magnetic properties of the Sr0.4Ba0.3La0.3Fe12XBiXO19 hexagonal ferrites. Journal of Magnetism and Magnetic Materials, 422 (2017) 209–215.
9
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[3] Wang, H. Z., Hai, Y. N., Yao, B., Xu, Y., Shan, L., Xu, L. & Wang, Q. H. Tailoring structure and magnetic characteristics of strontium hexaferrite via Al doping engineering. Journal of Magnetism and Magnetic Materials, 422 (2017) 204-208. [4] S.S.S Afghahi, M. Jafarian, Y. Atassi. Novel approach for designing a thin and broadband microwave absorber in Ku band based on substituted M-hexaferrites Materials. Journal of Magnetism and Magnetic Materials 419 (2016) 62–67. [5] Narang, S. B., Pubby, K., Chawla, S. K., & Kaur, P. Origin of absorption peaks in reflection loss spectrum in Ku- frequency band of Co-Zr substituted strontium hexaferrites prepared using sucrose precursor. Journal of Magnetism and Magnetic Materials, 426 (2017) 202-205. [6] Abasht, B, Mohammad Mirkazemi, S. and Beitollahi, A. Solution combustion synthesis of Ca hexaferrite using glycine fuel. Journal of Alloys and Compounds, 708 (2017) 337-343. [7] Ramírez, A. E., Solarte, N. J., Singh, L. H., Coaquira, J. A., & Gaona, S. Investigation of the magnetic properties of SrFe12O19 synthesized by the Pechini and combustion methods. Journal of Magnetism and Magnetic Materials, 438 (2017) 100–106. [8] F. Sánchez-De Jesús, A.M. Bolarín-Miró, C.A. Cortés-Escobedo, R. Valenzuela, S. Ammar, Mechanosynthesis, crystal structure and magnetic characterization of M-type SrFe12O19, Ceram. Int. 40 (2014) 4033–4038. [9] F.N. Tenorio Gonzalez, A.M. Bolarín Miró, F. Sánchez De Jesús, C.A. Cortés Escobedo, S. Ammar, Mechanism and microstructural evolution of polyol mediated synthesis of nanostructured M-type SrFe12O19, J. Magn. Magn. Mater. 407 (2016) 188– 194. [10] El Briak-BenAbdeslam, H., Ginebra, M. P., Vert, M., & Boudeville, P. Wet or dry mechanochemical synthesis of calcium phosphates Influence of the water content on DCPD–CaO reaction kinetics. Acta Biomaterialia, 4 (2008) 378–386. [11] Neamţu, B. V., Chicinaş, H. F., Marinca, T. F., Isnard, O., Pană, O., & Chicinaş, I. Formation of Fe-based alloy via wet mechanical alloying assisted by PCA decomposition. Materials Chemistry and Physics, 183 (2016) 83–92. [12] Nguyen, T. P., Le, A. D., Vu, T. B., & Lam, Q. V. Investigations on Photoluminescence Enhancement of Poly(vinyl alcohol)-encapsulated Mn-doped ZnS Quantum dots. Journal of Luminescence. (2017) [13] Drmota, A, Drofenik, M. and Znidarsic, A. Synthesis and characterization of nanocrystalline strontium hexaferrite using the co-precipitation and microemulsion methods with nitrate precursors. Ceramics International, 38 (2012) 973-979. [14] Pullar, R. C. Hexagonal ferrites: A review of the synthesis, properties and applications of hexaferrite ceramics. Progress in Materials Science, 57 (2012) 1191-1334. [15] S.S.S Afghahi, M. Jafarian, Y. Atassi, C. A. Stergiou. Single and double-layer composite microwave absorbers with hexaferrite BaZn0.6Zr0.3X0.3Fe10.8O19 (X= Ti, Ce, Sn) powders. Materials Chemistry and Physics 186 (2017) 584-591. 10
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[16] Reis, E. F. D., Campos, F. S., Lage, A. P., Leite, R. C., Heneine, L. G., Vasconcelos, W. L., Mansur, H. S. (2006). Synthesis and characterization of poly (vinyl alcohol) hydrogels and hybrids for rMPB70 protein adsorption. Materials Research, 9(2), 185191. [17] Shende, P., Oza, B., & Gaud, R. S. (2018). Silver-doped titanium dioxide nanoparticles encapsulated in chitosan–PVA film for synergistic antimicrobial activity. International Journal of Polymeric Materials and Polymeric Biomaterials, 1-7. [18] Chandran, S., Ravichandran, V., Chandran, S., Chemmanda, J., & Chandarshekar, B. (2016). Biosynthesis of PVA encapsulated silver nanoparticles. Journal of applied research and technology, 14(5), 319-324. [19] Ghosh, G., Naskar, M. K., Patra, A., & Chatterjee, M. (2006). Synthesis and characterization of PVP-encapsulated ZnS nanoparticles. Optical Materials, 28(8-9), 1047-1053. [20] Rashidzadeh, A., Olad, A., Salari, D., & Jalil Hejazi, M. (2014). On the encapsulation of natural pesticide using polyvinyl alcohol/alginate–montmorillonite nanocomposite for controlled release application. Polymer Engineering & Science, 54(12), 2707-2714. [21] Tenorio-González, F. N., Bolarín-Miró, A. M., Sánchez-De Jesús, F., Vera-Serna, P., Menéndez-González, N., Sánchez-Marcos, J. Crystal structure and magnetic properties of high Mn-doped strontium hexaferrite. Journal of Alloys and Compounds. 695 (2017) 2083-2090. [22] Gražulis, S., Daškevič, A., Merkys, A., Chateigner, D., Lutterotti, L., Quiros, M. & Le Bail, A. Crystallography Open Database (COD): an open-access collection of crystal structures and platform for world-wide collaboration. Nucleic acids research, 40(D1) (2011) D420-D427. [23] Bunn, C. W. Crystal structure of polyvinyl alcohol. 161(4102) (1948) 929-930. [24] Guerrero-Serrano, A. L., Palomares-Sánchez, S. A., Mirabal-García, M., & MatutesAquino, J. A. Magneto-Structural Characterization of Strontium Substituted Lead Hexaferrite. J Supercond Nov Magn, 25 (2012) 1223–1228. [25] Stingaciu M., Topole M., McGuiness P., Christensen M. Magnetic properties of ballmilled SrFe12O19 particles consolidated by Spark-Plasma Sintering. Sci. Rep. 5 (2015)
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14112.
[26] Cheng-Ming, T, Yi-Hung, T and Shan-Hui, H. Poly(vinil alcohol) Nonocomposites reinforced with bamboo chearcol nanoparticles: mineralization bihabior and characterization. Materials research, 8 (2015) 4895-4911. [27] Abd El-Kander, K M and Orabi, A. S. Spectroscopi behabior of poly (vinyl alcohol) films with diferent molecuar weights. Polymer testing, 21 (2002) 591-595. [28] Mansur, H. S., Sadahira, C. M., Souza, A. N., & Mansur, A. A. FTIR spectroscopy characterization of poly (vinyl alcohol) hydrogel with different hydrolysis degree and chemically crosslinked with glutaraldehyde. Materials Science and Engineering C,1 28 (2008) 539– 548.
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[29] Seyyed Afghahi, S S, Jafarian, M and Atassi, Y. Microstructural and magnetic studies on BaMgxZn2xFe12-4XO19 (X=Zr,Ce,Sn) prepared via mechanical activation method to act as a microwave absorber in X-band. Journal of Magnetism and Magnetic Materials 406 (2016) 184–191. [30] Jimenez-Villacorta, F and Lewis, L. H. Advanced Permanent Magnetic Materials. Nanomagnetism (2014) 161-186. [31] Rocha, M. J. S., Theophilo, K. R. B., Denardin, J. C., Vasconcelos, I. F., Araújo, E. B., & Sombra, A. S. B. Ferrimagnetism and Ferroelectricity of the Composite Matrix: SrBi2Nb2O9 (SBN) X-BaFe12O19 (BFO) 100–X. Materials Science and Applications 3 (2012). [32] Taiping, Xie, Longjun, Xu and Chenglun, Liu. Synthesis and properties of composite magnetic material SrCoxFe12-XO19 (x=0-0.3). Powder Technology, 232 (2012).
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Table 1: Rietveld refinement of sample S100-P0.
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Figure 1: X-ray diffraction patterns of (100-x) SrFe12O19@xPVA composites with x from 0 to 100 % wt.
Figure 2: Effect of PVA on the strontium hexaferrite crystal size. Figure 3: X diffraction patterns of composites with different composition. Figure 4: VSM of composites with different composition of strontium hexaferite and PVA.
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Figure 5: Model of composite PVA with hysteresis loops type wasp waist. Figure 6: Morphology of composites with different ratio between PVA and strontium hexaferrite.
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Figure 7: Particle size distribution of pure strontium hexaferrite powder (x=0).
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Figure 8: Particle size of composite samples.
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Table 1: Rietveld refinement of sample S100-P0.
0.5881 nm
Lattice c Crystal size
2.3069 nm 117.656 nm
Parameters % Wt. Fe2O3 Lattice a=b=c
Values 6.876 % 0.5428 nm
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Values 93.124 %
Parameters % wt. SrFe12O19 Lattice a=b
R(exp)-factor
0.1218
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Microstrain 3.3264x10-7 Rwp-factor
Crystal 146.101 nm size Microstrain 1.4932x10-5 0.10958
0.8096
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SrFe12O19@PVA with different ratio were obtained by high energy ball milling using sapphire balls during 3 hours. The effect of mechanical mill in the PVA material is reported. A magnetic model of SrFe12O19@PVA wasp waist is proposed. Nanoparticles of strontium hexaferrite were obtained and liberated in water using PVA as encapsulator. The best ratio is 25% of PVA and 75% of strontium hexaferrite.
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