- Email: [email protected]
Spin-glass-like behaviour in Ni2InVO6
Materials Chemistry and Physics 172 (2016) 137e142
Contents lists available at ScienceDirect
Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys
Spin-glass-like behaviour in Ni2InVO6 a a, *, E. Filipek b, A. Paczesna b, M. Oboz a, H. Duda a, A. Slebarski T. Gron , M. Fijałkowski a a b
Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007, Katowice, Poland w 42, 71-065, Szczecin, Poland Department of Inorganic and Analytical Chemistry, West Pomeranian University of Technology, Szczecin Al. Piasto
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
NiOeV2O5eIn2O3 system oxide possesses interesting technical applications. A spin-glass-like behaviour was discovered. The spin-glass state fulfils the VogelFulcher law.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 21 May 2015 Received in revised form 16 January 2016 Accepted 23 January 2016 Available online 1 February 2016
Magnetic measurements and specific heat under magnetic field showed the spin-glass-like behaviour below the freezing temperature Tf ¼ 5 K in the phase Ni2InVO6. Positive value of the paramagnetic Curie eWeiss temperature q ¼ 5.3 K suggests ferromagnetic shorterange interaction. On the other hand, the product of c0 ,T versus T reaches almost zero, decreasing continuously upon cooling, which indicates fully compensated AFM interactions between the metal centres. These effects appear to be responsible for the spin frustration. The presence of an antiferromagnetic-like correlations in Ni2InVO6 is suggested by a shift of the maxima in the specific heat C(T) or C(T)/T data toward lower temperatures when the magnetic field is increasing. Also, the freezing temperature attributed to the temperature of maximum in the ac magnetic susceptibility obeys the Vogel-Fulcher law, which is characteristic of spin-glasses. © 2016 Elsevier B.V. All rights reserved.
Keywords: Inorganic compounds Oxides Heat treatment Electron microscopy (SEM) Magnetic properties Specific heat
1. Introduction The oxides V2O5, NiO, In2O3 as well as known compounds formed with their participation i.e. InVO4, NiV2O6, Ni2V2O7 and Ni3V2O8, showing interesting physical and chemical properties, have been widely used for various technological applications, i.e. as catalysts, elements of gas sensors and storage batteries [1e6]. It is
* Corresponding author. ). E-mail address: [email protected] (T. Gron http://dx.doi.org/10.1016/j.matchemphys.2016.01.052 0254-0584/© 2016 Elsevier B.V. All rights reserved.
known that nickel vanadates(V) are the main components of the catalysts used, e.g. in the oxidation of methanol to formaldehyde [3] or in oxidative dehydrogenation reactions of ethane [4] and propane [5]. These compounds are also used in the production of electrodes for secondary lithium batteries [6]. According to literature data [7] both the InVO4 as well as its mixtures with NiO, exhibit interesting catalytic properties in water splitting reaction under visible light irradiation. The data suggest that attractive catalytic and other properties can be expected of the earlier unknown of compounds formed with participation of all components of the V2O5eNiOeIn2O3 system.
138
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
Recently, the studies of the V2O5eNiOeIn2O3 system have shown that its oxide components interact in the solid state in air, producing Ni2InVO6 [8,9]. This compound has been known since 2011 [8]. It was obtained both as a result of the reaction taking place between 2NiCO3$3Ni(OH)2$4H2O (as a precursor of NiO), V2O5 and In2O3 mixed at a molar ratio of 4:5:5 as well as in the reaction of stoichiometric mixtures NiO with InVO4 (2:1) at temperatures up to 1100 C [8,9]. So far it has been established that Ni2InVO6 is isostructural with Ni2FeVO6 and crystallises in the orthorhombic system [9]. Ni2InVO6 is stable in air up to ~1330 C and afterwards it melts incongruently with deposition of In2O3 [9]. It also known that the optical, catalytic, electrical or magnetic properties of the compound Ni2InVO6, that belongs to the family M2AVO6, where M ¼ metal(II) and A ¼ metal(III), have not been studied as yet. Literature data on some of the compounds from the family M2AVO6 such as Ni2FeVO6, Sr2FeVO6, Mg2BiVO6 and Cd2InVO6 indicate that they might be useful as components of magnetic and ferroelectric materials [10e13]. The above-mentioned applications of M2AVO6 indicate that Ni2InVO6 may show interesting among other magnetic or electric properties as opposed to Ni2FeVO6, Mg2BiVO6, Sr2FeVO6 and Cd2InVO6 as well as to diamagnetic ceramics Nb2VSbO10 [14] and Nb6VSb3O25 [15] exhibiting semiconducting properties and complex currentevoltage characteristics. Moreover, the interesting technological applications of known compounds that are formed in the binary oxides system which are the lateral limit of the ternary NiOeV2O5eIn2O3 system [3e7]. The fact that nickel is a ferromagnetic metal below the Curie temperature TC ¼ 633 K and its effective magnetic moment meff ¼ 3.2 mB [16], have motivated us to undertake the magnetic studies of Ni2InVO6 in detail. The second reason was the magnetic properties of the already known phases containing the nickel and iron ions, which suggested the appearance of the metal cluster complexes as the importance in the exchange interactions of magnetic materials [17]. Only some aspects of the magnetic properties of Ni2InVO6 have been presented earlier [18]. 2. Experimental procedure 2.1. Sample preparation The following oxides were used to synthesis of Ni2InVO6: V2O5 p.a., NiO p.a., In2O3 p.a. (all Aldrich, USA) as well as separately obtained InVO4 [7] with NiO. The compound has been obtained by heating of the mixture V2O5/NiO/In2O3 (in molar ratio 1:4:1) [8,9] according to the equation:
REFINEMENT program from the DHN/PDS package. The DTAeTGA investigation was performed using an SDT 2960 TA Instruments thermoanalyser with the air flow of 110 mL/min, at the heating rate of 10 /min. Measurements were performed in the temperature range 20e1450 C, in corundum crucibles. The mass of sample was ~20 mg. Monophase sample containing of Ni2InVO6 was also investigated by means of scanning electron microscope (SEM) (JSM-1600, Jeol, Japan).
2.2. Magnetic and specific heat measurements The dynamic ac magnetic susceptibility was measured in the zero-field cooled (ZFC) mode and in the temperature range 2-300 K. The in-phase c0 and out-of phase c00 components of the ac susceptibility were recorded at the oscillating field Hac ¼ 3.9 Oe and at the constant frequency f ¼ 300 Hz [19]. The low temperature ac magnetic susceptibility measurements were made in the frequency range 60e4000 Hz around the freezing temperature. The static dc magnetic susceptibilities were measured in two different cooling modes. In ZFC mode, the sample was first cooled down in the absence of an external magnetic field and then investigated while heating in a given magnetic field Hdc ¼ 1 kOe. The field-cooled (FC) mode usually followed the ZFC run when the same magnetic field was set on at high temperatures and the measurements were performed with a decreasing temperature. For both modes, the cooling process always started from the paramagnetic state. For these purposes a Quantum Design Physical Properties Measurement System (QD-PPMS) was used. The freezing temperature (Tf), was determined as a temperature corresponding to the extreme of dc/dT vs. T.p The ffiffiffi effective magnetic moment was calculated from the meff ¼ 2:83 C mB equation, where C is the Curie p constant ffiffiffiffiffiffiffiffiffiffi [16], and its temperature dependence from the meff ¼ 2:83 c0 ,T mB equation, where c0 is the in phase (real part) component of ac (molar) magnetic susceptibility. The exchange integral of the spin-glass system using aprandom ffiffiffiffiffiffiffiffiffiffiffiffiffi energy model [19e21] was calculated from the JSG ¼ Tf 4 ln 2 equation [20]. Magnetization isotherms were measured at 2 and 300 K using a QD-PPMS device in applied external fields up to 75 kOe. Specific heat C was measured in the temperature range 2e300 K and in the external magnetic field up to 60 kOe using a Quantum Design PPMS platform. The C(T) data were obtained for plate-like specimen with mass of 4 mg utilizing a thermal-relaxation method.
3. Results and discussion
4 NiO(s) þ V2O5(s) þ In2O3(s) ¼ 2 Ni2InVO6(s)
3.1. Characteristic of Ni2InVO6
The compound Ni2InVO6 was also obtained by heating the mixture of InVO4 and NiO (in molar ratio 1:2) [9]:
Fig. 1 shows a fragment of diffraction pattern (XRD) of compound Ni2InVO6 obtained in the context of this paper, which is almost identical to that shown in Ref. [9]. The powder diffraction pattern obtained in this work of Ni2InVO6 was indexed in order to verify the system in which the known since recently compound crystallizes and to determine parameters of the unit cell. The results of indexing confirmed that Ni2InVO6 crystallizes in the orthorhombic system (cell of C type) with the following unit cell parameters: a ¼ 17.521(2) Å, b ¼ 8.470(1) Å, c ¼ 6.062(1) Å. The unit cell volume V ¼ 899.6 Å3; the number of the stoichiometric units in the unit cell Z ¼ 8 [9]. The result of DTAeTGA measurement of Ni2InVO6 additionally confirmed that the phase is stable in air up to ~1330 ± 10 C [8,9]. The crystals of Ni2InVO6 visible in Fig. 2, differ slightly in the sizes from the crystals of the compound obtained in Ref. [9]. The sizes of larger crystals are of the order of 8 mm whereas the size of smaller crystals does not exceed 1 mm.
InVO4(s) þ 2 NiO(s) ¼ Ni2InVO6(s) According to the procedure of synthesis described in Ref. [9] the reacting substances mixed at appropriate proportions were homogenised by grinding, shaped into pellets and were then heated in 24-h stages in air in the temperature range from 500 to 1100 C. After each heating stage, the phases in the samples were identified by powder diffraction patterns of the samples recorded on a diffractometer Philips PW1710 (Alabama, USA) using the CoKa radiation and Fe filter. The powder diffraction pattern of Ni2InVO6 obtained was indexed with the aid of the programs POWDER and the parameters of selected unit cell were refined using the
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
139
Fig. 1. Fragment of X-ray diffraction pattern of Ni2InVO6: d/Å (hkl). Fig. 3. In phase c0 and out of phase c0 0 components of ac magnetic susceptibility as well as 1/c0 vs. temperature T recorded at internal oscillating magnetic field Hac ¼ 3.9 Oe with internal frequency f ¼ 300 Hz. The solid (black) line, (Teq)/C, indicates a CurieeWeiss behaviour and q is the paramagnetic CurieeWeiss temperature. The solid (blue) line is for an estimation of the Lande factor from the Curie constant C. The inset shows the enlargement of out of phase c0 0 components of ac magnetic susceptibility. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 2. SEM image of Ni2InVO6.
3.2. Magnetic properties The results of magnetic measurements of Ni2InVO6 are shown in Figs. 3e6 and in Table 1. The temperature dependence of the in phase c0 (T) (real part) components of ac magnetic susceptibility (Fig. 3) shows a maximum at 5 K characteristic for the antiferromagnetic (AFM) order. This behaviour can also be seen on the dependence c0 ,T versus T (Fig. 4), the product of c0 ,T reaches zero, decreasing continuously upon cooling, which indicates fully compensated AFM interactions between the metal centres. However, the out-of-phase c00 (T) (imaginary part) component of ac susceptibility (Fig. 3 and the inset) shows an absence of the energy loss, necessary, for example, for an optional magnetic-domain-wall motion or for rotation of magnetization within domains, suggesting the spin-frustration. On the other hand, positive value of the paramagnetic CurieeWeiss temperature q ¼ 5.3 K suggests ferromagnetic (FM) shorterange interaction (Table 1). Thus, the competition between AFM and FM interactions appears to be responsible for the spin frustration. The shape of the magnetization isotherm at 2 K (Fig. 5) shows that the sample is difficult to be magnetized and does not reach
Fig. 4. Product c0 ,T and effective magnetic moment meff vs. temperature T.
saturation even at 75 kOe. This may be caused by anisotropy of spineorbit coupling evident in the high value of the effective magnetic moment (meff ¼ 5.058 mB/f.u.) close the effective number of Bohr magnetons (peff ¼ 5.590) (see Table 1 and Fig. 4). This provides a high orbital contribution to the magnetic moment. Also, factor gc ¼ 1.13 (Table 1), well below 2, a small value of the Lande estimated from the Curie constant (Fig. 3) shows that magnetic moment derives not only from the spin. Fig. 5 also shows that the
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
140
the geometrical spin frustration. The calculated value of the exchange integral JSG ¼ 6.93 from a random energy model [20e22] is typical for geometrical frustration because in the case of competitive exchange interactions JSG is three times larger, as observed for tin doped ZnCr2Se4 single crystals [23]. 3.3. Specific heat studies In Fig. 7 is shown that the zero-field heat capacity C(T) has not lshaped anomaly, the C(T)/T at H ¼ 0 has a sharp peak with a maximum at ~5 K in agreement with the susceptibility data. With increasing magnetic field the specific heat capacity C(T) (Fig. 8) demonstrates only noticeable change of inclination on the curve C(T) at the transition temperature of 5 K. The inset of Fig. 8 shows that the maximum of the derivative of specific heat, dC/dT, with increasing magnetic field shifts slightly toward lower temperatures. This behaviour is characteristic of the antiferromagnetic order. That's why we decided to investigate this behaviour in more detail. Firstly, the low-temperature specific heat, C(T)/T, in several magnetic fields was measured (Fig. 9). With rising magnetic field the maximum in C(T)/T shifts toward lower temperatures which suggests antiferromagnetic correlations or antiferromagnetic-type spin-glass behaviour. Secondly, the dynamic ac susceptibility as a function of frequency around the transition temperature was measured. Fig. 10 shows the frequency dependence of the real (c0 ) and imaginary (c00 ) part of the magnetic susceptibility. Both components exhibit the maxima at ~5 K with the value and temperature of the maximum depending on the frequency and an applied magnetic field. The temperature of the maximum of c0 could be attributed to a spin-glass transition at Tf. We found that the frequency n dependence of Tf follows the Vogel-Fulcher law (c.f. Fig. 11) characteristic of spin-glass behaviour [24]. In Fig. 11 Tf is linear vs. 1/ln(n0/n), considering a typical value of n0 ¼ 1013 Hz [25].
Fig. 5. Magnetization M vs. magnetic field H at 2 and 300 K.
4. Conclusions In conclusion, we have demonstrated Ni2InVO6 phase showing the spin-glass-like state below the freezing temperatures Tf ¼ 5 K. This state was additionally confirmed by the specific heat studies and the Vogel-Fulcher law. The weak short-range ferromagnetic interactions, represented by the positive value of q ¼ 5.3 K, correlates well with the exchange integral JSG ¼ 6.93. Slightly smaller
Fig. 6. ZFC and FC dc magnetic susceptibility c vs. temperature T at Hdc ¼ 1 kOe. The inset shows the enlargement of ZFC-FC splitting. Tf indicated by arrow is the freezing temperature.
Table 1 Magnetic parameters of Ni2InVO6: C is the Curie constant, q is the CurieeWeiss temperature, Tf is the freezing temperature, meff is the effective magnetic moment, factor estimated from peff is the effective number of Bohr magetons, gc is the Lande the Curie constant and JSG is the exchange integral of the spin-glass system. Compound
C (emu,K/mol)
q (K) Tf (K) meff (mB/f.u.) peff
gc
JSG (K)
Ni2InVO6
3.194
5.3
1.13
6.93
5.0
5.058
5.590
shape of the magnetic isotherms at 300 K is linear, typical for the paramagnetic response to the magnetic field. The splitting of the ZFCeFC dc magnetic susceptibility visible in Fig. 6 and in the inset is characteristic for the spin-glass state. This state can be due to AFM-FM competition effects and also come from
Fig. 7. Temperature dependence of the specific heat plotted as C and C/T vs. T in zero magnetic field.
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
Fig. 8. Specific heat, C, vs. temperature T (limited to 20 K) taken at different external magnetic fields. The inset shows a derivative of the specific heat dC/dT vs. temperature T.
Fig. 9. Temperature dependence of the specific heat plotted as C/T vs. T (limited to 20 K) at different external magnetic fields. Tf indicated by arrow is the freezing temperature.
Fig. 10. Ac magnetic susceptibility cac vs. temperature T recorded at different frequencies. In phase and out of phase components of ac magnetic susceptibility are described by c0 and c0 0 , respectively. c0 0 is enlarged 40 times for better presentation.
Fig. 11. Freezing temperature, Tf, vs. the inverse of the logarithm of the relative frequency, 1/ln(n0/n), where n0 ¼ 1013 Hz [24]. The solid (black) line is a linear fit.
References
effective magnetic moment in comparison with the effective number of Bohr magnetons indicate the spineorbit coupling in Ni2InVO6.
[1] [2] [3] [4]
Acknowledgements
[5] [6] [7] [8]
This work was partly supported by Ministry of Scientific Research and Information Technology (Poland) and funded from and MF thank the science resources: No. 1S-0300-500-1-05-06. AS National Science Centre (NCN) for financial support, on the basis of Decision No. DEC-2012/07/B/ST3/03027.
141
[9] [10]
[11]
Yu Dobrovolsky, L. Leonova, S. Nadkhina, Ionics 1 (1995) 228e234. X. Niu, H. Zhong, X. Wang, K. Jiang, Sens. Actuators B 115 (2006) 434e438. ski, J. Gallus-Olender, React. Kinet. Catal. Lett. 11 (1979) 377e381. R. Malin s Corbera n, E.A. Mamedov, Catal. Lett. 40 R.X. Valenzuela, J.L.G. Fierro, V. Corte (1996) 223e228. B. Zhaorigetu, W. Li, H. Xu, R. Kieffer, Catal. Lett. 94 (2004) 125e129. E. Andrukaitis, J.P. Cooper, J.H. Smit, J. Power Sources 54 (1995) 465e469. H.-Y. Lin, Y.-F. Chen, Y.-W. Chen Int, J. Hydrog. Energy 32 (2007) 86e92. E. Filipek, A. Paczesna, Polish Patent No. P396804, Warsaw, 2014 (Patent Application 2011). A. Paczesna, E. Filipek, Thermochim. Acta 618 (2015) 67e73. N. Guskos, V. Likodimos, S. Los, W. Kempinski, J. Stankowski, M. Wabia, J. Typek, A. Blonska-Tabero, P. Tabero, I. Rychlowska-Himmel, Phys. B 284e288 (2000) 1456e1458. A. Maryanowska, J. Pietrzak, W. Zarek, J. Magn. Magn. Mater 140e144 (1995) 1581e1582.
142
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
[12] I. Radosavljevic, J.S.O. Evans, A.W. Sleight, J. Solid State Chem. 137 (1998) 143e147. [13] T. Yang, J. Sun, J. Yeon, P. Shiv Halasyamani, S. Huang, J. Hemberger, M. Greenblatt, Chem. Mater 22 (2010) 4814e4820. , E. Filipek, M. Piz, H. Duda, T. Mydlarz, Mater. Res. Bull. 48 (2013) [14] T. Gron 2712e2714. , E. Filipek, M. Piz, H. Duda, Mater. Res. Bull. 51 (2014) 105e108. [15] T. Gron [16] A.H. Morrish, Physical Principles of Magnetism, John Wiley & Sons, Inc., New York, 1965. [17] N. Guskos, M. Wabia, V. Likodimos, J. Typek, M. Kurzawa, A. Blonska-Tabero, I. Rychlowska-Himmel, Mol. Phys. Rep. 36 (2002) 27e36. , E. Filipek, A. Paczesna, M. Oboz, H. Duda, Spin-glass-like Behaviour in [18] T. Gron Polycrystalline Ni2InVO6, SCTE 2014-19th International Conference on Solid
[19] [20] [21] [22] [23]
Compounds of Transition Elements, 21-26, Italy, Book of Abstracts, Genova, June 2014, p. 143. _ , S. Mazur, A.W. Pacyna, A. Waskowska, H. Duda, E. Macia˛ zek, T. Gron T. Mydlarz, A. Gilewski, Phys. Rev. B 77 (2008) 035207. B. Derrida, Phys. Rev. Lett. 45 (1980) 79e82. B. Derrida, Phys. Rev. B 24 (1981) 2613e2626. K. Binder, A.P. Young, Rev. Mod. Phys. 58 (1986) 801e976. _ , J. Kusz, M. Zelechower, _ I. Jendrzejewska, T. Gron E. Macia˛ zek, A. Slebarski,
M. Fijałkowski, J. Alloys Comp. 635 (2015) 238e244. [24] J.A. Mydosh, Spin Glasses: An Experimental Introduction, Taylor and Francis, London, 1993, p. 64. [25] J.L. Tholence, Solid State Commun. 35 (1980) 113e117.
Contents lists available at ScienceDirect
Materials Chemistry and Physics journal homepage: www.elsevier.com/locate/matchemphys
Spin-glass-like behaviour in Ni2InVO6 a a, *, E. Filipek b, A. Paczesna b, M. Oboz a, H. Duda a, A. Slebarski T. Gron , M. Fijałkowski a a b
Institute of Physics, University of Silesia, ul. Uniwersytecka 4, 40-007, Katowice, Poland w 42, 71-065, Szczecin, Poland Department of Inorganic and Analytical Chemistry, West Pomeranian University of Technology, Szczecin Al. Piasto
h i g h l i g h t s
g r a p h i c a l a b s t r a c t
NiOeV2O5eIn2O3 system oxide possesses interesting technical applications. A spin-glass-like behaviour was discovered. The spin-glass state fulfils the VogelFulcher law.
a r t i c l e i n f o
a b s t r a c t
Article history: Received 21 May 2015 Received in revised form 16 January 2016 Accepted 23 January 2016 Available online 1 February 2016
Magnetic measurements and specific heat under magnetic field showed the spin-glass-like behaviour below the freezing temperature Tf ¼ 5 K in the phase Ni2InVO6. Positive value of the paramagnetic Curie eWeiss temperature q ¼ 5.3 K suggests ferromagnetic shorterange interaction. On the other hand, the product of c0 ,T versus T reaches almost zero, decreasing continuously upon cooling, which indicates fully compensated AFM interactions between the metal centres. These effects appear to be responsible for the spin frustration. The presence of an antiferromagnetic-like correlations in Ni2InVO6 is suggested by a shift of the maxima in the specific heat C(T) or C(T)/T data toward lower temperatures when the magnetic field is increasing. Also, the freezing temperature attributed to the temperature of maximum in the ac magnetic susceptibility obeys the Vogel-Fulcher law, which is characteristic of spin-glasses. © 2016 Elsevier B.V. All rights reserved.
Keywords: Inorganic compounds Oxides Heat treatment Electron microscopy (SEM) Magnetic properties Specific heat
1. Introduction The oxides V2O5, NiO, In2O3 as well as known compounds formed with their participation i.e. InVO4, NiV2O6, Ni2V2O7 and Ni3V2O8, showing interesting physical and chemical properties, have been widely used for various technological applications, i.e. as catalysts, elements of gas sensors and storage batteries [1e6]. It is
* Corresponding author. ). E-mail address: [email protected] (T. Gron http://dx.doi.org/10.1016/j.matchemphys.2016.01.052 0254-0584/© 2016 Elsevier B.V. All rights reserved.
known that nickel vanadates(V) are the main components of the catalysts used, e.g. in the oxidation of methanol to formaldehyde [3] or in oxidative dehydrogenation reactions of ethane [4] and propane [5]. These compounds are also used in the production of electrodes for secondary lithium batteries [6]. According to literature data [7] both the InVO4 as well as its mixtures with NiO, exhibit interesting catalytic properties in water splitting reaction under visible light irradiation. The data suggest that attractive catalytic and other properties can be expected of the earlier unknown of compounds formed with participation of all components of the V2O5eNiOeIn2O3 system.
138
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
Recently, the studies of the V2O5eNiOeIn2O3 system have shown that its oxide components interact in the solid state in air, producing Ni2InVO6 [8,9]. This compound has been known since 2011 [8]. It was obtained both as a result of the reaction taking place between 2NiCO3$3Ni(OH)2$4H2O (as a precursor of NiO), V2O5 and In2O3 mixed at a molar ratio of 4:5:5 as well as in the reaction of stoichiometric mixtures NiO with InVO4 (2:1) at temperatures up to 1100 C [8,9]. So far it has been established that Ni2InVO6 is isostructural with Ni2FeVO6 and crystallises in the orthorhombic system [9]. Ni2InVO6 is stable in air up to ~1330 C and afterwards it melts incongruently with deposition of In2O3 [9]. It also known that the optical, catalytic, electrical or magnetic properties of the compound Ni2InVO6, that belongs to the family M2AVO6, where M ¼ metal(II) and A ¼ metal(III), have not been studied as yet. Literature data on some of the compounds from the family M2AVO6 such as Ni2FeVO6, Sr2FeVO6, Mg2BiVO6 and Cd2InVO6 indicate that they might be useful as components of magnetic and ferroelectric materials [10e13]. The above-mentioned applications of M2AVO6 indicate that Ni2InVO6 may show interesting among other magnetic or electric properties as opposed to Ni2FeVO6, Mg2BiVO6, Sr2FeVO6 and Cd2InVO6 as well as to diamagnetic ceramics Nb2VSbO10 [14] and Nb6VSb3O25 [15] exhibiting semiconducting properties and complex currentevoltage characteristics. Moreover, the interesting technological applications of known compounds that are formed in the binary oxides system which are the lateral limit of the ternary NiOeV2O5eIn2O3 system [3e7]. The fact that nickel is a ferromagnetic metal below the Curie temperature TC ¼ 633 K and its effective magnetic moment meff ¼ 3.2 mB [16], have motivated us to undertake the magnetic studies of Ni2InVO6 in detail. The second reason was the magnetic properties of the already known phases containing the nickel and iron ions, which suggested the appearance of the metal cluster complexes as the importance in the exchange interactions of magnetic materials [17]. Only some aspects of the magnetic properties of Ni2InVO6 have been presented earlier [18]. 2. Experimental procedure 2.1. Sample preparation The following oxides were used to synthesis of Ni2InVO6: V2O5 p.a., NiO p.a., In2O3 p.a. (all Aldrich, USA) as well as separately obtained InVO4 [7] with NiO. The compound has been obtained by heating of the mixture V2O5/NiO/In2O3 (in molar ratio 1:4:1) [8,9] according to the equation:
REFINEMENT program from the DHN/PDS package. The DTAeTGA investigation was performed using an SDT 2960 TA Instruments thermoanalyser with the air flow of 110 mL/min, at the heating rate of 10 /min. Measurements were performed in the temperature range 20e1450 C, in corundum crucibles. The mass of sample was ~20 mg. Monophase sample containing of Ni2InVO6 was also investigated by means of scanning electron microscope (SEM) (JSM-1600, Jeol, Japan).
2.2. Magnetic and specific heat measurements The dynamic ac magnetic susceptibility was measured in the zero-field cooled (ZFC) mode and in the temperature range 2-300 K. The in-phase c0 and out-of phase c00 components of the ac susceptibility were recorded at the oscillating field Hac ¼ 3.9 Oe and at the constant frequency f ¼ 300 Hz [19]. The low temperature ac magnetic susceptibility measurements were made in the frequency range 60e4000 Hz around the freezing temperature. The static dc magnetic susceptibilities were measured in two different cooling modes. In ZFC mode, the sample was first cooled down in the absence of an external magnetic field and then investigated while heating in a given magnetic field Hdc ¼ 1 kOe. The field-cooled (FC) mode usually followed the ZFC run when the same magnetic field was set on at high temperatures and the measurements were performed with a decreasing temperature. For both modes, the cooling process always started from the paramagnetic state. For these purposes a Quantum Design Physical Properties Measurement System (QD-PPMS) was used. The freezing temperature (Tf), was determined as a temperature corresponding to the extreme of dc/dT vs. T.p The ffiffiffi effective magnetic moment was calculated from the meff ¼ 2:83 C mB equation, where C is the Curie p constant ffiffiffiffiffiffiffiffiffiffi [16], and its temperature dependence from the meff ¼ 2:83 c0 ,T mB equation, where c0 is the in phase (real part) component of ac (molar) magnetic susceptibility. The exchange integral of the spin-glass system using aprandom ffiffiffiffiffiffiffiffiffiffiffiffiffi energy model [19e21] was calculated from the JSG ¼ Tf 4 ln 2 equation [20]. Magnetization isotherms were measured at 2 and 300 K using a QD-PPMS device in applied external fields up to 75 kOe. Specific heat C was measured in the temperature range 2e300 K and in the external magnetic field up to 60 kOe using a Quantum Design PPMS platform. The C(T) data were obtained for plate-like specimen with mass of 4 mg utilizing a thermal-relaxation method.
3. Results and discussion
4 NiO(s) þ V2O5(s) þ In2O3(s) ¼ 2 Ni2InVO6(s)
3.1. Characteristic of Ni2InVO6
The compound Ni2InVO6 was also obtained by heating the mixture of InVO4 and NiO (in molar ratio 1:2) [9]:
Fig. 1 shows a fragment of diffraction pattern (XRD) of compound Ni2InVO6 obtained in the context of this paper, which is almost identical to that shown in Ref. [9]. The powder diffraction pattern obtained in this work of Ni2InVO6 was indexed in order to verify the system in which the known since recently compound crystallizes and to determine parameters of the unit cell. The results of indexing confirmed that Ni2InVO6 crystallizes in the orthorhombic system (cell of C type) with the following unit cell parameters: a ¼ 17.521(2) Å, b ¼ 8.470(1) Å, c ¼ 6.062(1) Å. The unit cell volume V ¼ 899.6 Å3; the number of the stoichiometric units in the unit cell Z ¼ 8 [9]. The result of DTAeTGA measurement of Ni2InVO6 additionally confirmed that the phase is stable in air up to ~1330 ± 10 C [8,9]. The crystals of Ni2InVO6 visible in Fig. 2, differ slightly in the sizes from the crystals of the compound obtained in Ref. [9]. The sizes of larger crystals are of the order of 8 mm whereas the size of smaller crystals does not exceed 1 mm.
InVO4(s) þ 2 NiO(s) ¼ Ni2InVO6(s) According to the procedure of synthesis described in Ref. [9] the reacting substances mixed at appropriate proportions were homogenised by grinding, shaped into pellets and were then heated in 24-h stages in air in the temperature range from 500 to 1100 C. After each heating stage, the phases in the samples were identified by powder diffraction patterns of the samples recorded on a diffractometer Philips PW1710 (Alabama, USA) using the CoKa radiation and Fe filter. The powder diffraction pattern of Ni2InVO6 obtained was indexed with the aid of the programs POWDER and the parameters of selected unit cell were refined using the
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
139
Fig. 1. Fragment of X-ray diffraction pattern of Ni2InVO6: d/Å (hkl). Fig. 3. In phase c0 and out of phase c0 0 components of ac magnetic susceptibility as well as 1/c0 vs. temperature T recorded at internal oscillating magnetic field Hac ¼ 3.9 Oe with internal frequency f ¼ 300 Hz. The solid (black) line, (Teq)/C, indicates a CurieeWeiss behaviour and q is the paramagnetic CurieeWeiss temperature. The solid (blue) line is for an estimation of the Lande factor from the Curie constant C. The inset shows the enlargement of out of phase c0 0 components of ac magnetic susceptibility. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
Fig. 2. SEM image of Ni2InVO6.
3.2. Magnetic properties The results of magnetic measurements of Ni2InVO6 are shown in Figs. 3e6 and in Table 1. The temperature dependence of the in phase c0 (T) (real part) components of ac magnetic susceptibility (Fig. 3) shows a maximum at 5 K characteristic for the antiferromagnetic (AFM) order. This behaviour can also be seen on the dependence c0 ,T versus T (Fig. 4), the product of c0 ,T reaches zero, decreasing continuously upon cooling, which indicates fully compensated AFM interactions between the metal centres. However, the out-of-phase c00 (T) (imaginary part) component of ac susceptibility (Fig. 3 and the inset) shows an absence of the energy loss, necessary, for example, for an optional magnetic-domain-wall motion or for rotation of magnetization within domains, suggesting the spin-frustration. On the other hand, positive value of the paramagnetic CurieeWeiss temperature q ¼ 5.3 K suggests ferromagnetic (FM) shorterange interaction (Table 1). Thus, the competition between AFM and FM interactions appears to be responsible for the spin frustration. The shape of the magnetization isotherm at 2 K (Fig. 5) shows that the sample is difficult to be magnetized and does not reach
Fig. 4. Product c0 ,T and effective magnetic moment meff vs. temperature T.
saturation even at 75 kOe. This may be caused by anisotropy of spineorbit coupling evident in the high value of the effective magnetic moment (meff ¼ 5.058 mB/f.u.) close the effective number of Bohr magnetons (peff ¼ 5.590) (see Table 1 and Fig. 4). This provides a high orbital contribution to the magnetic moment. Also, factor gc ¼ 1.13 (Table 1), well below 2, a small value of the Lande estimated from the Curie constant (Fig. 3) shows that magnetic moment derives not only from the spin. Fig. 5 also shows that the
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
140
the geometrical spin frustration. The calculated value of the exchange integral JSG ¼ 6.93 from a random energy model [20e22] is typical for geometrical frustration because in the case of competitive exchange interactions JSG is three times larger, as observed for tin doped ZnCr2Se4 single crystals [23]. 3.3. Specific heat studies In Fig. 7 is shown that the zero-field heat capacity C(T) has not lshaped anomaly, the C(T)/T at H ¼ 0 has a sharp peak with a maximum at ~5 K in agreement with the susceptibility data. With increasing magnetic field the specific heat capacity C(T) (Fig. 8) demonstrates only noticeable change of inclination on the curve C(T) at the transition temperature of 5 K. The inset of Fig. 8 shows that the maximum of the derivative of specific heat, dC/dT, with increasing magnetic field shifts slightly toward lower temperatures. This behaviour is characteristic of the antiferromagnetic order. That's why we decided to investigate this behaviour in more detail. Firstly, the low-temperature specific heat, C(T)/T, in several magnetic fields was measured (Fig. 9). With rising magnetic field the maximum in C(T)/T shifts toward lower temperatures which suggests antiferromagnetic correlations or antiferromagnetic-type spin-glass behaviour. Secondly, the dynamic ac susceptibility as a function of frequency around the transition temperature was measured. Fig. 10 shows the frequency dependence of the real (c0 ) and imaginary (c00 ) part of the magnetic susceptibility. Both components exhibit the maxima at ~5 K with the value and temperature of the maximum depending on the frequency and an applied magnetic field. The temperature of the maximum of c0 could be attributed to a spin-glass transition at Tf. We found that the frequency n dependence of Tf follows the Vogel-Fulcher law (c.f. Fig. 11) characteristic of spin-glass behaviour [24]. In Fig. 11 Tf is linear vs. 1/ln(n0/n), considering a typical value of n0 ¼ 1013 Hz [25].
Fig. 5. Magnetization M vs. magnetic field H at 2 and 300 K.
4. Conclusions In conclusion, we have demonstrated Ni2InVO6 phase showing the spin-glass-like state below the freezing temperatures Tf ¼ 5 K. This state was additionally confirmed by the specific heat studies and the Vogel-Fulcher law. The weak short-range ferromagnetic interactions, represented by the positive value of q ¼ 5.3 K, correlates well with the exchange integral JSG ¼ 6.93. Slightly smaller
Fig. 6. ZFC and FC dc magnetic susceptibility c vs. temperature T at Hdc ¼ 1 kOe. The inset shows the enlargement of ZFC-FC splitting. Tf indicated by arrow is the freezing temperature.
Table 1 Magnetic parameters of Ni2InVO6: C is the Curie constant, q is the CurieeWeiss temperature, Tf is the freezing temperature, meff is the effective magnetic moment, factor estimated from peff is the effective number of Bohr magetons, gc is the Lande the Curie constant and JSG is the exchange integral of the spin-glass system. Compound
C (emu,K/mol)
q (K) Tf (K) meff (mB/f.u.) peff
gc
JSG (K)
Ni2InVO6
3.194
5.3
1.13
6.93
5.0
5.058
5.590
shape of the magnetic isotherms at 300 K is linear, typical for the paramagnetic response to the magnetic field. The splitting of the ZFCeFC dc magnetic susceptibility visible in Fig. 6 and in the inset is characteristic for the spin-glass state. This state can be due to AFM-FM competition effects and also come from
Fig. 7. Temperature dependence of the specific heat plotted as C and C/T vs. T in zero magnetic field.
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
Fig. 8. Specific heat, C, vs. temperature T (limited to 20 K) taken at different external magnetic fields. The inset shows a derivative of the specific heat dC/dT vs. temperature T.
Fig. 9. Temperature dependence of the specific heat plotted as C/T vs. T (limited to 20 K) at different external magnetic fields. Tf indicated by arrow is the freezing temperature.
Fig. 10. Ac magnetic susceptibility cac vs. temperature T recorded at different frequencies. In phase and out of phase components of ac magnetic susceptibility are described by c0 and c0 0 , respectively. c0 0 is enlarged 40 times for better presentation.
Fig. 11. Freezing temperature, Tf, vs. the inverse of the logarithm of the relative frequency, 1/ln(n0/n), where n0 ¼ 1013 Hz [24]. The solid (black) line is a linear fit.
References
effective magnetic moment in comparison with the effective number of Bohr magnetons indicate the spineorbit coupling in Ni2InVO6.
[1] [2] [3] [4]
Acknowledgements
[5] [6] [7] [8]
This work was partly supported by Ministry of Scientific Research and Information Technology (Poland) and funded from and MF thank the science resources: No. 1S-0300-500-1-05-06. AS National Science Centre (NCN) for financial support, on the basis of Decision No. DEC-2012/07/B/ST3/03027.
141
[9] [10]
[11]
Yu Dobrovolsky, L. Leonova, S. Nadkhina, Ionics 1 (1995) 228e234. X. Niu, H. Zhong, X. Wang, K. Jiang, Sens. Actuators B 115 (2006) 434e438. ski, J. Gallus-Olender, React. Kinet. Catal. Lett. 11 (1979) 377e381. R. Malin s Corbera n, E.A. Mamedov, Catal. Lett. 40 R.X. Valenzuela, J.L.G. Fierro, V. Corte (1996) 223e228. B. Zhaorigetu, W. Li, H. Xu, R. Kieffer, Catal. Lett. 94 (2004) 125e129. E. Andrukaitis, J.P. Cooper, J.H. Smit, J. Power Sources 54 (1995) 465e469. H.-Y. Lin, Y.-F. Chen, Y.-W. Chen Int, J. Hydrog. Energy 32 (2007) 86e92. E. Filipek, A. Paczesna, Polish Patent No. P396804, Warsaw, 2014 (Patent Application 2011). A. Paczesna, E. Filipek, Thermochim. Acta 618 (2015) 67e73. N. Guskos, V. Likodimos, S. Los, W. Kempinski, J. Stankowski, M. Wabia, J. Typek, A. Blonska-Tabero, P. Tabero, I. Rychlowska-Himmel, Phys. B 284e288 (2000) 1456e1458. A. Maryanowska, J. Pietrzak, W. Zarek, J. Magn. Magn. Mater 140e144 (1995) 1581e1582.
142
et al. / Materials Chemistry and Physics 172 (2016) 137e142 T. Gron
[12] I. Radosavljevic, J.S.O. Evans, A.W. Sleight, J. Solid State Chem. 137 (1998) 143e147. [13] T. Yang, J. Sun, J. Yeon, P. Shiv Halasyamani, S. Huang, J. Hemberger, M. Greenblatt, Chem. Mater 22 (2010) 4814e4820. , E. Filipek, M. Piz, H. Duda, T. Mydlarz, Mater. Res. Bull. 48 (2013) [14] T. Gron 2712e2714. , E. Filipek, M. Piz, H. Duda, Mater. Res. Bull. 51 (2014) 105e108. [15] T. Gron [16] A.H. Morrish, Physical Principles of Magnetism, John Wiley & Sons, Inc., New York, 1965. [17] N. Guskos, M. Wabia, V. Likodimos, J. Typek, M. Kurzawa, A. Blonska-Tabero, I. Rychlowska-Himmel, Mol. Phys. Rep. 36 (2002) 27e36. , E. Filipek, A. Paczesna, M. Oboz, H. Duda, Spin-glass-like Behaviour in [18] T. Gron Polycrystalline Ni2InVO6, SCTE 2014-19th International Conference on Solid
[19] [20] [21] [22] [23]
Compounds of Transition Elements, 21-26, Italy, Book of Abstracts, Genova, June 2014, p. 143. _ , S. Mazur, A.W. Pacyna, A. Waskowska, H. Duda, E. Macia˛ zek, T. Gron T. Mydlarz, A. Gilewski, Phys. Rev. B 77 (2008) 035207. B. Derrida, Phys. Rev. Lett. 45 (1980) 79e82. B. Derrida, Phys. Rev. B 24 (1981) 2613e2626. K. Binder, A.P. Young, Rev. Mod. Phys. 58 (1986) 801e976. _ , J. Kusz, M. Zelechower, _ I. Jendrzejewska, T. Gron E. Macia˛ zek, A. Slebarski,
M. Fijałkowski, J. Alloys Comp. 635 (2015) 238e244. [24] J.A. Mydosh, Spin Glasses: An Experimental Introduction, Taylor and Francis, London, 1993, p. 64. [25] J.L. Tholence, Solid State Commun. 35 (1980) 113e117.