Magnetic properties of the Fe2SiO4-Fe3O4 spinel solid solutions |
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| Authors: | T Yamanaka M Okita |
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| Institution: | (1) Department of Earth and Space Science Graduate School of Science, Osaka University, 1-1 Machikaneyama Toyonaka, Osaka 560-0043, Japan e-mail: 61400@center.osaka-u.ac.jp Fax/Tel.: 081-6-6850-5793, JP |
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| Abstract: | Magnetic measurement of Fe3−
x
Si
x
O4 spinel solid solutions indicates that their Curie temperatures decrease gradually, but not linearly, from 851 to 12 K with
increasing content of nonmagnetic ions Si4+. Magnetic hysteresis becomes more noticeable in solid solutions having a larger content of Fe2SiO4. Saturation magnetizations of Fe3−
x
Si
x
O4 samples increase up to x=0.357 and they are easily saturated in the field of H=0.1 T. However, magnetization of the sample of x=0.794 does not approach saturation even at high field of H=7.0 T and has a large coercive force. The Si4+ disordered distribution is confirmed to be tetrFe3+
1−
x
+
x
t
Si4+
x
(1−
t
)] octaFe2+
1+
x
Fe3+
1−
x
−
x
t
Si4+
x
t
] O4 by the spin moment, which is consistent with site occupancy obtained from X-ray crystal structure refinement. Their molecular
magnetizations would be expressed as M
B={4(1+x)+10xt}μB as functions of composition parameter x and Si4+ ordering parameter t of the solid solution. The sample of x=0.794 is antiferromagnetic below the Néel temperature, mainly due to the octahedral cation interaction M
O–M
O, while both M
T–M
O and M
O–M
O interactions induce a ferrimagnetic property. Concerning magnetic spin configuration, in the case of x>0.42, the lowest dɛ level becomes a singlet, resulting in no orbital angular momentum.
Received: 20 April 2000 / Accepted: 11 September 2000 |
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| Keywords: | Fe3 – xSixO4 spinel solid solution Saturation magnetization Magnetic hysteresis Bohr magneton Curie temperature |
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