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Ferroelectricity
Mössbauer studies of PbFe$_{2/3}$W$_{1/3}$O$_3$ multiferroics
A. S. Kamzin,
V. A. Bokov Ioffe Institute, St. Petersburg
Abstract:
Mössbauer studies of ceramic samples of the antiferromagnetic perovskite PbFe
$_{2/3}$W
$_{1/3}$O
$_3$ have been carried out. It has been established that the temperature of transition to the magnetically ordered state is
$T_{\mathrm{N}}$ = 365 K. Iron ions in PbFe
$_{2/3}$W
$_{1/3}$O
$_3$ are found to reside in the high-spin Fe
$^{3+}$ state. The Fe
$^{3+}$ ions occupy inequivalent positions differing in the nearest cation environment, or more precisely, tungsten and iron ions are distributed in a random manner over the sites of the octahedral sublattice. The inequivalent positions arise as a result of the Fe and W ions being statistically distributed over the octahedral sublattice. For
$T >$ 0 K, magnetic fields at the nuclei and, hence, the average thermodynamic values of the magnetic moments of Fe
$^{3+}$ ions occupying inequivalent positions are different and, at a given temperature, are determined by the number of the nearest magnetic neighbors, with the effective magnetic fields
$(H_{\mathrm{eff}})$ varying differently with temperature. As the temperature is lowered, the fields
$H_{\mathrm{eff}}$ level off gradually in response to the effective magnetic fields of iron ions having different numbers of exchange bonds leveling off with decreasing temperature which lowers thermal excitation.
Received: 05.12.2012
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