Room temperature thermal properties of Pb(Fe$_{1 /2}$Nb$_{1 / 2}$)O$_{3}$ ferroelectromagnetic ceramics

Abstract

The thermal properties of ferroelectromagnetic Pb(Fe$_{1 / 2}$Nb$_{1 / 2})$O$_{3}$ ceramics obtained using the conventional ceramic method at different sintering temperatures between 850$^{\circ}$C and 1000$^{\circ}$C by stoichiometric mixing of the corresponding oxides and using different kinds of precursors, have been investigated for the first time. In particular the thermal conductivity was calculated from the measured values of thermal diffusivity and specific (volume) heat capacity using the photoacoustic technique and the temperature relaxation method, respectively. Whereas no influence of the kind of precursor used for sample preparation on the thermal conductivity ($k$) was observed, we have found that the value of $k$ depends on sintering temperature and has a maximum for samples synthesized at 900$^{\circ}$C, regardless of the use of precursors or not. This paper shows that such feature is determined by the competition of the thermal conductivity mechanisms inside the grains and those at the grain boundaries in combination with the morphologic features.