Thermophysical properties of solid solutions of $\mathrm{Bi}_{1-x}\mathrm{Nd}_x\mathrm{Fe}_{1-x}\mathrm{Mn}_x\mathrm{O}_3$ multiferroics $(x = 0.03{,}\,0.09)$ at high temperatures

The thermal diffusivity, thermal conductivity, and specific heat of solid solutions of of $\mathrm{Bi}_{1-x}\mathrm{Nd}_x\mathrm{Fe}_{1-x}\mathrm{Mn}_x\mathrm{O}_3$ multiferroics $(x = 0.03{,}\,0.09)$ have been studied in a wide temperature range (above room temperature). It is established that substitutions $\rm Nd^{3+} \to \rm Bi^{3+}$ and $\rm Mn^{3+} \to \rm Fe^{3+}$ in $\rm BiFeO_3$ lead to a decrease in the thermal diffusivity and thermal conductivity of $\mathrm{Bi}_{1-x}\mathrm{Nd}_x\mathrm{Fe}_{1-x}\mathrm{Mn}_x\mathrm{O}_3$ solid solutions and reduce the temperatures of antiferromagnetic and ferroelectric orderings. The temperature dependence of the phonon mean free path is found. The factors limiting the phonon transfer in samples are determined.