Synthesis, crystal structure, and thermal properties of substituted titanates Bi$_{2}$Pr$_{2}$Ti$_{3}$O$_{12}$ and Bi$_{2}$Nd$_{2}$Ti$_{3}$O$_{12}$

Titanates Bi$_{2}$Pr$_{2}$Ti$_{3}$O$_{12}$ and Bi$_{2}$Nd$_{2}$Ti$_{3}$O$_{12}$ have been obtained by the solid-phase synthesis using sequential annealing of the Bi$_{2}$O$_{3}$, Nd$_{2}$O$_{3}$, Pr$_{6}$O$_{11}$, and TiO$_{2}$ stoichiometric mixtures in air at temperatures of 1003–1323 K. Their crystal structure has been established by X-ray diffractometry and the high-temperature heat capacity has been determined by differential scanning calorimetry. Based on the experimental $C_p=f(T)$ data, the main thermodynamic functions have been calculated.