Synthesis, Crystal Structure, and Physicochemical Properties of Bi4–xPrxTi3O12 (x = 0.4, 0.8, 1.2, 1.6) Solid Solutions

— Bi 4– x Pr x Ti 3 O 12 ( x = 0.4, 0.8, 1.2, 1.6) solid solutions have been prepared by solid-state reactions, via multistep firing of stoichiometric mixtures of their constituent oxides in air at temperatures from 1003 to 1323 K. Their crystal structure has been determined using X-ray diffraction, and their luminescence spectra have been measured at room temperature. High-temperature heat capacity of polycrystalline substituted bismuth titanate samples has been determined by differential scanning calorimetry. The C p ( T ) curves of the solid solutions with x = 0.4 and 0.8 have extrema related to phase transitions. Experimental data have been used to calculate the main thermodynamic functions of the solid solutions.