Effect of Sodium Doping on Thermal Properties of Perovskite RMnO3 for Potential Magnetoelectric Applications

Abstract

The partial replacement of rare earth cation by sodium introduces large size and charge mismatch at A-site affecting the bulk modulus and thermal properties of RMnO₃ which in turn makes them suitable candidates for thermoelectric applications. Thermal, elastic, cohesive properties of sodium doped Rare Earth manganites R_1-xNa_xMnO₃ (R³⁺= La, Pr, Tb) has been studied by means of a Modified Rigid Ion Model (MRIM) and AIM theory. Lattice specific heat (C_p) of Pr_0.8Na_0.2MnO₃, and Tb_0.85Na_0.15MnO₃ as a function of temperature (1K£T£ 350K) is found to be in agreement with the published data. The trend of variation of Debye temperature (?_D), thermal expansion (?), bulk modulus (B) and cohesive energy (?) with A-site cationic radius is predicted probably for the first time for these technologically important doped rare earth manganites.

Keywords: Thermal Expansion, Specific Heat, Thermal properties, Colossal Magnetoresistance Materials, Magnetoelectric materials.