Theoretical investigations of complex perovskite oxides with tetravalent cation doping at a-site to establish the role of lattice distortions

We have investigated the lattice distortions due to charge and size mismatch in complex oxides (La, Y)_1-x(Te⁴⁺, Zr⁴⁺)_xMnO₃and its effect on elastic and thermal properties of these complex perovskite manganites. The revealed data on specific heat, thermal expansion, Debye temperature and Bulk modulus studied as a function of lattice distortions using a novel atomistic approach of Atom in Molecules(AIM) theory and Modified Rigid Ion Model (MRIM) are presented for some concentrations (x) of (La, Y)_1-x(Te⁴⁺, Zr⁴⁺)_xMnO₃ in a wide temperature range. Studied compounds exhibit anomalous increase in Bulk modulus and Debye temperature with increase in doping concentration of tetravalent Te⁴⁺ and Zr⁴⁺cations at A-site. These compounds give us an unique opportunity to observe the effect of charge and size variance at A-site in perovskite structure without the effect of JT distortions due to occurrence of these compounds in Rhombohedra and hexagonal symmetry with high variance.