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We have investigated the thermal and allied properties of Tb0.5Sr0.5CoO3 for the temperature range 1K≤T≤300K using the Modified Rigid Ion Model (MRIM). The calculated bulk modulus, specific heat, and other thermodynamic properties obtained from MRIM have presented proper interpretation of the experimental data, for Sr ions doped TbCoO3 . In addition, the results on the cohesive energy (φ), Debye temperature (θD) and Gruneisen parameter (γ) are also discussed.

A single phase polycrystalline hexagonal YMn0.8Ru0.2O3 compound with space group P63cm (25-1079) have been synthesized by using solid state reaction method at sintering temperature 1280°C. The detailed low temperature electrical properties were evaluated over a broad range of temperature. The temperature dependence of the dc resistivity at low temperature reveals the semiconducting behavior and favored the variable range hopping conduction model. The obtained experimental data in the temperature range of our study can be described by the equation ρ(T) = ρ0exp[(T*/T)1/4]. The fitting results are used for the calculation of the ;temperature scale T* ~ 1.05 × 106 K and finally the density of state at Fermi level N(EF) is calculated to be ~ 5.6 × 1019 eV−1 cm−3.

The Systematic investigation of structural behaviour of GdMn1-xCrxO3 (x=0, 0.1, 0.2) has been undertaken which are synthesized by conventional solid state reaction method. All the XRD reflection lines were successfully indexed according to orthorhombic perovskite structure with space group: pbnm (62). Upon chromium (Cr) doping on the Mn site the unit cell volume has reduced due to slight difference between the ionic radii of Cr 3+ and Mn 3+ compare with Pure GdMnO 3. The relation between lattice parameter infer that all the samples have O´ type orthorhombic structure which is highly distorted perovskite structure but increasing the Cr concentration the orthorhombic distortion decrease that deduce the non John Teller nature of these samples.

We have applied the Rigid Ion Model (RIM) to study the cohesive and thermal properties of binary intermetallic BeB 2 and TiB 2. The paper reports the calculated results on cohesive energy (ϕ), compressibility (β), molecular force constant (f), Restrahalen frequency (ν0), Debye temperature (Θ D ) and Gruneisen parameter (γ) for the temperature range 50 K ≤ T ≤ 300 K and the effect of van der Waal interaction on these properties are also shown. Our results on Debye temperature are closer to the experimental data. In addition, we have computed the specific heats for BeB 2 and TiB 2 and compared them with the available experimental data.

We have investigated the cohesive and thermodynamic properties of ( KBr )1-x( KCN )x using an extended three-body force shell model (ETSM), which has been found to be adequately suitable for the description of orientationally disordered mixed cyanide-halide crystals. The specific heat of ( KBr )1-x( KCN )x for compositions (x=0.53, 0.65, 0.73, 0.84 and 0.93) at temperature 10 K ≤T≤150 K have been computed using the ETSM for the first time. The paper also reports the calculated results on Debye temperature (Θ D ), cohesive energy (Φ), compressibility (β), molecular force constant (f) and Restrahlen frequency (ν0) of ( KBr )1-x( KCN )x. The results on specific heat and some other thermal properties are in good agreement with their available experimental data.

We have investigated the elastic and thermal properties of Sr 1-x Ca x RuO 3(0≤x ≤1) perovskite using a modified rigid ion model (MRIM). The trend of variation of our computed specific heat in the temperature range 1 K ≤ T ≤ 1000 K are in good agreement with corresponding experimental data for almost all the compositions (x). The specific heat found to increase with temperature from 1 K to 300 K, while they decrease with concentration (x) for these perovskite ruthenates. Besides, we have reported the thermal properties, like thermal expansion (α), molecular force constant (f), Reststrahlen frequency (υ), cohesive energy (ϕ), Debye temperature (θD) and Gruneisen parameter (γ).

We have investigated the elastic, cohesive and thermal properties of (Lu, Sc) VO 3 and Sc 1-x Lu x VO 3(0.6 ≤ x ≤ 0.9) perovskites by means of a modified rigid ion model (MRIM). The variation of specific heat is determined following the temperature driven structural phase transitions. Also, the effect of lattice distortions on the elastic and thermal properties of the present pure and doped vanadates has been studied by an atomistic approach. The calculated bulk modulus (BT), reststrahlen frequency (ν0), cohesive energy (ϕ), Debye temperature (θD) and Gruneisen parameter (γ) reproduce well with the corresponding experimental data. The specific heat results can further be improved by including the magnetic ordering contributions to the specific heat.

Strontium doped polycrystalline YMnO 3 multiferroic ceramics prepared by using conventional solid state reaction method are examined for their structural, thermodynamic and magnetic properties. The observed pointed kinks in the specific heat study are indicative of the probable coupling between the electric and magnetic orders in this class of materials. The reported systematic specific heat studies show that the antiferromagnetic (AFM) transition temperature (TN) shifts to higher value with increasing concentration of Sr 2+ ion in the YMnO 3. The reported compounds show the independence of specific heat behavior and magnetic transition temperature with applied magnetic field of 8 T and 12 T. Our systemic magnetization studies of " Sr " doped YMnO 3 compounds indicated a weak ferromagnetic characteristic in the temperature lower than the AFM transition temperature.

We have systematically investigated the effect of phonons on elastic, thermal and cohesive properties for rare earth gallates RGaO3 (R = La, Ce, Nd, Pr, Sm, Gd) by means of a Rigid Ion Model after modifying its framework to incorporate the van der Waals interactions. Besides that, we have calculated the temperature dependence of the specific heat for the present orthogallates. The results on bulk modulus, Debye temperature and specific heat reproduce well with the available experimental data.