Experimental and theoretical investigations of thermoelectric properties of La0.82Ba0.18CoO3 compound in high temperature region

Normally, understanding the temperature dependent transport properties of strongly correlated electron systems remains challenging task due to complex electronic structure and its variation (around EF) with temperature. Here, we report the applicability of DFT+U in explaining thermopower (α) and electrical conductivity (σ) in high temperature region. We have measured temperature dependent α and σ in the 300-600 K range. The non-monotonic temperature dependent behavior of α and metallic behavior of σ were observed. The value of α at 300 K was ∼15.80 μV/K which decreases upto ∼477 K (∼11.6 μV/K) and it further increases with temperature to the ∼14.8 μV/K at 600 K, whereas the values of σ were found to be ∼1.42×105Ω−1m−1 and ∼0.20×105Ω−1m−1 at 300 and 600 K, respectively. Combining the WIEN2k and BoltzTraP code, the electronic structure and temperature dependent transport coefficients were calculated. The ferromagnetic ground state electronic structure with half-metallic character obtained from the DFT+U calculations, U = 3.1 eV, provides better explanation of high-temperature transport behavior. Two current model was used for calculation of α and σ where the temperature dependent values of relaxation time (τ), almost linear for up-spin, τup, and non-linear for dn-spin, τdn, were used and estimated values were found to be in good agreement with experimentally reported values.