Understanding the Seebeck coefficient of LaNiO 3 compound in the temperature range 300-620 K.

Transition metal oxides have been attracted much attention in thermoelectric community from the last few decades. In the present work, we have synthesized LaNiO 3 by a simple solution combustion process. To analyse the crystal structure and structural parameters we have used Rietveld refinement method wherein FullProf software is employed. The room temperature x-ray diffraction indicates the rhombohedral structure with space groupR3¯c(No. 167). The refined values of lattice parameters are a = b = c = 5.4071 Å. Temperature dependent Seebeck coefficient ( S ) of this compound has been investigated by using experimental and computational tools. The measurement of S is conducted in the temperature range 300-620 K. The measured values of S in the entire temperature range have negative sign that indicates n-type character of the compound. The value of S is found to be ∼-8 μ V/K at 300 K and at 620 K this value is ∼-12 μ V/K. The electronic structure calculation is carried out using DFT + U method due to having strong correlation in LaNiO 3 . The calculation predicts the metallic ground state of the compound. Temperature dependent S is calculated using BoltzTraP package and compared with experiment. The best matching between experimental and calculated values of S is observed when self-interaction correction is employed as double counting correction in spin-polarized DFT + U (=1 eV) calculation. Based on the computational results maximum power factors are also calculated for p-type and n-type doping of this compound.