Understanding the Seebeck coefficient of LaNiO3 compound in the temperature range 300-620 K

TL;DR

This study investigates the thermoelectric properties of LaNiO3, including its crystal structure and Seebeck coefficient, using experimental synthesis, structural analysis, and computational modeling to understand its potential for thermoelectric applications.

Contribution

The paper combines experimental synthesis, structural analysis, and advanced DFT+U calculations to analyze the thermoelectric properties of LaNiO3 across a wide temperature range.

Findings

LaNiO3 has a trigonal crystal structure with space group R-3c.

The Seebeck coefficient is negative, indicating n-type behavior, increasing from -8 to -12 μV/K between 300K and 620K.

Computational results match experimental data when using spin-polarized DFT+U with self-interaction correction.

Abstract

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 analyze 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 trigonal structure with space group $R \, \overline{3} \, c$ (No. 167). The refined values of lattice parameters are a = b = 5.4615 \AA\, $\&$ c = 13.1777 \AA. 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 \textit{n}-type character of the compound. The value of S is found to be $\sim$ $-$8 $\mu$V/K at 300 K and at 620 K this value is $\sim$ $-$12 $\mu$V/K. The electronic structure calculation is carried out using DFT+\textit{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 + \textit{U} (= 1 eV) calculation. Based on the computational results maximum power factors are also calculated for \textit{p}-type and \textit{n}-type doping of this compound.