Assessing Temperature Dependence of Band Gap Renormalization in LaCrO_3−δ via First-Principles and Experimental Corroboration

For applications in combustion environments, understanding the temperature dependence of functional properties in high-temperature gas sensing materials is vital. The electron-phonon coupling that derives the electronic structure change with temperatures is a key property of interest as this affects other sensing responses. Herein, we assess the temperature dependence of band gap renormalization in pristine and oxygen-vacant LaCrO_3-δ perovskite employing Allen-Heine-Cardona theory with first-principles simulations, and corroborate with experimental observation. We find fair agreement in temperature-dependent band gap change in LaCrO₃ between theory and an in-house experiment, proving that the theory can adequately predict renormalization on the band gap in the system of interest. Band gaps in high-temperature phase of cubic LaCrO_3-δ are found to be monotonically closed by 1.13 eV in pristine and by around 0.62 eV in oxygen-vacant states as a function of temperature up to 1500 K. The predicted and measured band gap variations are characterized using an analytical model, which can provide useful insights on the simulated zero-temperature band gaps.