High temperature oxygen NEXAFS valence band spectra and conductivity of LaFe3/4Ni1/4O3 from 300 K to 773 K

TL;DR

This study investigates how high-temperature oxygen NEXAFS spectra relate to electrical conductivity in LaFe3/4Ni1/4O3 from 300 K to 773 K, revealing temperature-dependent charge transfer and polaron transport mechanisms.

Contribution

It provides new insights into the temperature-dependent electronic structure and charge transfer processes in LaFe3/4Ni1/4O3 using NEXAFS spectroscopy.

Findings

Spectral weight of Ni-related pre-edge peaks peaks at around 600 K.

Charge transfer from O(2p) to Ni(3d) increases with temperature.

Pre-edge features partly explain polaron-activated transport.

Abstract

LaFe3/4Ni1/4O3 was subjected to oxygen near edge x-ray absorption fine structure (NEXAFS) spectroscopy for 300 K < T < 773 K. The spectra show in the pre-edge a small hole doped peak originating from Ni substitution. The relative spectral weight of this transition to the weight of the hybridized O(2p) - Fe(3d) transitions scales with T and has a maximum at around 600 K. The characteristic energies of the thermal activated spectral intensity and conductivity suggest that the concentration of charge transferred electrons from O(2p) to Ni(3d) increases and that the pre-edges account in part for the polaron activated transport.