First-principles quantum investigations on rare-earth based pyrochlore oxides RE2Th2O7 (RE = Nd, Pr) for optoelectronics, thermoelectric, and spintronics applications

Abstract

Pyrochlore oxides are progressively becoming potential candidates for thermoelectric power generation and solar energy owing to their unique electronic structures that are advantageous for optoelectronic and thermoelectric characteristics. The spintronic, optoelectronic and thermoelectric properties of novel pyrochlore oxides including RE₂Th₂O₇ (RE = Nd, Pr) are analyzed to evaluate their potential for industrial applications. All Calculations are performed using ab-initio calculations based on density functional theory (DFT) approach. Nd₂Th₂O₇ and Pr₂Th₂O₇ are direct bandgap semiconductors with energy bandgaps of 2.88 and 2.79 eV, respectively, in both spin channels. Their paramagnetic behavior is analyzed, and magnetic moments can be deduced by examining band patterns perceived in energy band structures of RE₂Th₂O₇ (RE = Nd, Pr) associated electronic states in spin up and spin down channels. Significant values of magnetic moments (\({\mu }_{B}\)) for Nd₂Th₂O₇ and Pr₂Th₂O₇ are 12.0 and 7.001, respectively. RE₂Th₂O₇ (RE = Nd, Pr) show a significant absorption of incident photons in the near-UV constituency in both spin channels. The optical reflectivity spectra \(R(\omega )\) for RE₂Th₂O₇ (RE = Nd, Pr) exhibit a lower reflectance value of about 20% within presented energy range. The positive values of Seebeck coefficient (\(S\)) indicate p-type semiconducting behavior of RE₂Th₂O₇ (RE = Nd, Pr). Nd₂Th₂O₇ is promising candidate for thermoelectric device applications as its ZT value is 0.99.