Theoretical investigations of electronic and thermodynamic properties of Ce doped La2Zr2O7 pyrochlore

With ab-initio calculations, the geometrical structure, electronic band structure, optical and thermodynamic properties of pure and Ce doped La2Zr2O7 are calculated. Doping Ce at Zr site modified the intrinsic band gap of La2Zr2O7. However, increasing the Ce doping concentration has no considerable effect on the band structure. With the increase in Ce doping concentration, the absorption spectra of the doped La2Zr2O7 is shifted to higher wavelengths and the peaks intensity is reduced. Some of the peaks associated with the intrinsic La2Zr2O7 are disappeared and new peaks are introduced in 3.40% Ce doped La2Zr2O7. Perturbations in the phonons density of states are reduced with the increasing Ce doping concentration. The La16Zr13Ce3O56 system with 3.40% of Ce doping provided the most stable phonons curve among the simulated systems. Interesting behavior is observed in the thermal conductivity of the doped models with the increasing temperature. The thermal conductivity of La16Zr13Ce3O56 model increases compared to the pure La2Zr2O7. However, further increase in the Ce doping concentration drastically reduced the thermal conductivity values in the range 373-1673 K. The La16Zr13Ce3O56 system (3.4% Ce) provided the lowest thermal conductivity attributed to the high concentration of point defects affecting the phonon scattering.