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 La₁₆Zr₁₅CeO₅₆ 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. (paper)