Structural and charge carrier dynamics study of Dy stabilized La6MoO12 ionic conductors

Room temperature single phase stabilization of different metals (Zr, Cd, and Ca) doped La6MoO12 compound was achieved by incorporating Dy2O3 using the solution combustion method. Rietveld refined X-ray diffraction profiles showed cubic fluorite (Fm3m) structure for all the compositions. The optical bandgap, calculated from ultraviolet-visible spectra, exhibited blue shifts with decreasing dopant ionic radius. The photoluminescence spectra confirmed the charge carrier's various trapping or defect states. The complex impedance plot exhibited non-Debye-type relaxation with a negative temperature coefficient of resistance (NTCR). It also indicated that the dopant might act as an acceptor or donor depending upon its valency. The ac conductivity was found to follow the small polaron hopping mechanism. A thermally activated single relaxation process was observed. The composition La5.4Dy0.4Zr0.2MoO12.1 showed the highest conductivity, 1.05 x 10-4 ohm- 1 cm-1 at 680 degrees C. The scaling of spectra indicated temperature and composition independent charge carrier mechanism.

Automated summary

Room temperature single phase stabilization of different metals (Zr, Cd, and Ca)-doped La6MoO12 compound was achieved by incorporating Dy2O3. The X-ray diffraction profiles confirmed the cubic fluorite (Fm3m) structure. The optical bandgap decreased with decreasing dopant ionic radius. The photoluminescence spectra indicated various trapping or defect states for the charge carriers. The complex impedance plot showed non-Debye-type relaxation and negative temperature coefficient of resistance (NTCR), suggesting the dopant's role as an acceptor or donor. The ac conductivity followed the small polaron hopping mechanism, and a thermally activated single relaxation process was observed. The composition La5.4Dy0.4Zr0.2MoO12.1 exhibited the highest conductivity at 680 degrees C.