Structural phase transition and charge carrier dynamics in Dy containing La6MoO12 ionic conductor

The solution combustion method was adopted to prepare a single-phase La6MoO12 compound by doping 10% Dy in the La site and sintered at 800 degrees C, 1000 degrees C, and 1200 degrees C temperatures. The X-ray diffraction patterns confirmed a phase transition of the samples from the cubic fluorite phase (Fm3m) to a complex rhombohedral structure (R3m) with increasing sintering temperature. The microstrain and particle size show the opposite behaviour in the case of 800 degrees C and 1200 degrees C sintered samples. The FE-SEM and XRD results corroborated the increment of particle size with sintering temperature. Elemental mapping confirmed the uniform distribution of elements in the compositions. Red and blue shifts in optical bandgap were observed with sintering temperature. All samples show a negative temperature coefficient of resistance (NTCR) behaviour. The sample sintered at 1200 degrees C has the highest ionic conductivity of 1.03 x 10-4 omega-1cm- 1 at 540 degrees C. The reciprocal temperature dependence of conductivity followed the VTF equation. The dielectric loss tangent indicated that all samples have a single relaxation process. The time-temperature superposition principle has been verified from the scaling of the dielectric loss tangent.

Automated summary

The solution combustion method was used to prepare a single-phase La6MoO12 compound doped with 10% Dy. The samples were sintered at different temperatures and their phase transition, microstructure, optical properties, and ionic conductivity were investigated. The results showed that the sintering temperature played a significant role in determining the structural and functional properties of the samples.