Correlation between local structure and electronic properties of BaZrO3:TbYb Optical Ceramics

Deep knowledge on electronic and structural properties allows building electronic and optical devices for specific applications, such as light emitting diodes, laser transistors, gas sensors and solar cells. In this work, we present a discussion about the local and global distortions on the structural and electronic levels for undoped and Tb/Yb co-doped BaZrO3 (BZO), synthesized via microwave assisted hydrothermal method. A structural investigation demonstrates that the main crystalline phase in all preparations is the cubic BaZrO3, associated with low intensity minority phases, such as BaCO3 and KCl, mainly when the doping concentration increases. Raman spectroscopy results presented vibrational modes associated with secondary structures and with the distortions in the lattice induced by the Tb3+ and Yb3+ ions. The particles size decreased, and they became irregularly shaped as a function of the doping ions concentration. X-ray absorption near edge structure (XANES) analysis around the Zr-LII and LIII edges showed through the B/A ratio, the doping ions induce distortions in the ZrO6 clusters. This last effect indeed can be interpreted by application of crystalline field effects associated to spin-orbit coupling on energy levels for modified Zr environments by the presence of Tb/Yb ions. Typical Tb3+ and Yb3+ transitions were assigned in photoluminescence spectra confirming the dopant incorporation in the host lattice. The comprehension of structural end electronic features on the crystalline field establishes a solid basis for further studies of co-doped BZO in optical applications.