Preparation and spectroscopic properties of La2Hf2O7/Tb

Poorly crystallized La2Hf2O7 powders doped with different Tb concentrations were directly synthesized through a combustion process, using glycine as a fuel. Single-phase and well-crystallized cubic pyrochlore La2Hf2O7:Tb phosphors were obtained after calcinations at 1500 °C. The combustion-made powders could be easily sintered to transparent ceramic La2Hf2O7:Tb in H2 atmosphere at 1900 °C. The PL excitation and emission spectra were recorded for both types of the materials. Emission spectra of both type of the materials were found to be typical for Tb3+, resulting from radiative relaxation of 5D3 and 5D4 levels, and the integrated emission intensity ratio of 5D3 to 5D4 decreases with the increase of Tb3+ concentration due to the cross-relaxation between Tb3+ ions. The excitation spectra revealed that the energy absorbed by the photoionization of Tb3+ can be transferred to the dopant much more efficiently in the transparent ceramic La2Hf2O7:Tb than in powders.