Synthesis and photoluminescence properties of new garnet-type red-emitting Li7La3-xZr2O12:xEu3+ phosphors

Abstract The structural and photoluminescence (PL) properties of as-synthesized and aged garnet-type Li7La3-xZr2O12:xEu3+ (0.02 ≤ x ≤ 0.10) phosphors for white light-emitting diode applications were systematically investigated. Li7La3Zr2O12 oxides satisfied the criteria, proposed by F. C. Hawthorne, for the formation of garnet structure. Rietveld refinement results showed that the as-synthesized Li7La3-xZr2O12:xEu3+ phosphors formed a tetragonal crystal structure (I41/acd space group) and emitted efficient red light. The aging of the Li7La3-xZr2O12:xEu3+ phosphors induced a gradual transition from the tetragonal to the cubic structure and formed a secondary phase Li2CO3, which yielded a substantial decrease in PL excitation and emission intensities.