Luminescence and Quantum Efficiencies of Eu 3+ ‐Doped Vanadate Garnets

Nondoped and 5.0 mol% Eu 3+ ‐doped vanadate garnets Ca 5 Mg 4 ( VO 4 ) 6 , NaCa 2 Mg 2 [ VO 4 ] 3 , KCa 2 Mg 2 [ VO 4 ] 3 , and NaSr 2 Mg 2 [ VO 4 ] 3 were synthesized by solid‐state reactions. The formation of single‐phase compound with garnet structure is confirmed by X‐ray diffraction. The photoluminescence ( PL ) and PL excitation ( PLE ) spectra are investigated together with color coordinates. The luminescence process is discussed on the charge‐transfer transitions in [ VO 4 ] 3− ions and the crystal structure. The PL quantum efficiencies ( QE ) are measured for nondoped and Eu 3+ ‐doped samples. The Eu 3+ ‐doped samples have higher QE s than the corresponding nondoped ones although the energy transfer occurs from [ VO 4 ] 3− to Eu 3+ . Broad emission band due to [ VO 4 ] 3− with intense sharp lines due to Eu 3+ , which gives white color, is observed in Eu 3+ ‐doped NaCa 2 Mg 2 [ VO 4 ] 3 and NaSr 2 Mg 2 [ VO 4 ] 3 under excitation with UV light. These materials are suggested to be useful for lighting under the excitation with near‐ UV LED .