Synthesis and characterization of Mg2SiO4:Tb3+, Eu3+ phosphors for white light generation

摘要

The effect of Eu3+ codoping on the structural, morphological, and optical properties of Mg2SiO4:Tb3+ was investigated. The phosphor powders were synthesized by changing the molar concentration of Eu3+ at a fixed Tb3+ content of 5 mol% by using a conventional solid-state reaction. The X-ray diffraction patterns revealed that the crystal structure of all the phosphors, irrespective of the Eu3+ and the Tb3+ contents, showed an orthorhombic structure, and the surface morphology exhibited pebble-like crystalline grains. The emission spectra of Eu3+ and Tb3+-codoped Mg2SiO4 phosphors under an ultraviolet excitation of 252 nm consisted of one intense red band at 619 nm and five weak bands at 448, 488, 598, 658, and 707 nm originating from the transitions of Eu3+, in addition to the several emission bands located at 492, 552, 592, and 628 nm arising from the transitions of Tb3+. As the Eu3+ content was increased, the intensity of the main green emission band at 552 nm decreased markedly and disappeared at 10 mol% Eu3+, when complete energy transfer from Tb3+ to Eu3+ was observed. The results suggest that the emission wavelength and the luminescent intensity of the phosphors can be tuned by modulating the Eu3+ and the Tb3+ contents incorporated into the host matrix.