Abstract
Sm3+-doped LnNbO4 (Ln=La, Y) phosphors were obtained by high-temperature solid-state reaction. The crystal structure of LnNbO4:Sm3+ (Ln=La, Y) was characterized by X-ray diffraction. Luminescent properties of those phosphors were investigated by diffuse reflection spectra, excitation spectra, as well as emission spectra. The emission spectra of those phosphors consisted of several orangish-red emission bands around 550–670 nm upon the excitation at 405 nm, and the luminescent emission intensity of LaNbO4: Sm3+ was much stronger than that of YNbO4: Sm3+. The 87.0% energy transfer efficiency from the host to Sm3+ ions was observed in LaNbO4: Sm3+ phosphor. Furthermore, the critical transfer distance was calculated and the CIE chromaticity coordinates of LaNbO4: Sm3+ samples were in the range of orangish-red. The fluorescence lifetimes of as-prepared LaNbO4: Sm3+ samples were within the millisecond range and the temperature-dependent luminescence indicated LaNbO4: Sm3+ was highly thermal-stable. Our results indicated that novel orangish-red-emitting LnNbO4: Sm3+ (Ln=La, Y) phosphors were expected to have great potential in white LEDs.
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