Spectroscopic investigation on tunable luminescence by energy transfer in Tb2−xSmx(MoO4)3 nanophosphors

Abstract New Sm 3+ activated Tb 2 − x Sm x (MoO 4 ) 3 nanophosphors were synthesized through sol–gel method. The structural and luminescence properties have been studied by XRD, TEM and photoluminescence measurements. The XRD pattern confirms that the Tb 2 − x Sm x (MoO 4 ) 3 crystallizes in the same orthorhombic structure of Tb 2 (MoO 4 ) 3 . The spectroscopic and laser parameters of Sm 3+ ion in Tb 2 − x (MoO 4 ) 3 matrix were evaluated for the first time using Judd–Ofelt theoretical analysis. The higher value of stimulated emission cross-section of 4 G 5/2 → 6 H 7/2 transition of Sm 3+ is favorable for low threshold and high gain to obtain continuous wave laser action. The photoluminescence excitation spectra suggest that this novel phosphor can be excited over a broad range from nUV to blue light (300–490 nm). Under the excitation of UV, Tb 2 − x Sm x (MoO 4 ) 3 nanophosphor exhibits the characteristic emissions of Tb 3+ and Sm 3+ . By varying the doping concentration of Sm 3+ , the emission color of the phosphors can be tuned and white emission in a single composition can be obtained under host excitation, in which an energy transfer from MoO 4 2 − → Sm 3+ / Tb 3+ and Tb 3+ → Sm 3+ was observed. The investigation of the luminescence decay curves and lifetime values implies the energy transfer between Tb 3+ → Sm 3+ and confirms the absence of Sm 3+ → Tb 3+ energy transfer. These phosphors might be a promising material for use in nUV LEDs and can exhibit tricolor luminescence under single excitation wavelength.