Preparation and luminescence properties of NaLa(WO4)2:Sm3+ orange-red phosphor

Abstract

Synthesize a series of NaLa(WO4)2:Sm phosphors in different pH and Sm3+ mole contents by using the hydrothermal method. Analyze and characterize the crystal structure, morphological structure, luminescence property, quantum efficiency and chromaticity coordinates of the sample by means of X-ray diffractometer (XRD), scanning electron microscope (SEM and EDS), fluorospectro photometer (FL), Fourier transform infrared spectrometer (FI-IR) and HORIBA Fluoromax-4 fluorescence spectrometer. The analysis results show that all the products obtained are in the scheelite-type structure of tetragonal system, and the morphological structure of them is a sphere or spheroidicity composed of nanoflakes. The product excites at 403 nm NUV, the emission spectrum has 4 emission peaks which are located at 568 nm, 605 nm, 647 nm and 707 nm respectively and belong to 4G5/2→6HJ/2 (J = 5, 7, 9, 11) transition of Sm3+. The luminescence intensity of the product increases and then decreases with the increase of Sm3+ mole content; when the Sm3+ mole content is 2~3%, the fluorescence intensity reaches the maximum value and the strongest peak is located at 647 nm; when the Sm3+ mole content is more than 3%, the concentration quenching occurs. The analysis determines the electric dipole-electric dipole interaction as the type of energy transfer between samarium ions, and the critical distance of energy transfer is 2.196–2.514 nm. The quantum efficiency of the best product is 34.47%, and the chromaticity coordinates show that NaLa(WO4)2:Sm phosphor is orange red and can be used as the potential orange red phosphor for LED.