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

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.