Structure and Photoluminescence Properties of Dy³⁺ Doped Phosphor with Whitlockite Structure

Whitlockite has the advantages of a low sintering temperature, high stability, and a low fabrication cost, and it is widely used as the host for luminescent material. In this study, Ca_1.8Li_0.6La_0.6-x(PO₄)₂:xDy³⁺ phosphor was prepared by the high-temperature solid-state method, and its structure, composition, and luminescence properties were systematically studied. The results showed that a new whitlockite type matrix was prepared by replacing Ca²⁺ in whitlockite with monovalent and trivalent cations. The prepared phosphors belonged to a hexagonal crystal system with a particle size in the range of 5-20 μm. Under the excitation of 350 nm UV light, the samples emitted white light, and there were mainly two stronger emission peaks at 481 nm in the blue band and 573 nm in the yellow band, which correspond to the electron transitions at ⁴F_9/2→⁶H_15/2 and ⁴F_9/2→⁶H_13/2 of Dy³⁺, respectively. The optimal doping concentration of Dy³⁺ in Ca_1.8Li_0.6La_0.6(PO₄)₂ matrix was 0.03 (mol%). The main mechanism of concentration quenching in the sample was dipole-dipole energy transfer. When the temperature was 130 °C, the luminescence intensity of the samples was 78.7% of that at 30 °C, and their thermal quenching activation energy was 0.25 eV. The CIE coordinates of the sample at 30 °C were (0.2750, 0.3006), and their luminescent colors do not change with temperature. All the results indicate that Ca_1.8Li_0.6La_0.6-x(PO₄)₂:xDy³⁺ phosphor is a luminescent material with good luminescence performance and thermal stability, which shows a promising application in the field of LED display.