Development of Dy³⁺-doped Gd₂MoB₂O₉ phosphor and their luminescence behavior

In this work, the Gd₂MoB₂O₉ and Gd₂MoB₂O₉:Dy³⁺ phosphors have been prepared by solid state reaction and their structural and luminescence properties have been studied. The Gd₂O₃, MoO₃, H₃BO₃ and Dy₂O₃ were used as starting materials and homogeneously mixed with appropriate ratio. The mixed materials were pressed at 20 tons and sintered at 800, 850, 900, 950, 1000, 1050 and 1100°C. The Gd₂MoB₂O₉ phase was confirmed by X-ray diffractometer (XRD). The photoluminescence spectra measured by 257 nm excitation show one emission peak at 310 nm corresponding to ⁶P_7/2→⁸S_7/2 of Gd³⁺, and four emission peaks of Dy³⁺ at 478, 575, 663 and 754 nm corresponding to ⁴F_9/2 → ⁶H_15/2, ⁶H_13/2, ⁶H_11/2 and ⁶H_9/2 transitions, respectively. The chromaticity coordinates under excitation of λ_ex = 352 nm are (0.48, 0.42), which lies in the white region of CIE 1931 chromaticity diagram. The radioluminescence property was studied by 50 kV, 30 mA X-ray irradiation and compared with commercial BGO crystal. It was found that the integral scintillation efficiency showed 76% of BGO. This result suggests that the developed phosphor may be used in W-LEDs and X-rays imaging applications.