Luminescence investigation of Eu3+–Sm3+ co-doped Gd2−x−yEuxSmy(MoO4)3 phosphors as red phosphors for UV InGaN-based light-emitting diode

Gd2−x−yEuxSmy(MoO4)3 (x = 0, 0.20, 0.40, 0.60, 0.80, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0, and y = 0, 0.020, 0.024, 0.028, 0.032, 0.036, 0.040) were prepared by solid-state reaction technique at 800 °C and 950 °C respectively; two types of host structure (monoclinic structure for 800 °C and orthorhombic structure for 950 °C) were obtained. The photo-luminescent results show that Gd0.372Eu1.6Sm0.028(MoO4)3 with orthorhombic structure exhibits the most intense red-emitting under near UV excitation. In the Eu3+–Sm3+ co-doped system, both Eu3+ and Sm3+ f–f transition absorptions are observed in the excitation spectra, the intensities of the main emission line (5D0 → 7F2 transition of Eu3+ at 615 nm) are strengthened because of the energy transition from Sm3+ to Eu3+. With the broadened absorption around 400 nm, strengthened emission intensity at 615 nm and the appropriate chromaticity coordinates (x = 0.65, y = 0.33), the phosphor Gd0.372Eu1.6Sm0.028(MoO4)3 was combined with a ∼400 nm emitting InGaN chip to obtain an intense red-emitting LED finally.