Ca4Gd(BO3)3O:Tb3+ 형광체의 에너지 전달 및 형광특성 연구

Abstract

Tb3+-doped Ca4Gd(BO3)3O phosphors were synthesized by solid-state reaction at high temperature in the air atmosphere. The starting chemicals were CaCO3 99 %, H2BO3 99.5 %, Gd2O3 99.99 % and Tb4O7 99.9 %. The formation of single-phase Ca4Gd(BO3)3O were confirmed by X-ray powder diffraction analysis. No obvious impurity phase was observed. The emission and excitation spectra of Ca4Gd(BO3)3O:Tb3+ (0.1, 1, 10, 15 mol %) are investigated under the ultraviolet (UV) excitation at room temperature. The excitation lines due to the 8S7/2 → 6IJ and 6PJ transitions of Gd3+ are observed at around 277 and 315 nm in the excitation spectrum of Ca4Gd(BO3)3O:Tb3+. Intense green emissions due to the 5D4 → 7FJ (J = 3, 4, 5, 6) transitions of Tb3+ are observed under the UV excitation. The relative intensity of the emission due to the 5D3 → 7FJ (J = 4, 5) and 5D4 → 7FJ (J = 3, 4, 5, 6) transitions under excitation at 277 nm depend strongly on the Tb3+ concentration in Ca4Gd(BO3)3O. Particularly, the green emission transition 5D4 → 7F5 at 486 nm has been found to the be more prominent and intense. It is found that the energy transfer from Gd3+ to Tb3+ occurs in Ca4Gd(BO3)3O:Tb3+ for UV excitation. The maximum luminescence intensity of Ca4Gd(BO3)3O:Tb3+ is obtained at the Tb3+-concentration of 10 mol%.