[Preparation and luminescent properties of a green Ca2SnO4 : Tb3+ phosphor]

A novel green emitting phosphor, Tb(3+)-doped Ca2SnO4, was prepared by the solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the formation of Ca2SnO4 : Tb3+. Photoluminescence measurements indicated that the phosphor exhibits bright green emission at about 543 nm under UV excitation. The excitation spectra of Ca(2-x)Tb(x)SnO4 appear to have a red shift with main peak from 254 to 260 nm. The emission spectra of Ca(2-x)Tb(x)SnO4 have four peaks ascribed to 5D4-7F(J) (where J = 6, 5, 4, 3) transitions of Tb3+ ions. Under the condition of low Tb3+ concentration, the 5D4-7F6 transition of Tb3+ showed a stark energy level split to three split peaks and the peak intensity of 481nm firstly increased with increasing Tb3+ concentration, then decreased. The dependence of luminescent intensity of Ca2 SnO4 : Tb3+ phosphor on the Tb3+ concentration was studied, and the results show that the luminescence intensity firstly increased with increasing Tb3+ concentration, then decreased, and reached the maximal value at 9 mol% Tb3+. According to the Dexter theory, the authors confirmed the concentration quenching mechanism of Tb3+ in Ca2 SnO4. The fluorescence lifetime of phosphor analysis shows that the average lifetime is 4.4 ms. The results indicated that Ca2 SnO4 : Tb3+ could be a potential candidate as a green-emitting powder phosphor.