Synthesis and luminescent characteristics of yellow emitting GdSr ₂AlO₅:Ce³⁺ phosphor for blue light based white LED

A series of Ce³⁺ ions doped GdSr₂AlO₅ (GSA) phosphors were synthesized by a citric acid based sol-gel method. The X-ray diffraction patterns confirmed their tetragonal structure after the samples were annealed at 1300 C, and the scanning electron microscope image showed the closely packed particles. The excitation spectra revealed that the GSA phosphor effectively excited with blue light of 442 nm due to the 4f ¹→5d¹ transition and exhibited yellow emission corresponding to the 5d¹→4f¹ transition of Ce ³⁺ ions. The optimum doping concentration of Ce³⁺ ions was 5 mol% and the critical distance was calculated to be ∼17 Å. White LEDs were fabricated by combining blue LED (465 nm) chip with Ce ³⁺:GSA phosphor. The CIE chromaticity coordinates (0.34, 0.31) provide their emission potentiality in the white light region.