Studies on optical properties of LiCaBO₃: Tb³⁺ phosphor

The green emitting phosphor LiCaBO₃:Tb³⁺ has been synthesized by easy, time saving, cost effective modified method of solution combustion synthesis at comparatively lower temperature using urea as fuel. X-ray power diffraction (XRD) analysis confirms the formation of the said phosphor. Photoluminescence measurements show that the phosphor has exhibited emission peak with good intensity at 547 nm, corresponding to 5D4– 7 F5 (547 nm) green emission and weak 5D4– 7 F5 (486 nm) blue emission. The excitation spectra monitored at 547 nm show broad band from 250 to 300 nm ascribed to spin-allowed 4f8 –4f7 5d transitions of Tb³⁺ . Also, no charge-transfer (CT) transition related to Tb³⁺ -O₂^- has been observed. For the excitation wavelength of 240 nm the emission intensity increases initially with the increase of Tb³⁺ concentration and reaches to the maximum at x=0.005. The concentration quenching observed after that is mainly due to quadrupole– quadrupole interaction. The as synthesized phosphor LiCaBO₃:Tb³⁺ by this method shows CIE colour coordinates of (0.28, 0.71) with good intensity (author)