Rare Earth Doped Lanthanum Calcium Borate Polycrystalline Red Phosphors

Abstract

Single-phased Sm3+doped lanthanum calcium borate (SmxLa2−xCaB10O19, SLCB,x=0.06) polycrystalline red phosphor was prepared by solid-state reaction method. The phosphor has two main excitation peaks located at 398.5 nm and 469.0 nm, which are nicely in accordance with the emitting wavelengths of commercial near-UV and blue light emitting diode chips. Under the excitation of 398.0 nm, the dominant red emission of Sm3+in SLCB phosphor is centered at 598.0 nm corresponding to the transition of4G5/2 → 6H7/2. The Eu3+fluorescence in the red spectral region is applied as a spectroscopic probe to reveal the local site symmetry in the host lattice and, hence, Judd-Ofelt parametersΩt  (t=2, 4)of Eu3+in the phosphor matrix are derived to be3.62×10-20and1.97×10-20 cm2, indicating a high asymmetrical and strong covalent environment around rare earth luminescence centers. Herein, the red phosphors are promising good candidates employed in white light emitting diodes (LEDs) illumination.