High thermally Sm3+-activated SrBi2Ta2O9 orange-red phosphor: Preparation, characterization, and optical properties

A new orange-red SrBi2Ta2O9:Sm3+ phosphor is prepared via high-temperature solid-state route in air atmosphere. The phase purity of phosphor is characterized using X-ray diffraction (XRD). The phosphor shows the intense excitation peak at 403 nm and emits bright orange-red light at 564, 600, 647, and 701 nm in photoluminescence (PL) spectrum. Among them, the strongest peak is located at 600 nm due to (4)G(5/2)- H-6(7/2) transition of Sm3+. The critical transfer distance of Sm3+ is calculated as 26.31 angstrom. The optimal doping concentration is determined to be about 2 mol%. The temperature dependent emission spectra exhibit excellent thermal stability. The Commission International de L'Eclairage (CIE) coordinates of the SrBi2Ta2O9:xSm(3+) (0.005 <= x <= 0.30) are located in the reddish orange region. These results indicate that the orange-red emitting SrBi2Ta2O9:Sm3+ phosphor can be used as potential substitute red phosphors for white light emitting diodes (w-LEDs).