Synthesis and luminescence properties of Ca2SiO4-based red phosphors with Sm3+ doping for white LEDs

Sm3+-activated Ca2SiO4 red phosphors were prepared by the conventional high-temperature solid-state reaction method, and the effects of sodium (Na+) and samarium (Sm3+) ions doping concentrations on their crystal structure and luminescent properties were investigated by X-ray diffraction (XRD) and fluorescent spectrofluorometer. XRD patterns demonstrate that a well-crystalline structure forms in the phosphors when they are treated by calcination at 1200°C for 4 h, and the excitation spectra exhibit good absorption in the range between 350 and 420 nm. Under the irradiation of 405 nm near-ultraviolet (NUV) light, the spectra of the phosphors show a main emission peak at 601 nm attributed to the 4G5/2→6H7/2 transition of Sm3+ ions, and its intensity is greatly influenced by the concentrations of Sm3+ and Na2CO3. When the concentrations of Sm3+ ions and Na2CO3 are 2mol% and 6mol%, respectively, the optimal emission intensity can be obtained. From strong absorption in the near ultraviolet zone, the Na0.06Sm0.02Ca1.92SiO4 phosphor is a promising red-emitting phosphor for white light emitting diodes (W-LEDs).