Crystal Structure of High-Temperature Phase β-NaSrBO3 and Photoluminescence of β-NaSrBO3:Ce3+

α-NaSrBO3 is an excellent phosphor host for phosphor-converted white light-emitting diode (w-LED) application with very interesting properties. However, it undergoes a phase transformation to β-NaSrBO3 at the LED working temperature. In this study, the high-temperature phase β-NaSrBO3 was stabilized to room temperature by introducing Na+ and Ce3+ via a high-temperature solid-state reaction method. The crystal structure of β-NaSrBO3 was determined from the powder X-ray diffraction data. It crystallizes in space group P21/c with the following lattice parameters: a = 6.06214(8) A, b = 5.41005(7) A, c = 9.1468(1) A, β = 102.116(1)°, and V = 293.301(7) A3. Na and Sr sites are found to be mixed occupied by each other, and the isolated [BO3]3– anionic groups are distributed in parallel. Ce3+-activated β-NaSrBO3:Ce3+ blue-emitting phosphors were synthesized. The temperature-dependent photoluminescence spectra indicate that the thermal stability of β-NaSrBO3:Ce3+ is better than that of α-NaSrBO3:Ce3+ at the same t...