Abstract: A method of synthesizing a composite phosphor by phase transition, characterized by controlling the sintering temperature and duration, changing M2?ySi5N8:Ry phase to M1?xSi6N8 : Rx phase, thereby forming a two-phase composite phosphor, wherein proportions of the two phases of the composite phosphor are variable. As indicated by its varying CIE color coordinates, Sr1.98Si5N8:Eu2+0.02 changes from red to pink, and then to blue. The CIE color coordinates are collinear. If there is no color deviation at the two ends of the straight line, the coordinates of any color resulting from a mixture of two colors will lie on the straight line. The aforesaid synthesis method dispenses with the hassles of sintering two colored phosphors separately, thus attaining uniformity of resultant light color and cutting the costs of phosphor synthesis.

Abstract: The high color rendering index (CRI) and high thermal properties of the red nitride phosphor are proposed in the invention. The phosphor would keep the original crystal phase and reduce the change of crystal volume by replacing different atoms. In addition, the red nitride phosphor can be excited by an incident light with wavelength ranging from 370 nm to 470 nm, and that shows the red phosphor of the present invention can be applied in white light emitting diodes. Moreover, the red nitride phosphor proposed by the present invention includes the potential application in main peak modulation and FWHM adjustment, and would be helpful to improve the thermal stability problem of white light emitting diodes.