Enhancement of photoluminescence intensity of sintered CaAlSiN ₃ :Eu ²⁺ red phosphor‐bismuthate glass composites

Abstract Wavelength converters in white light‐emitting diodes are usually made by sintering of phosphor‐glass powder compacts. An issue is that the sintering process usually results in the reduction of phosphor amount. In the present study, composites containing CaAlSiN ₃ :Eu ²⁺ red phosphor and Bi ₂ O ₃ ‐B ₂ O ₃ ‐ZnO‐Sb ₂ O ₅ glass were fabricated by sintering method. Influences of CaAlSiN ₃ :Eu ²⁺ phosphor content (10 vol%–30 vol%) and sintering temperature (410–430°C) on the residual amount of the phosphor phase and the resulting luminescence intensity of the composites were investigated. The change of CaAlSiN ₃ :Eu ²⁺ content due to sintering was analyzed by X‐ray diffraction. The interdiffusion between the CaAlSiN ₃ :Eu ²⁺ and glass matrix was examine by scanning electron microscope equipped with energy dispersive X‐ray spectrometry. This paper focuses on the change of luminescence intensity after sintering. It was found that although the content of phosphor CaAlSiN ₃ :Eu ²⁺ reduces after sintering; the luminescent intensity of the composites anomalously increases. The optimum luminescence intensity is 14% higher than that of the as‐mixed, unfired powder. It is proposed that the incorporation of Bi ³⁺ ions from the glass matrix into the phosphor CaAlSiN ₃ :Eu ²⁺ during sintering improves the luminescence ability of the phosphor particles.