Defect regulation of a distinctive synthetic Eu2+-doped SiAlON S-phase towards controllable spectra and thermal quenching for white-light-emitting diode

[Display omitted] •The O vacancy in BaAl1+ySi5-yO2-y/2N7:Eu2+ were effectively regulated.•The regulation method includes control of Eu2+ content and Al/Si ratio.•The defects can effectively regulate the spectra and thermal stability of samples.•The mechanism of oxygen vacancy is analyzed and discussed in detail.•The assembled WLED exhibits lower color temperature and higher color rendering. Targeted control of the luminescent properties of phosphors for white-light-emitting diode (WLED) applications, particularly spectral position and thermal stability, is crucial. In this study, a newly developed Eu2+-doped sialon S-phase BaAl1+ySi5-yO2-y/2N7 with intrinsic O vacancy (Vo) defects was synthesised using a special raw material ratio with an O deficiency. A series of structure–performance characterisations and density functional theory (DFT) calculations were performed. It was found that the spectral position and thermal stability of the samples could be realised by defect regulation using two approaches: regulation of the Eu2+ content and Al/Si ratio. Consequently, the emitting colour of the samples could be adjusted from green to yellow, leading to a lower colour temperature and higher colour rendering in the assembled WLED. The abnormal thermal quenching effect can also be suppressed with less variation in the emission intensity and colour purity at high temperatures. The defect regulation process investigated in this study will hopefully offer novel ideas for improving the luminescence properties of phosphors for extensive WLED applications.