Improvement of Temperature Dependence of Eu²⁺-Doped Red-Emitting Sr-Containing Sialon Phosphor by Control of Host-Crystal Composition

To improve the temperature dependence of red-emitting Sr-containing phosphor Sr2Si7Al3ON13:Eu2+ with longer wavelength emission that is preferable for high color rendering, control of the host-crystal composition was attempted. Substitution of Si-N for Al-O caused the emission peak wavelength to shift from 613 nm to 628 nm without increasing of Eu2+ concentration, because of increase of the centroid shift and the crystal-field splitting. We found that the activation energy of the thermal quenching slightly increases with the increase of the emission wavelength, otherwise the probability of the thermal quenching increases sharply with the increase of Eu2+ concentration, and therefore the substitution of Si-N for Al-O of this phosphor has achieved the long wavelength emission of around 630 nm and the excellent temperature dependence. These results indicate this red-emitting phosphor Sr2Si7+xAl3+xO1-xN13+x:Eu2+ has great potential for high-color-rendering white LED.