Thermal stability of luminescence of NaCaPO4 : Eu2+ phosphor for white-light-emitting diodes

A green-emitting phosphor, Eu2+-activated NaCaPO4, was synthesized by the conventional solid-state reaction. The photoluminescence excitation and emission spectra, and the temperature dependence of luminescence intensity of the phosphor were investigated. The results showed that NaCaPO4 : Eu2+ could be efficiently excited by incident light of 280-420 nm, which matched well with the emission wavelengths of near-UV LED chips. NaCaPO4 : Eu2+ has a higher quenching temperature. With an increase in the temperature, the emission bands of NaCaPO4 : Eu2+ show an abnormal blue-shift with broadening bandwidth and decreasing emission intensity. The phosphor has a promising potential for white-light-emitting diodes pumped by ultraviolet chips. The CIE coordinates and luminescence decay (lifetimes) of Eu2+ ions in this monophosphate were discussed in order to further investigate the potential applications.