Luminescence and Concentration Quench Mechanism of Eu~(3+) in LiSrPO_4

The red phosphor LiSrPO4∶Eu3+ for white LEDs was synthesized by high temperature solid state reaction.The emission and excitation spectra were investigated.The emission spectra showed a series of sharp peaks,in which the strongest one appeared at 616 nm.The excitation spectrum monitored at 616 nm contained two excitation bands,weak charge transition band Absorption CTS(220-310 nm)and strong f→f transition Absorption(310-500 nm)of Eu3+.The strongest peak located at 393 nm which was coupled well with the emission of InGaN(350-410 nm).There were some differences in emission spectra of Eu3+ in LiCaPO4,LiSrPO4 and LiBaPO4.The symmetry of crystal lattice sites which Eu3+ occupied were enhanced by order of Ca,Sr,Ba.Concentration quenching occurred as a result of quadrupole-quadrupole interaction according to Dexter's theory.Li+,Na+ and Cl-could all enhance the light emit intensity when used as charge compensations.The LiSrPO4∶Eu3+ phosphor was a potential red-emitting phosphor for white LEDs.