Far-red-emitting Li6SrLa2Sb2O12: Mn4+ phosphor for plant growth LEDs application

Abstract Novel far-red emission Li6SrLa2Sb2O12: Mn4+ garnet-like phosphors have been synthesized via traditional high-temperature solid-state reaction method. The as-prepared Li6SrLa2Sb2O12: Mn4+ phosphor has a broad excitation band in the range of 300−600 nm with four Gaussian fitting bands peaking at around 325 nm, 364 nm, 429 nm and 501 nm, respectively. It gives far-red emission peaking at 705 nm under both UV and blue-green excitation. The optimum doping concentration of Mn4+ is about x = 0.01 and beyond which the luminescence quenching takes place, caused by the dipole-dipole interaction induced energy transfer among the Mn4+ ions. When the temperature is raised up to 370 K, the emission intensity of Li6SrLa2Sb2O12: 0.01 Mn4+ drops to 50 % of that at room temperature. The investigation shows that Li6SrLa2Sb2O12: Mn4+ is a potential red phosphor matching NUV LED chips for plant growth application.