Host sensitized novel red phosphor CaZrSi_2O_7:Eu ~(3+) for near UV and blue led-based white LEDs

摘要

A series of red phosphors Ca_(1-x)ZrSi_2O_7: Eu_x (x = 0.5,1,5,10,12 mol%) were prepared by a solid-state reaction technique at various temperatures and their structural and optical properties were investigated. The x-ray diffraction profiles showed that all peaks could be attributed to the monoclinic phase CaZrSi_2O_7 doped with Eu~(3+). SEM, FTIR, TG and DTA profiles have also been characterized to explore their structural properties. The luminescence properties of these resulting phosphors have been characterized by photoluminescence spectra. The host matrix itself has shown a strong blue emission which has its maximum intensity at 470 nm. The excitation spectra of CaZrSi_2O_7: Eu~(3+) revealed two excitation bands at 395 and 464 nm which correspond to the sharp~7F_0-~5L_6 and ~7F_0-~5D_2 transitions of Eu ~(3+) and matches well with the two popular emissions from n-UV/blue GaN-based LEDs. The prominent red emission was obtained at 615 nm by the excitation transitions~5L_6, ~5D_2 of Eu~(3+) through the non-radiative energy transfer process from the host to the Eu~(3+) ion. The effects of charge compensation by monovalent ions on the luminescence behaviour of a red emitting phosphor CaZrSi _2O_7: Eu~(3+) were investigated. The high colour saturation and the low thermal quenching effect of these phosphors make it a potential red component for white light emitting diodes (w-LEDs).