Preparation And Study Of Properties Of Rare-earth Doped Ca₃Si_3－xO_3+xN_4－2x Oxynitride Phosphors

As a kind of Solid-State White Lighting,light emitting diode（LED）has played an important role in the lighting field since 1960s.The key is that it has many advantages such as low energy consumption and Environmentally Friendly.With great progress made in phosphor technologies,LEDs are now penetrating steadily into the light market and replacing conventional light sources in a very broad range.Generally,the applications of LEDs fall into the following major categories:indicators,traffic signals,decorative holiday lights,exit signs,electric signage,and rear lamps of autos,backlighting for LCDs and lightweight laptop displays.Phosphor is the key to improve the performance of LEDs.Among all kinds of phosphors,oxynitride phosphor is considered to be promising for its outstanding performance.In this study,Ce³⁺doped Ca₃Si₂O₄N₂:Ce³⁺phosphor and Ce³⁺,Tb³⁺co-doped Ca₃Si₂O₄N₂:Ce³⁺,Tb³⁺phosphor were prepared by the high temperature solid reaction.The phase composition was identified by X-ray diffraction.The excitation and emission spectra,reflectance spectra and thermal stability were investigated in detail,respectively.Results show that Ca₃Si₂O₄N₂:Ce³⁺phosphor can be excited by UV-vis light in the broad range of 350-380 nm and exhibited a broad emission with peaks at 460nm.Redshift can be observed with increase of Ce³⁺concentration.Ca₃Si₂O₄N₂:Ce³⁺phosphors can serve as a potential blue-emitting phosphor for applications in near-UV w-LEDs.As the increase of x,the excitation spectra of Ca₃Si_3-xO_3+xN_4–2x:Eu²⁺phosphors show an obvious blue-shift from 337 to 323nm.When x reach up to 0,a significant red shift of excitation spectrum can be observed,and the width of the excitation spectrum become broader.This novel phosphor can been effectively excited by lights between 365-375nm.The energy transfer happened between Ce³⁺and Tb³⁺in Ca₃Si₂O₄N₂:Ce³⁺,Tb³⁺phosphor.With increase of Ce³⁺concentration,CIE chromaticity coordinate shifts from blue to blue-green region.With excellent thermal stability,it can be used as blue-emitting phosphor in near-UV w-LEDs.