柠檬酸凝胶燃烧法合成YAG∶Ce,RE荧光粉及其光谱性能研究

Photoluminescence Properties of YAG∶Ce,RE Phosphors Prepared by Citric Acid Gel Combustion Method

以柠檬酸为螯合剂和燃料,采用溶胶凝胶燃烧合成法制备了一系列组成的YAG∶Ce,RE（RE=Lu,Gd,La）荧光粉。通过XRD、FTIR、SEM、荧光光谱研究了不同煅烧温度、不同共掺杂元素和浓度对荧光粉晶体结构、颗粒形貌及发光性能的影响。结果表明：在煅烧温度900℃时即可制得结晶较好的荧光粉,随煅烧温度的升高,样品的平均颗粒尺寸由50 nm左右逐渐增大到200 nm,发光强度逐渐增强。随离子的半径从La3＋到Gd3＋再到Lu3＋逐渐减小,引起基质相变的取代上限逐渐增大,在仅有50 mol%的La3＋掺杂下,样品的主晶相已经变成LaAlO3;Gd3＋掺量达到90 mol%~99 mol%时,样品主晶相仍为立方的YAG相;而Lu3＋可以完全取代Y3＋而仍然保持立方YAG的石榴石结构不变。当Gd3＋取代Y3＋时,YAG∶Ce3＋的发射光谱红移,未出现GdAlO3前最大红移为21 nm,完全取代后最大红移达33 nm,而Lu3＋全部取代Y3＋时发生24 nm的蓝移。运用晶体场理论和位形坐标模型对此进行了解释。

（Y0.99-xREx）3Al5O12∶Ce0.03（RE=Lu,Gd,La） phosphors were successfully synthesized by sol-gel combustion method using citric acid as chelating agent and fuel.Through the analysis of XRD,FTIR,SEM,and photoluminescence spectrum（PL）,the crystal structure,particle morphology and luminescent properties of YAG∶Ce under different calcination temperatures and RE co-doped concentrations were investigated.The powders with nanocrystalline size were obtained only at 900 ℃.As the calcination temperatures increasing,the average particle size was from 50 nm to 200 nm.With decreasing ionic radius from La3＋,Gd3＋,to Lu3＋,the ceiling concentration leading to phase transformation was gradually increasing.Doped with only 50 mol% of La3＋,to replace Y3＋sites,the main phase of sample had transformed into LaAlO3.While the concentration of Gd3＋,reached 90 mol%-99 mol%,the main phase of sample remained cubic YAG.Furthermore,Y3＋ were completely replaced by Lu3＋,with a cubic YAG.The location of the emission peak of Gd-codoped YAG∶Ce3＋system shifted to the red region,and it had a red shift of 21 nm corresponding to the maximum emission intensity before the appearance of GdAlO3.It reached 33 nm when Y3＋ sites were completely replaced by Gd3＋.Additionally,it had a blue shift of 24 nm when Y3＋ completely replaced by Lu3＋.The model of configuration coordinate and the crystal field theory gave this phenomenon a reasonable explanation.