草酸沉淀法制备细颗粒红色荧光粉Y2O3：Eu3+的发光特性

对草酸作为沉淀剂制备的细颗粒红色荧光粉Y₂O₃:Eu³⁺进行结构和发光特性研究,结果表明:其一次粒径为20～30nm,团聚尺寸D₅₀=0.53μm。该荧光粉最大激发峰位于252.2nm,较微米级荧光粉233nm红移了19.2nm;最大的发射峰位于612nm,与微米级的相比几乎没有差别。Eu³⁺离子的掺入构成了发光中心,其最佳掺杂的质量分数为9%,荧光粉发光的猝灭浓度由微米级的6%提高到9%。由于纳米晶存在表面缺陷和悬挂键,其亮度约为微米晶的70%左右,随着团聚尺寸的增加、煅烧温度的提高和助熔剂的加入,荧光粉的发光强度增大。包膜能部分消除表面缺陷和悬挂键,提高发光亮度。荧光粉的色坐标为x=0.6479,y=0.3442。

Luminescent Properties of Small-sized Red Phosphor Y2O3:Eu3+ Synthesized by Oxalic Acid Precipitation Method

Y₂O₃:Eu³⁺ is a red phosphor with good property.It is usually synthesized by high temperature solid state method.The particle size of the phosphor prepared by this method is lager ,so it must be milled when used.The oxalic acid precipitation method was developed to synthesize non-grinded and small-size red phosphor in our experiment.Firstly,the mixture of Y₂O₃ and Eu₂O₃ was dissolved in nitric acid in certain proportion.Secondly,the prepared oxalic acid solution was placed in a reactor and at the same time a little surfactant was added in it.When the reaction temperature was controlled to be certain value,the nitric acid solution of Y,Eu was added.Afterwards the precipitation formed and then washed,filtrated,dried and calcined to become white Y₂O₃:Eu³⁺ power.The Luminescent properties of the phosphor were mainly studied .The result shows that the particle diameter is 20～30nm.The agglomerate size is D₅₀=0.53μm.The particle is fine and the granularity distribution displays a narrow and normal distribution.The maximum excitation spectrum of the phosphor peaks at λ=252.2nm,red shift 19.2nm compared with micro-Y₂O₃:Eu³⁺.The maximum emission spectrum peaks at λ=612nm under 254nm excitation.Compared with the ordinary power of Y₂O₃:Eu³⁺ ,the emission spectrum of the phosphor appears unchangeable.The luminescent intensity increases with growing of agglomerate size.The addition of Eu³⁺ can constitute luminescent centers when Y₂O₃ as basic particle and Eu³⁺as activator in Y₂O₃:Eu³⁺ .The less the amount of the added Eu³⁺ is,the lower the luminescent brightness of the phosphor is.The critical concentration of Eu³⁺ increases from 6% for micro-Y₂O₃:Eu³⁺ to 9% for nano-Y₂O₃:Eu³⁺.The phosphor shows a relative luminescent brightness about 70% of that of the micro-Y₂O₃:Eu³⁺,because of the existence of hanging-bonds and defects on the surface of nano-Y₂O₃:Eu³⁺ particles.The phosphor particle was increased and the defects on the surface of the phosphor was decreased at high temperature,so luminescent brightness of the phosphors was increased.Adding assist melting agent can decrease sintering temperature and increase D₅₀ of the phosphor,and the brightness of the phosphor increased,too.Coating-process on phosphor can dispel defact and increase brightness.The luminescent chromatic coordinate parameters of the phosphor are x=0.6479,y=0.3442 ,which accords with the phosphor.