共沉淀法制备Y2O2S：Eu3+,Mg2+,Ti4+红色长余辉材料

用共沉淀法制备了Y₂O₂S:Eu³⁺,Mg²⁺,Ti⁴⁺红色长余辉材料。测量了材料的电子显微形貌、晶体结构和发射光谱。通过与固相法制备的Y₂O₂S:Eu³⁺,Mg²⁺,Ti⁴⁺长余辉材料比较,发现两种方法都可以制备粒度基本相同的纯相Y₂O₂S基质晶体,但共沉淀法样品的颗粒结构更松散。研究了Eu³⁺浓度对两种方法制备样品的谱线发射强度的影响,通过比较共沉淀法和高温固相法制备的样品中Eu³⁺的⁵D₁→⁷F₃较高能级跃迁的587.6nm谱线强度随Eu³⁺浓度的变化,发现共沉淀法更有利于Eu³⁺均匀进入Y₂O₂S基质晶格而形成有效的发光中心。

Preparation of a Red Y2O2S: Eu3 +, Mg2 +, Ti4 + by the Coprecipitation Synthesis Method

A red Y₂O₂S:Eu³⁺,Mg²⁺,Ti⁴⁺ phosphor is synthesized by co-precipitation method using the metal oxide,nitric acid and oxalic acid.Nitric acid is used as a solvent to dissolve the raw materials and then form the nitrate solution,while the oxalic acid is used to form precipitation.Since all of the raw materials are mixed at the molecular level in solution,a highly uniform product is achieved.The morphology and crystal structure of synthesized phosphors is investigated by the SEM patterns and the XRD patterns.The SEM patterns analysis showed that the phosphors prepared by co-precipitation method have very relaxing structure with the particle size of about 5.0 μm.This is due to the realization of the material mixture in molecule scales during the doping process of co-precipitation method.The X-ray diffraction analysis showed that XRD pattern of the sample is coincident with the JCPDS Card(No.24-1424) and the sample has crystal structure of Y₂O₂S,which belongs to hexagonal and the crystal lattice constant is as follows: a₀=0.3784 nm,c₀=0.6589 nm.It indicated that the crystal structure hasn’t change with the doping of Eu³⁺,Mg²⁺ and Ti⁴⁺.The emission intensity of the samples with various concentration of Eu³⁺,prepared by the co-precipitation and solid-state method,are compared with each other.When concentration quenching of Eu³⁺ appears,the peak of radioactive spectrum rooting in high excited state of Eu³⁺ vanishes.So we can analyze qualitatively about the amount of Eu³⁺ admitted to enter the crystal lattice through comparing the change of I_587.6/I_627.0 when I_λ is defined as the intensity of emission peak located at wavelength λ.The result shows that I_587.6/I_627.0 of the phosphor prepared by solid-state method obviously decreases with the increasing of concentration of Eu³⁺,while it is steady with co-precipitation method.So the co-precipitation synthesis method can make the Eu³⁺ enter into Y₂O₂S host more easily and form more effective luminescent centers than that synthesed by solid-state method.