Ca3La(BO3)3：Tb3+的合成与发光性质

高温固相反应法合成了Ca₃La(BO₃)₃:Tb³⁺光致发光材料。利用扫描电镜和激光衍射分析仪测定了样品的晶粒形貌及粒径大小分布,利用荧光分光光度计研究了Ca₃La(BO₃)₃:Tb³⁺的光致发光特性。确定了在Ca₃La(BO₃)₃基质中Tb³⁺离子浓度对其发光强度的影响及其自身浓度猝灭机理;探讨了助熔剂Li₂CO₃、敏化剂Ce³⁺离子的加入对荧光粉发光强度的影响。

Synthesis and Luminescent Properties of Ca3La ( BO3 ) 3:Tb3 + Phosphor

For many years,the borate luminescence materials have been paid much attention owing to their properties of low preparation temperature and high luminescent efficiency.In order to search for the new green-photoluminescence material,Ca₃La(BO₃)₃:Tb³⁺was synthesized by high temperature solid state reaction at a weak reductive atmosphere which was made by the active carbon powder.The samples had been characterized by scanning electron microscopy(SEM),laser-diffraction size analyzer and fluorospectrophotometer.The results showed that most of the crystals were cylindric and the(average) size of the crystals was about 41 μm.Excitation and emission spectrum of the Ca₃La(BO₃)₃:Tb³⁺and Ca₃La(BO₃)₃:Tb³⁺,Ce³⁺ phosphors were measured by the fluorospectrophotometer at room temperature.In analysis of the emission spectrum for Ca₃La(BO₃)₃:Tb³⁺under 254 nm excitation at room temperature,there are four main emission peaks at 496,549,594,628 nm,among which the intensity of the 549 nm line is the highest.They belonged to the characteristic emission of Tb³⁺ ions.Besides,the luminescent intensity of the Ca₃La(BO₃)₃:Tb³⁺powder changed along with different concentrations of Tb³⁺ ions,and the optimum concentration of Tb³⁺ in Ca₃La(BO₃)₃ is x(Tb)=0.25.According to the dependence of the concentration of Tb³⁺ in Ca₃La(BO₃)₃ under the excitation of 251 nm,it was confirmed that the mechanism of concentration selfquenching of Tb^{3+ 5}D₄→ ⁷F₅ transition is electric dipole-dipole interaction.The influence of Ce³⁺ on the emission intensity of Tb³⁺ was also investigated,after adding low concentration of Ce³⁺ to the system of Ca₃La-(BO₃)₃:Tb³⁺,the luminescence intensity increased only slightly,so Ce³⁺ may not be a good sensitizer to Tb³⁺ in Ca₃La(BO₃)₃.In addition,it has been confirmed that when a flux,Li₂CO₃,was added,the 549nm emission corresponding to ⁵D₄→⁷F₅ transition was intensified greatly.Ca₃La(BO₃)₃:Tb³⁺ phosphor could absorb ultraviolet radiation and emit green light.Compared with the former results of other borate luminescent materials,when Ca₃La(BO₃)₃:Tb³⁺ phosphor was excited by 254 nm UV light,stable and much stronger green light could be emitted,so it is promising to apply in the production of green fluorescent lamp.