Ca_3La(BO_3)_3∶Tb^(3+)的合成与发光性质

Synthesis and Luminescent Properties of Ca_3La(BO_3)_3 ∶Tb^(3+)Phosphor

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L i2CO3、敏化剂Ce3+离子的加入对荧光粉发光强度的影响。

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 greenphotolumineseenee material, Ca3La（ BO3 ）3： Tb^3^＋ was synthesized by high temperature solid state reaction at a weak reduetive 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 4μm. Excitation and emission spectrum of the Ca3La（ BO3 ） 3：Th^3^＋ and Ca3La（ BO3 ）3： Th3^＋, Ce3^＋ phosphors were measured by the fluorospectrophotometer at room temperature. In analysis of the emission spectrum for Ca3La（ BO3 ）3： Th3^＋ 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 Ca3 La（ BO3 ） 3：Th3 ＋ powder changed along with different concentrations of Th3^＋ ions, and the optimum concentration of Th3^＋ in Ca3 La（ BO3 ）3 is x （Th） = 0.25. According to the dependence of the concentration of Th3^＋ in Ca3La（ BO3 ）3 under the excitation of 251 nm, it was confirmed that the mechanism of concentration selfquenching of Th3^＋ 5 D4→ 7^F5 transition is electric dipole-dipole interaction. The influence of Ce3^＋ on the emission intensity of Th^3＋ was also investigated, after adding low concentration of Ce3^＋ to the system of Ca3 La（ BO3 ） 3 ： Th^3＋, the luminescence intensity increased only slightly, so Ce3^＋ may not be a good sensitizer to Th3^＋ in Ca3La（BO3）3. In addition, it has been confirmed that when a flux, Li2CO3, was added, the 549nm emission corresponding to 5^D4→7^F5 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 Ca3 La （ BO3 ） 3 ： Th^3 ＋ 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 fuorescent lamp.