Pr3+离子激活的钛酸盐基质红光发射材料及其光色的温度敏感特性研究

In spite of its obvious shortcomings, Eu3+ has still been an activation ion in most commercial red-emitting phosphors up to now. Red emission can also be fulfilled through Pr3+ doped in an appropriate host, but the realization of this red emission is greatly dependent on the composition and structure of host compounds. The titanates with specific structure are potential ideal host compounds. Furthermore, the Pr3+-activated red-emitting materials have advantage in comparison with that of Eu3+-doped materials in such aspects as chromaticity coordinates, color purity, fluorescence decay time, cost and so on. Meantime, some titanates show blue to green emission and this host emission usually has different temperature-dependence characteristic in comparison with Pr3+ red emission. As a result, the temperature-sensitive phosphors for temperature detecting can be realized due to different emission color at different temperatures. On the basis of preliminary work, the project will pay effort to the following aspects. 1) In consideration of possible influences of crystal structure of target host compound, coordination surroundings around Pr3+, bond length, effective phonon frequency, coordination number and site symmetry on luminescence as a whole, we will design and prepare undoped ideal titanates and Pr3+-activated phosphors. 2) By measuring the emission, excitation and fluorescence decay spectra of the pure hosts and the Pr3+-doped phosphors, we will understand the dependence of electron transitions of Pr3+ on composition and structure of host compounds. 3) With the help of luminescence spectra at different temperatures, we will investigate the influence of temperature on emission intensities of host and Pr3+. 4) With the experimental results of the effective phonon frequency and concentration-quenching, we will get insight into the influences of effective phonon frequency and doping concentration on the rates of the multiphonon relaxation and phonon-assisted cross-relaxation of Pr3+ 3P0 and 1D2 energy levels, understand the relationship between IVCT (intervalence charge transfer) energy and the quenching of 3P0 state, and clarify the quenching tunnel of Pr3+ 3P0 state in an exact host. 5) Through these efforts, we aspire to find new luminescent materials with strong red emission and emission color tunable phosphors with temperature-sensitive characteristics in a wide temperature range under ultraviolet, visible or low voltage electron beam excitations.

红光发射多通过Eu3+离子实现，但有缺点和局限。Pr3+的红光发射在色坐标、色纯度、衰减时间、成本等方面均有优势，但红光发射的实现强烈依赖基质组成和结构，具有特定结构的钛酸盐是潜在的理想基质。此外，一些钛酸盐基质发射与Pr3+离子红光发射对温度的响应特性不同，据此还可能获得光色随温度改变的温度探测材料。本项目在前期工作基础上，综合考虑目标基质化合物晶体结构、发光中心配位形式、键长、声子频率等因素，设计并合成Pr3+离子激活的理想钛酸盐基质发光材料；认识基质发射及Pr3+的电子跃迁与基质组成和结构的关系；理解温度对基质及Pr3+发射强度的影响；研究声子频率、掺杂浓度与Pr3+离子3P0/1D2能级多声子驰豫、交叉驰豫的关系，分析IVCT对3P0能级的猝灭作用，澄清在特定钛酸盐基质中，3P0能级的猝灭通道；探索不同激发条件下有强红光发射的新发光材料和温度改变时光色可调的温度探测新材料。

项目紧扣申请书和计划书设定的目标实施，研究计划执行情况良好。在前期工作基础上，设计、并通过高温固相反应方法合成了Pr3+离子激活的理想钛酸盐基质La2MgTiO6、层状钙钛矿结构Na2La2Ti3O10和Na2Gd2Ti3O10等发光材料及Pr3+、Sm3+、Tb3+、Dy3+等掺杂的LuNbO4荧光材料。研究了其在激发光谱、发射光谱、时间分辨光谱和荧光衰减等。此外，在项目资助下，还研究了Ce3+、Pr3+、Eu3+、Eu2+、Mn2+、Mn4+等稀土/过渡金属离子掺杂的复合氧化物基质发光材料，在完成该项目目标的基础上，扩大了研究视野，并为下一步研究打下了良好基础。.项目发现了一些有潜在应用价值的新材料，如：温度探测材料La2MgTiO6:Pr3+、Na2Ln2Ti3O10:Pr3+ (Ln = La, Gd)、Ca6BaP4O17:Eu2+、Li4SrCa(SiO4)2:Eu2+、LiY9(SiO4)6O2:Ce3+，X-射线闪烁材料RbBaPO4:Eu2+、Ba2MgSi2O7:Eu2+，高热稳定性红光发射材料BaMgP2O7:Eu2+,Mn2+、Rb2TiF6:Mn4+、Na3TaF8:Mn4+，光色可调的LED发光材料Ba3La(PO4)3:Tb3+,Sm3+等；发表标注基金资助的研究论文30余篇；实施期间，申请国家发明专利8件，其中2件已获授权，获2018年度中国有色金属科学技术奖三等奖(2/8)、2018年度重庆市科学技术奖自然科学三等奖(5/5)、2019年度广东省科学技术奖科技进步奖二等奖(2/10)。