电子俘获材料CaS∶Eu,Sm光谱特性研究

研究了电子俘获材料CaS∶Eu,Sm多晶粉末的紫外-可见-红外吸收光谱及红外激励光谱.研究结果表明,CaS∶Eu,Sm中主激活剂Eu和辅助激活剂Sm分别以Eu2+离子和Sm3+离子的形式存在；ETM的吸收差谱及红外激励光谱所反映的光谱特性是不同的.紫外-可见光区的吸收差谱给出了ETM光谱存储灵敏度的信息,而红外光谱区的吸收差谱给出了ETM所俘获电子数量的信息及电子陷阱能级的特征（深度和宽度）信息.红外激励光谱则反映了ETM将不同波长的红外激励光的能量转换为特定波长处的红外辐射光能量的光谱转换灵敏度.二者结合起来可以更完整地描述ETM的光谱特性.     

电子俘获型薄膜材料的结构与光学性能

采用电子束沉积技术成功制务了以碱土金属硫化物为基质材料，稀土元素离子作为激活中心的输出红光的红外上转换及光存储薄膜材料ＣａＳ：Ｅｕ，Ｓｍ物相结构测试表明，基片温度和后退火晶化处理对薄膜的晶态有很大影响，在本实验的制备条件下，（２００）面的衍射蜂最强；加硫共蒸或通入少量Ｈ２Ｓ有助于改善ＣａＳ薄膜的化学计量比，光谱测试表明，薄膜材料的光学性能与粉末材料基本相同。     

电子俘获材料CaS∶Eu,Sm光谱特性研究

研究了电子俘获材料CaS∶Eu,Sm多晶粉末的紫外-可见-红外吸收光谱及红外激励光谱.研究结果表明,CaS∶Eu,Sm中主激活剂Eu和辅助激活剂Sm分别以Eu2 离子和Sm3 离子的形式存在;ETM的吸收差谱及红外激励光谱所反映的光谱特性是不同的.紫外-可见光区的吸收差谱给出了ETM光谱存储灵敏度的信息,而红外光谱区的吸收差谱给出了ETM所俘获电子数量的信息及电子陷阱能级的特征(深度和宽度)信息.红外激励光谱则反映了ETM将不同波长的红外激励光的能量转换为特定波长处的红外辐射光能量的光谱转换灵敏度.二者结合起来可以更完整地描述ETM的光谱特性.     

电子俘获材料Eu,Sm：CaS荧光特性的研究

研究了电子俘获材料Eu,Sm:CaS在室温下的荧光激光发谱和荧光辐射谱,荧光激发谱由四个激发带构成,是由Eu^2 的4f^7→4f^55d跃迁和基质吸收所产生的,可见光激光发下的荧光辐射谱是由一个极强的宽带和两个极弱的窄带构成,紫外光激光发下的荧光辐射谱中不仅出现了以上三个辐射带,还出现了七个较强的窄带,这些荧光辐射带分别是由Eu2 的4f^65d→4f^7,Sm^3 的f→f,Eu^3 的f→f跃迁所产生的。研究还发现,当激剂浓度一定时,Eu^2 的辐射带明显比Sm^3 的辐射带强。     

掺稀土离子的电子俘获材料

可利用不等价离子取代法或高能射线辐照法制备电子俘获材料,如长余辉发光材料znO-SiO₂-B₂O₃-MnO、CaS:Eu²⁺,Tm³⁺、CaGa₂S₄:Eu²⁺,Ho³⁺和固体剂量材料Zn_0.96(BO₂)₂:0.04Tb,Sr_0.93Dy_0.07B₄O₇等.利用俘获在缺陷中的电子-空穴对的复合,并把能量传递给Eu²⁺或Mn²⁺等激活离子而产生长余辉发光或热释光.它们将在弱光照明与显示,信息存储和辐射治疗与探测、监控等方面获得应用.     

电子俘获材料的光学性质及光存储机制研究

报道在硫化锶中掺入Ｅｕ、Ｓｍ和Ｃｅ、Ｓｍ两种激活剂的具有良好的光存储功能的新型光子学材料。以紫外到绿光之间不同波长的光写入信息，用近红外光读出，读出信号为橙色或绿色发光。系统的光响应速率小于２０ｎｓ，写／读／擦速度快；光存储机制为电子的俘获和释放，无热效应，比目前的其他光存贮系统更优越。     

用电子俘获材料实现实时图像微分

根据数学形态学的基本思想，采用离焦的卷积光学系统，利用电子俘获材料的饱和特性和图像减法功能实现图像微分，这一方案具有清晰度高、实时性，全并行性的优点，取阀和减法运算都用一片电子俘获薄膜来实现。     

电子俘获材料SrS:Eu,Sm,Er的光谱特性和光存储特性

提出一种Er3+改进的电子俘获光存储材料SrS∶Eu0.002,Sm0.002,Erx,其中,0≤x≤0.006。通过水热反应,研究了不同退火温度对荧光粉晶相形成的影响,以及不同含量的Er3+对荧光粉的发光性质以及光存储特性的影响。结果表明,Er3+的引入导致荧光增强及光存储特性提高。当Er3+的摩尔分数x=0.003时,荧光强度、光激励发光强度及光存储量出现最大值,分别为不含Er3+时的1.9倍、2倍和3.5倍。同时,Er3+的掺入不改变样品的晶体结构和衰减特性。     

制备工艺对电子俘获材料性能的影响

利用等离子体质谱(ICP-MS)技术测试了硫化助熔剂法和稀土直接掺杂工艺合成电子俘获材料的化学计量比,结果表明,采用稀土直接掺杂工艺合成材料的化学计量比更接近设计值;通过分析电子俘获材料的发光机制和光谱测试结果,讨论了制备工艺条件对电子俘获材料中稀土离子化合价的影响.     

用吸收差谱研究电子俘获材料的光激励发光

以SrS:Eu, Sm为例说明可以利用电子俘获材料在光激发前后的吸收谱的差别来获取电子俘获材料光激励发光的信息。电子俘获材料在激发后的吸收光谱同时包含了不同陷阱(杂质)对光激励的吸收情况。因此激发前后的吸收光谱差(吸收差谱)除了能给出与光激励谱相同的信息外,还包含空穴陷阱的激励,光存储总量等信息,因此有助于更全面地了解材料的光激励发光过程。     

存储型上转换发光材料CaS∶Eu,Sm的发光机理研究

采用低温燃烧合成(LCS)法制备了存储型上转换发光材料CaS∶Eu,Sm,并对其上转换发光机理进行了研究.研究表明:样品的激发光谱位于200～600nm之间,紫外或可见光均可有效地激发该材料来完成充能过程,且可见光激发占优势;样品的红外响应光谱范围为800～1600nm,由辅助激活离子Sm所形成的劈裂的深陷阱能级是该材料具有宽频谱红外转换特性的根本原因;样品的热释光谱高温峰值位于351.02℃,计算得到的陷阱能级深度为0.82eV,深度适中,利于激发能的储存和上转换发光的产生.     

存储型上转换发光材料CaS:Eu,Sm的发光机理研究

采用低温燃烧合成(LCS)法制备了存储型上转换发光材料CaS∶Eu,Sm,并对其上转换发光机理进行了研究。研究表明:样品的激发光谱位于200~600nm之间,紫外或可见光均可有效地激发该材料来完成充能过程,且可见光激发占优势;样品的红外响应光谱范围为800~1600nm,由辅助激活离子Sm所形成的劈裂的深陷阱能级是该材料具有宽频谱红外转换特性的根本原因;样品的热释光谱高温峰值位于351.02℃,计算得到的陷阱能级深度为0.82eV,深度适中,利于激发能的储存和上转换发光的产生。     

The study on optically stimulated luminescence dosimeter based on the SrS：Eu,Sm and CaS：Eu,Sm

With the increasing use of nuclear energy, there is a need for a wider range of efficient dosimeters for radiation detection and assessment. There has been a tremendous growth in the development of radiation detectors and devices in the past few decades. In recent years, the development of new materials for radiation dosimetry has progressed significantly. Alkaline earth sulfides （AES） have been known for a long time as excellent and versatile phosphor materials. In the present investigation, a number of phosphor samples such as mono-, binary and ternary sulfides of alkaline earths （II^a-VI^b） have been prepared and their TL properties have been studied with respect to exposure （x-ray） response and fading. In this paper, some results on SrS：Eu, Sm and CaS：Eu, Sm phosphors are presented. A type of novel OSL dosimeter is described. The dosimeter takes advantage of the characteristics of charge trapping materials SrS：Eu, Sm and CaS：Eu, Sm that exhibit optically stimulated luminescence （OSL）. The measuring range of the dosimeter is from 0.01 to 1000 Gy. The OSL dosimeters provide capability for remote monitoring radiation locations which are difficult to access and hazardous. This equipment is relatively simple, small in size and has low power consumption. The device is suitable for space radiation dose exploration. In addition, it also can be used in IC and other radiation occasions and has good prospects.     

Study on relationship of luminescence in CaS:Eu,Sm and dopants concentration

In order to study different characteristic luminescence of Eu²⁺ and Sm³⁺, delayed photoluminescence (DPL) and infrared stimulated luminescence (ISL) spectra of CaS doped with europium and samarium have been investigated. The influence of Eu and Sm concentration on luminescence of Eu²⁺ in photoluminescence (PL) and ISL was respectively studied. It was found that, at low doping levels, PL emission intensity of Eu²⁺ increased linearly with increment of Eu, while decreased linearly with increment of Sm. However, further increment of Eu and Sm in CaS:Eu,Sm could not increase either the luminescent centres of Eu²⁺ or electron trapping sites of Sm³⁺. Different local environment of Eu²⁺ and Sm³⁺ in the lattice position is thought to be the cause of all observed luminescence phenomena. Finally, the maximum emission in ISL was obtained at 1000 ppm europium and 750 ppm samarium.     

Effect of the growth conditions on infrared upconversion efficiency of CaS: Eu, Sm thin films

High-quality electron-trapping thin films CaS: Eu, Sm with red light output have been successfully deposited on quartz and single-crystal silicon substrates by electron beam evaporation (EBE) and radio frequency (RF) magnetron sputtering in vacuum and H₂S partial pressures. Infrared upconversion efficiency of CaS: Eu, Sm thin films under different growth conditions has been investigated by using ultrashort infrared (IR) laser pulse with 20 ps (full width at half-maximum (FWHM)). The results show that upconversion efficiency of CaS: Eu, Sm thin films depends strongly on growth conditions in spite of the existence of “exhaustion” phenomena. Microstructures identified by X-ray diffraction (XRD) indicate that crystallinity of CaS films relies on both substrate materials and growth conditions. The stoichiometric composition of CaS films was measured by secondary-ion mass spectrometry (SIMS). The post-annealing process was found to promote grain growth and activate strong luminescence so that it could obviously improve upconversion efficiency of CaS: Eu, Sm films, even though it had negative influence on transmittance and spatial resolution of these films. Received: 5 June 2000 / Accepted: 7 June 2000 / Published online: 23 August 2000     

CaS∶Eu~(2+),Sm~(3+)的制备与表征

采用湿法工艺在还原气氛下制备了CaS∶Eu2+,Sm3+光存储材料。研究了灼烧温度和灼烧时间对样品性能的影响。XRD图谱表明,样品在700℃—1200℃均形成CaS晶格。光谱分析表明,在紫外光(295nm)激发后,用980nm半导体激光照射样品,具有光激励发光现象,发射光谱峰值波长为649nm。     

Luminescence properties of CaS:Ce, Sm nanophosphors

CaS:Ce, Sm nanophosphors were synthesized via solid state diffusion method. X-Ray diffraction confirmed the cubic crystalline phase of CaS:Ce, Sm nanoparticles. The particle size calculated using Debye-Scherrer formula was found to be 52 nm. The morphological investigations of the nanoparticles were made using TEM and found to have nearly spherical morphology with diameter 45-50 nm, which is in close agreement with the XRD result. The PL emission characteristics of CaS:Ce, Sm as a function of cerium and samarium concentrations have been studied and CaS:Ce_0.6Sm_0.4 system has maximum emission intensity, hence it was opted for further studies. The CaS:Ce_0.6Sm_0.4 system showed independent emission of Sm and Ce when excited at 330 and 450 nm, respectively. To study the energy transfer between cerium and samarium, the CaS:Ce_0.6Sm_0.4 was excited at wavelengths other than the excitation wavelengths of Ce (450 nm) and Sm (330 nm). The existence of Ce emission (at an excitation of 390 nm) even in the absence of Ce excitation band and Sm emission at an excitation of 405 nm, which is the excitation band of Ce, indicates the energy transfer at these two wavelengths. Thermoluminescence characteristics of ⁶⁰Co irradiated CaS:Ce_0.6Sm_0.4 have been investigated for different doses of 0.14-125 Gy. All the glow curves show a single peak at 475 K. With increasing dose, the intensity of this peak increases and a shoulder is formed on the lower temperature side at 415 K at 21 Gy of exposure. CaS:Ce_0.6Sm_0.4 shows almost linear dose dependence up to 125 Gy.     

Different Eu-centres in CaS:Eu, Cl

The EPR and luminescence properties of CaS:Eu,Cl-luminophors with different Cl and Eu concentrations are studied. The Mössbauer effect on ¹⁵¹Eu is measured. Eu as a dopant is shown to form mainly Eu³⁺-centres rather than Eu²⁺-centres. Eu oxidation to Eu³⁺ is due to the formation of V_CaCl_S-associates in the CaS lattice. Besides the Eu²⁺-centres of high symmetry various Eu²⁺-Eu²⁺ pairs are formed and are responsible for a broad structureless EPR spectrum and for an infrared shift of the Eu²⁺ luminescence band.