掺稀土硫酸盐纳米荧光体的制备及光致发光特性的研究

采用液相沉淀法制备了纳米荧光体CaSO4:Eu,CaSO4:Dy,MgSO4:Dy,研究并对比了产品的光致发光性能.光谱测试表明,CaSO4:Eu呈近紫外窄带发射;Dy3 掺杂碱土硫酸盐因基质不同,发射带有所不同.以CaSO4为基质,Dy3 占据高对称的格位,具有反演对称中心,发射光谱以蓝光发射为主.以MgSO4为基质,Dy3 占据低对称的格位,无反演中心,发射光谱以黄橙光发射为主.结果证明,所合成纳米荧光体表现出优异的发光特性.     

钬掺杂对SrAl2O4:Eu2+,Dy3+发光性能的影响

首次研究了Ho3+掺杂对SrAl2O4:Eu2+,Dy3+发光性能的影响.采用燃烧合成方法,在600℃条件下,合成Ho3+掺杂的SrAl2O4:Eu2+,Dy3+新型长余辉光致发光材料.X射线衍射分析结果表明,合成的样品为单相SrAl2O4单斜晶系磷石英结构.光致发光光谱测量显示,合成样品的发射光谱是连续宽带谱,峰值位于510nm左右,激发光谱是单峰且峰值位于356nm的连续宽带谱.利用单光子计数系统测量了材料的余辉衰减曲线,结果显示Ho3+的适量掺杂可以明显提高铝酸锶的初始发光亮度.当Ho3+的掺入摩尔比例为0.005时,初始亮度是不掺杂Ho3+时的两倍多.对初始亮度增强的机理做了初步的探讨.     

碱土金属长余辉材料的耐酸碱性研究

分别对发光性能最好的铝酸盐基质长余辉材料SrAl2O4∶Eu2+,Dy3+与硅酸盐基质长余辉材料Sr2MgSi2O7∶Eu2+,Dy3+进行酸、碱处理(以HNO3和NaOH为例),研究其耐酸碱性能。XRD、SEM、激发光谱、发射光谱以及余辉特性测试的结果表明:SrAl2O4∶Eu2+,Dy3+及Sr2MgSi2O7∶Eu2+,Dy3+经酸、碱处理后物相发生了部分改变,其激发与发射光谱的强度随着酸碱度的增大而降低,但峰形与峰位没有改变;SrAl2O4∶Eu2+,Dy3+经酸碱处理后表面变得更不平整,棱角变得不明显;SrAl2O4∶Eu2+,Dy3+经酸处理后的初始亮度为未处理时的39.2%,经碱处理后的初始亮度为未处理时的14.0%;Sr2MgSi2O7∶Eu2+,Dy3+经酸碱处理后晶体的结构、形貌、表面及余辉衰减情况基本无变化。     

水热-均匀沉淀法制备亚微米长余辉发光材料SrAl_2O_4∶Eu,Dy

采用水热-均匀沉淀法,以尿素为沉淀剂,在聚四氟乙烯低温反应釜中160℃水热,在较低的煅烧温度下制备了亚微米级长余辉发光材料Sr0.97Al2O4∶Eu0.01,Dy0.02。XRD结果表明,在1000℃煅烧4h能得到单相的SrAl2O4∶Eu,Dy,SEM测试显示SrAl2O4∶Eu2+,Dy3+发光材料为球状形貌,粒径大小约为200～500nm,激发和发射光谱结果表明,随着煅烧温度升高,SrAl2O4∶Eu2+,Dy3+的发光强度也随之增强,其激发光谱峰值位于360nm,发射光谱峰值位于513nm,SrAl2O4∶Eu2+,Dy3+在1100℃煅烧后的余辉衰减时间比1000℃煅烧后显著提高,其热释光谱峰值在80～90℃。     

白光LED用全色荧光粉BaMgSiO4:Eu2+,Mn2+的光谱性质

采用高温固相法首次合成了由Eu2+和Mn2+共激活的硅酸镁钡BaMgSiO4全色荧光粉.BaMgSiO4的晶格结构中含有丰富的阳离子格位,有六配位的Ba(Ⅰ)、九配位的Ba(Ⅱ)和Ba(Ⅲ)以及四配位的Mg,为Eu2+和Mn2+提供了不同环境的占据格位.光谱测试显示BaMgSiO4:Eu2+,Mn2+的发射光谱中有3个发射峰,分别是440nm、510nm、620nm,是合成白光较理想的三基色波带;激发光谱呈宽波带,在300～420nm之间均有较强的吸收,能与紫光InGaN芯片匹配,适用于白光LED.     

HA:RE(RE=Eu3+、Tb3+)纳米棒的制备与细胞毒性研究

采用EDTA为模板,以CaCO3、NH4H2PO4、Eu2O3、Tb7O4、HNO3为原料,用NH3 H2O调节pH值,成功制备了掺铕羟基磷灰石(HA:Eu3+)及掺铽羟基磷灰石(HA:Tb3+)纳米棒,并采用XRD、场发射环境扫描电子显微镜、荧光光谱、酶联监测仪等对其荧光及细胞毒性进行了研究。结果表明:制备的HA:Eu3+纳米棒最强发射峰位于617 nm处,发射出明亮的红光;制备的HA:Tb3+纳米棒最强发射峰位于544 nm处,发射出明亮的绿光;细胞毒性研究表明HA:RE(RE=Eu3+、Tb3+)纳米棒是一种良好的生物示踪材料。     

长余辉发光材料Sr4Al14O25:Eu2+,Dy3+的制备

采用化学沉淀法制备了Sr4Al14O25:Eu2 ,Dy3 蓝绿色长余辉发光粉.通过XRD分析表明:经1100℃和1200℃煅烧制得的发光粉均为单一的Sr4Al14O25晶相,不含其它任何杂相,同时研究了硼酸的加入量对发光粉的物相变化和发射光谱的影响,通过场发射扫描电子显微镜分析了粉体的形貌和粒径.     

红色荧光粉BaZn2(PO4)2:Eu3+的制备及其光谱特性

采用高温固相法制备了BaZn2(PO4)2:Eu3+红色荧光材料.测量了BaZn2(PO4)2:Eu3+材料的激发与发射光谱,激发峰位于360-400nm之间,发射光谱主峰位于595nm处.研究了BaZn2(PO4)2:Eu3+材料在595nm的主发射峰强度随Eu3+浓度的变化,发射峰强度先随Eu3+浓度的增加而增大;...     

Eu2+在KNaCa2（PO4）2中的发光及晶体学格位

采用高温固相法制备了KNaCa2(PO4)2:Eu2+蓝色荧光粉,并研究了材料的发光特性.在400 nm近紫外光激发下,材料呈非对称的单峰发射,主峰位于470 nm.监测470 nm发射峰,对应的激发光谱覆盖200~450 nm,主峰位于400 nm,说明材料能够很好的吸收紫外?近紫外光,发射蓝色光.利用van Uitert公式计算了Eu2+取代KNaCa2(PO4)2中Ca2+时所占晶体学格位,得出461和502 nm发射分别归属于八配位和六配位的Eu2+发射.研究了Eu2+掺杂浓度对KNaCa2(PO4)2:Eu2+材料发射强度的影响,结果显示Eu2+的最佳掺杂浓度为1mol%,利用Dexter理论得出其浓度猝灭机理为电偶极?电偶极相互作用.     

SrAl2O4:Eu2+发光材料的合成工艺研究

以碳粉作还原剂,SrCO3、Al2O3、Eu2O3为原料,在还原气氛下采用固相烧结法合成了SrAl2O4:Eu2+发光材料;对合成物进行了X射线粉晶衍射、荧光光谱测定;并初步探讨了Eu2+的含量、制备工艺过程中的焙烧温度、保温时间、冷却方式等因素对合成样品发光性能的影响.     

PMMA/硅铝包覆铝酸锶复合发光材料的制备和发光性能

采用原位乳液聚合法制备了聚甲基丙烯酸甲酯(PMMA)/硅铝包覆(SrAl2O4:Eu,Dy)复合发光材料。通过傅立叶变换红外光谱(FT-IR)和热失重(TGA)测定,研究了复合发光材料的结构,结果表明,复合发光材料中聚合物分子与硅铝包覆(SrAl2O4:Eu,Dy)之间是通过键合的方式结合;通过荧光光谱和发光亮度测试,研究了复合发光材料的发光特性和余辉性能,结果表明,在硅铝包覆(SrAl2O4:Eu,Dy)表面共价结合上PMMA后仍能保持SrAl2O4:Eu,Dy原有的发光性能。     

SrAl2O4:Eu2+,Dy3+光致发光搪瓷涂层的制备

稀土Eu^2 激活的铝酸盐发光材料是近年来新发展起来的新型长余辉光致发光材料，由于其发光亮度和发光余辉比传统的硫化物高许多，且无毒，无放射性，因而引起广泛关注，采用高温固相反应法制备了SrAl2O4:Eu^2 ,Dy^3 发光材料，并利用SrAl2O4:Eu^2 ,Dy^3 发光材料，参考普通搪瓷的制备工艺，制得了性能稳定的光致发光搪瓷涂层，余辉时间长达12h以上，这种发光搪瓷涂层可用于制造广告牌，交通标牌和建筑物标识牌等，在许多领域有应用前景。     

Electron spin resonance evaluation of pure CaSO4 and as a phosphor doped with P and Dy

Polycrystalline CaSO4 powder, doped with different elements but mainly rare earths, is one of the most interesting thermoluminescent (TL) materials. Although many electron spin resonance (ESR) analyses have been reported for these materials few studies have been published about the potential of CaSO4 for ESR dosimetry; almost all studies used CaSO4:Dy with a very low Dy concentration as the material for TL measurements. Pure CaSO4 from Merck was used to prepare CaSO4:Dy and CaSO4:P:Dy with different Dy concentrations. Samples were annealed at 600 degrees C for 1 h before irradiation in a Gammacell 220 irradiator with a 60Co gamma source at a dose rate of 100 Gy x min(-1). The ESR spectra of the pure CaSO4 and CaSO4 doped with P and Dy show the lines usually observed with these types of material, with the factor g around 2.036 and an intense line at g = 2.0011 found only in the pure material. This line, probably an axial SO4-, grows linearly with absorbed dose until 1.0 kGy and shows good stability with time. The line should be stabilized by matrix impurities because it can be removed by a simple treatment with hot sulphuric acid.     

Mechano and thermoluminescence of gamma-irradiated CaSO4:Dy phosphor

In order to have a better idea of the interaction of the defect centres produced by y-irradiation with dislocation in the processes of deformation destruction, mechanoluminescence (ML) and thermoluminescence (TL) of gamma-irradiated CaSO4:Dy, these phosphors have been investigated. CaSO4:Dy phosphors were prepared by dissolving CaSO4.2H2O in sulphuric acid and evaporating the excess acid around 300 degrees C. ML was excited impulsively by dropping a load on to the sample. Two peaks have been observed in the ML intensity against time curve. The total light output, i.e. integrated ML intensity, increases with concentration of dopant, strain rate and with irradiation doses. The TL glow curves of CaSO4:Dy phosphors at different concentrations of dopant and irradiation doses were also recorded. Studies of the influence of post-irradiation annealing on the ML of CaSO4:Dy show that with the removal of the TL dosemetric peak (approximately 210 degrees C) the ML intensity decreases markedly. A spectroscopic study of ML and TL has also been carried out to elucidate the mechanism of ML. Correlation between ML and TL has also been found.     

Thermoluminescence characteristics of teflon embedded CaSO4:Dy TLD

The Korea Atomic Energy Research Institute (KAERI) is manufacturing CaSO4:Dy Teflon TL pellets which have more sensitivity and stability than commercial TLD. A method is presented of preparing the CaSO4:Dy phosphor-embedded Teflon powder, which is then compressed to a thin pellet form used as the TLD element. Investigations are made to determine optimum preparation conditions and dosimetric characteristics of the CaSO4:Dy Teflon pellet such as the sensitivity, energy response, dose response, fading, re-usability, and lowest level of detection. The results show that the sensitivity of the CaSO4:Dy pellet is 2 times higher than that of the commercial Teledyne CaSO4:Dy pellet. A dose-response was observed to be linear in the range from 10(-5) to 10 Gy. The relative energy response in the low energy region was 9.6 (normalised to the 137Cs gamma source), and the fading rate was about 10% for five months. The re-usability was estimated to be more than 60 cycles, and the low level of detection dose was 22 microGy. From the results, the CaSO4:Dy pellet developed in KAERI can be successfully used in personal dosemeters through appropriate filter design for compensating the energy response.     

Development of a TL detector for neutron measurement by CaSO4:Dy phosphors

Personal neutron dosimetry is quite a difficult area because a neutron is always accompanied with gamma radiation, which is required of a capability for mixed field dosimetry. CaSO4:Dy phosphor is known to have a very high sensitivity to gamma radiation, but the neutron capture cross section of the constituents of CaSO4:Dy are so small that the interactions between the thermal neutron and the phosphor are rare. One method to improve the neutron interaction is by introducing an impurity ion with a large thermal neutron captures cross section into the phosphor to act as a neutron target centre such as 6Li. In neutron-gamma mixed radiation fields, if two detectors for the 6Li-7Li compounds embedded CaSO4:Dy thermoluminescent (TL) pellets are used, a 6Li-compound embedded pellet can detect the neutron and gamma radiations together, and the other pellet can only detect the gamma radiation. Recently, the Korea Atomic Energy Research Institute (KAERI) has developed a new type of CaSO4:Dy TL materials embedded with phosphorous (KCT-300) to detect beta and gamma radiation with a very high sensitivity. This paper presents the development of CaSO4:Dy TL pellets embedded with 6Li compound for a thermal neutron measurement, and the detection method of the neutron and gamma dose in mixed fields with CaSO4:Dy TL pellets embedded with a 6Li compound (KCT-306) and CaSO4:Dy TL pellets embedded with a 7Li compound (KCT-307) is introduced. The net neutron sensitivity of CaSO4:Dy TL pellets embedded with 6Li compound developed in this study is about two times higher than that of the TLD-600 (Harshaw Chemical) dosemeter which is available commercially.     

CaSO4晶须在PVC复合体系中的应用研究

用红外分光光度计、X射线粉末衍射仪和光学显微镜对CaSO4晶须A、B和C进行结构表征和形貌观察。结果表明,晶须A、B和C的长径比为5.2、9.1和3.3,经改性的晶须B晶体结构规整,缺陷最少。分别制备了以3种晶须为补强材料的PVC复合体系,讨论了晶须结构对CaSO4晶须/PVC复合体系的力学性能、绝缘电阻和200℃静态热稳定时间的影响。用光学显微镜、扫描电镜和热重分析仪分析了晶须在复合体系中的分散形态和体系的热稳定性。研究发现,长晶须A和B对复合材料的增强增韧和热稳定作用好于短晶须C、CaCO3和气相法白炭黑。经改性的晶须B与PVC树脂有良好的相容性和界面结构,体系的拉伸强度、断裂伸长率和热稳定时间分别达到了23.20MPa、380.85%和95min,可以看出,长径比大,结晶性良好,且经过改性的CaSO4晶须能明显提高复合体系的综合性能。     

Defect centres and thermoluminescence in CaSO4:Dy,Ag phosphor

The defect centres formed in the TL phosphor CaSO4:Dy,Ag are studied using the technique of Electron Spin Resonance. The Ag co-doped phosphor exhibits three glow peaks around 130, 220 and 375 degrees C in contrast with the two glow peaks observed in the CaSO4:Dy phosphor at 130 and 220 degrees C at a gamma ray dose of 1Gy. ESR studies show that the additional peak at 375 degrees C correlates with a Ag2+ centre formed due to gamma irradiation and observable only below -170 degrees C. The Ag2+ centre is characterised by an axial g-tensor with principal values g(parallel) = 2.38 and g(perpendicular) = 2.41. ESR studies further indicate that the precursor to a centre observable at low temperature (-170 degrees C) appears to act as the recombination centre for the TL peak at 375 degrees C; this radical is characterised by the g-values g(parallel) = 2.0023 and g(perpendicular) = 2.0038 and is assigned to SO3- radical. It is observed that there is more incorporation of Ag in the CaSO4:Dy system as compared with that in pure CaSO4 system.     

EVA-g-MAH对CaSO_4晶须/尼龙6复合材料性能的影响

采用马来酸酐接枝乙烯-醋酸乙烯酯共聚物(EVA-g-MAH)对CaSO_4晶须/尼龙6(CaSO_(4W)/PA6)增韧改性。通过双螺杆挤出机制备了CaSO_(4W)/PA6二元、CaSO_(4W)-(EVA-g-MAH)/PA6三元复合材料,用SEM、DSC、XRD等观察和表征了形貌、结构和结晶参数,并测试了力学性能。研究表明:添加少量CaSO_(4W)可提高PA6的结晶速率,而高含量CaSO_(4W)导致PA6结晶速率降低,促进γ晶型形成。添加10%(质量分数)CaSO_(4W)可同时提高PA6的刚性和韧性;添加30%CaSO_(4W)可进一步提高PA6的刚性,但PA6的韧性明显降低。添加2.5%和5%(质量分数)EVA-g-MAH,能使30%CaSO_(4W)-(EVA-g-MAH)/PA6的抗冲击强度分别提高25.0%和76.7%,并使其具有较高韧性。冲击强度的提高主要源于EVA-g-MAH所产生的能量耗散、改善应力的有效传递、增强CaSO_(4W)与PA6的界面以及EVA-g-MAH/PA6共混体系较好的相容性。