Persistent luminescence dosimetric properties of UV-irradiated SrAl2O4:Eu, Dy phosphor

Current radiation dosimetry methods involve the release of trapped charge carriers in the form of electrons-holes pairs generated by irradiation exposure of the dosimetric materials. Thermal and optical stimulations of the irradiated material freed the trapped charges that eventually recombine with interband centers producing the emission of light. The integrated intensity of the emitted light is proportional to the radiation dose exposure. In this work, we present an UV radiation dosimetry technique based on the characteristic persistence luminescence (PLUM) 4f⁶5d¹→4f⁷ electronic transition of Eu²⁺ ions in SrAl₂O₄:Eu²⁺, Dy³⁺. The dose assessment is carried out by measuring the PLUM signal integrated during a certain time. The PLUM performance of SrAl₂O₄:Eu²⁺, Dy³⁺ phosphor exhibited a linear behavior for the first 50 s of UV irradiation. For higher UV time exposure the behavior is sublinear with no apparent saturation during a 10 min period. The PLUM dosimetry response was performed at 400 nm that corresponds to the main band component of the PLUM excitation spectrum in the 250-500 nm range. The main advantage of a dosimeter device based on the PLUM of SrAl₂O₄:Eu²⁺, Dy³⁺ is that neither thermal nor optical stimulation is required, avoiding the need of cumbersome electronic photo/thermal stimulation equipment. Due to the highly efficient 250-500 nm PLUM response of SrAl₂O₄:Eu²⁺, Dy³⁺, it could have potential application as UV radiation dosimeter in the UV range of grate human health concerns caused by UV solar radiation.     

MgAl2O4尖晶石的合成及作为甲烷部分氧化反应的良好催化剂载体

γ-Al2O3 has been intensively studied as a catalyst support in alkane conversion due to its large surface area. However, it is susceptible to crystal phase transition and favors catalyst sintering while the operaing temperature is higher than 700℃. Therefore, its application in industrial reactions is limited.     

NiO对镁铝尖晶石反应烧结性能的影响

本文以高纯电熔镁砂和煅烧活性氧化铝粉为原料,以氧化亚镍(NiO)为添加剂,通过传统固相烧结法制备镁铝尖晶石材料。将MgO和Al₂O₃粉按理论摩尔比1∶1进行配料,在体系中分别引入质量分数为0%、0.5%、1.0%、1.5%、2.0%的NiO。利用X射线衍射(XRD)仪、扫描电子显微镜(SEM)和能谱仪(EDS)对烧结后试样进行分析,研究了NiO的添加对MgAl₂O₄材料烧结性能、物相组成及显微结构的影响。结果表明:引入适量的NiO可以显著促进MgAl₂O₄相的形成以及晶粒的发育长大;在1 600 ℃时,当NiO含量低于1.5%时,NiO能完全溶入MgAl₂O₄晶格并优先取代Al³⁺,提高了MgAl₂O₄晶体内部的缺陷浓度,活化了晶格,从而促进MgAl₂O₄的烧结。当NiO含量高于1.5%时,其内部开始出现较多第二相NiO,阻碍了物质的迁移和传输,反而不利于MgAl₂O₄烧结性能的提高。     

Yb^3+含量对掺Er^3+铝酸盐玻璃光谱性质的影响

采用高温熔融法制备百分比为(100-x)(23.6Al2O3-53CaO-7.7BaO-2.1Na2O-10.3Ga2O3-3.1B2O-0.2Er2O3)-xYb2O3(x=0,0.9,1.9,2.8,3.6,4.5)的铝酸盐玻璃。应用差示扫描量热法、吸收光谱、荧光光谱、红外光谱以及拉曼光谱等检测手段,系统研究了不同Yb^3+离子引入量对玻璃的物性、热稳定性、Er^3+离子光谱性质和结构的影响。结果表明,Yb2O3含量越高,玻璃的密度和折射率越大,抗析晶能力有所增强。随着Yb2O3的增加,玻璃在976 nm吸收系数增大,对应于Er^3+离子的2H11/2→4I15/2、4S3/2→4I15/2以及4F9/2→4I15/2跃迁的527,549,666 nm的上转换发光、红光与绿光发光强度比以及对应于4I13/2→4I15/2的1.53μm近红外荧光强度明显增加。当Yb2O3浓度为3.6%时,铝酸盐玻璃样品在近红外1.53μm荧光最强,此时Yb^3+→Er^3+正向能量传递效率η1最大,约为82.9%。该系列铝酸盐玻璃中Er3+离子1.53μm最大发射截面为0.77×10^-20 cm^2,荧光半高宽最大值为39.4 nm,荧光寿命最大值为4.46 ms。     

SB粉水热分解铝酸钠溶液制取大孔容高比表面拟薄水铝石

 以德国Condea公司用有机醇铝法生产的拟薄水铝石SB粉为晶种,采用水热分解铝酸钠溶液结合乙醇分散洗涤种分产物的方法制得了大孔容高比表面拟薄水铝石. 研究了铝酸钠溶液组成(Al2O3浓度和苛化系数)以及晶种循环使用次数等条件对溶液分解率、 Na2O析出率和种分产物孔体积、孔径分布、比表面积以及钠含量等物化性质的影响. 研究表明, 在晶种比为1.0, 温度为125 ℃的条件下用SB粉分解铝酸钠溶液(Al2O3含量为100～140 g/L, 苛化系数为1.30～1.45), 3 h后溶液分解率可达30%左右,而SB粉连续循环使用3次所得产物的孔容和比表面积分别达到0.84 cm3/g和213.6 m2/g, Na2O含量在0.3%以下,部分性质甚至超过了SB粉的技术指标. 该方法为从廉价的铝酸钠溶液制备高附加值的拟薄水铝石提供了一条新的可供选择的路径.     

Influence of Eu, Dy co-doped strontium aluminate composition on mechanoluminescence intensity

We have investigated the mechanoluminescence (ML) of Eu,Dy co-doped strontium aluminates. The SrAl₂O₄ and Sr₃Al₂O₆ indicate high ML intensity, which is clearly visible to the naked eye in the air. SrAl₂O₄:Eu,Dy shows the highest ML intensity and has many filled traps, high quantum efficiency and moderate stiffness. On the other hand, Sr₃Al₂O₆:Eu,Dy does not have many filled traps and high relative quantum efficiency, but Sr₃Al₂O₆:Eu,Dy shows relatively high ML intensity. Sr₃Al₂O₆:Eu,Dy indicates low stiffness. SrAl₄O₇:Eu,Dy has many filled traps and high relative quantum efficiency, but SrAl₄O₇:Eu,Dy shows very small ml intensity. SrAl₄O₇:Eu,Dy indicates high stiffness. This suggests that the stiffness is an important factor for the ML intensity of the Eu,Dy co-doped strontium aluminate system.     

掺杂Eu2+的新型锶铝复合硫氧化物红色发光材料

合成了掺杂Eu2+的新型锶铝复合硫氧化物红色发光材料Sr5Al2O7S∶Eu。用粉末X射线衍射法表征了其晶体结构,计算的晶胞参数为:单斜晶系,a=0.90748(41)nm,b=0.71029(25)nm,c=0.63021(26)nm,β=103.588(41)°,V=0.39485(23)nm。研究了其激发光谱、发射光谱和余辉光谱。发射光谱峰值位于586nm处,半宽度为50nm;激发带主要在可见区,峰值位于500nm处。讨论了Eu的添加量、基质组成、S的含量等与荧光强度的关系。     

锶铝比对稀土掺杂铝酸锶物相及发光性能的影响

用拟薄水铝石溶胶凝胶法成功制备了SrAl2O4：Eu^2 ，Dy^3 长余辉发光材料，样品无需球磨。XRD结果表明：当锶铝摩尔比Sr／Al＞0．3时，发光基质主相为SrAl2O4，杂质相为Sr4Al2O7，Sr／Al比值继续降低至0．25，发光相则以Sr4Al14O25为主，此时杂质相中含有Sr4Al2O7和Dy4Al2O9。Sr4Al2O7相对SrAl2O4：Eu^3 ，Dy^3 的发光性能影响很大，而对Sr4Al14O25：Eu^2 ，Dy^3 的发光性能影响不大。Dy4Al2O9对SrAl2O4和Sr4Al14O25发光主相的发光性能影响都不大。光谱检测结果表明SrAl2O4：Eu^2 ，Dy^3 发光光谱是中心位于520nm的带状谱。余辉检测结果表明发光主相为SrAl2O4和Sr4Al14O25时，光衰曲线符合I=ct^-n规律，n值分别为n=1．081和n=1．079。     

Comparison Between Sol-Gel,Coprecipitation and Wet Mixing Synthesis of ZnAl2O4

ZnAl₂O₄ was prepared by hydrolyzing a mixture of aluminum alkoxide with zinc nitrate dissolved in hexylene glycol and calcining at 800°C. The results are compared with those obtained by wet mixing and coprecipitation. The sol-gel method produces solids whose surface areas and pore volumes are 100% larger and with a more homogeneous pore size distribution.     

Unusual Luminescence of Ca8[Al12O24]（WO4）2： Tb^3＋

The luminescence properties of aluminate sodalite Ca8[Al12024](WO4)2 (CAW) undoped and doped with Th^3 are reported and discussed. At room temperature the emission of tetrahedral WO4^2- in CAW showed an abnormally small Stokes shift (9060 cm^-1), which is related to the crystal structure of CAW. A strong absorption band in the excitation spectrum of the Th^3 -activated CAW is ascribed to the absorption of the charge transfer state Th^4 -W^5 , into which the excitation resulted in the efficient emission from the ^5D4 level of Tb^3 , but not from the ^5D3 level.