Simulation on function mechanism of T1(Al2CuLi) precipitate in localized corrosion of Al-Cu-Li alloys

To clarify the corrosion mechanism associated with the precipitate of Tl(Al₂CuLi) in Al-Li alloys, the simulated bulk precipitate of T1 was fabricated through melting and casting. Its electrochemical behavior and coupling behavior with (Al) in 3.5% NaCl solution were investigated. Meanwhile, the simulated Al alloy containing T1 particle was prepared and its corrosion morphology was observed. The results show that there exists a dynamic conversion corrosion mechanism associated with the precipitate of T1. At the beginning, the precipitate of T1 is anodic to the alloy base and corrosion occurs on its surface. However, during its corrosion process, its potential moves to a positive direction with immersion time increasing, due to the preferential dissolution of Li and the enrichment of Cu. As a result, the corroded T1 becomes cathodic to the alloy base at a later stage, leading to the anodic dissolution and corrosion of the alloy base at its adjacent periphery. It is suggested that the localized corrosion associated with the precipitate of T1 in Al-Li alloys is caused by the alternate anodic dissolution of the T1 precipitate and the alloy base at its adjacent periphery.     

APPLICABILITY OF QUASICHEMICAL MODEL FOR SOME LIQUID ALLOYS WITH STRONG-INTERACTED COMPONENTS

ＡＰＰＬＩＣＡＢＩＬＩＴＹＯＦＱＵＡＳＩＣＨＥＭＩＣＡＬＭＯＤＥＬＦＯＲＳＯＭＥＬＩＱＵＩＤＡＬＬＯＹＳＷＩＴＨＳＴＲＯＮＧＩＮＴＥＲＡＣＴＥＤＣＯＭＰＯＮＥＮＴＳ①ＬｉＪｉａｎｆｅｎｇ，ＤｅｎｇＨｏｎｇｍｅｉ，ＣｈｅｎＮｉａｎｙｉＳｈａｎｇｈａｉ...     

Ultralow-concentration Sm codoping in CsI:Tl scintillator: A case of little things can make a big difference

CsI:Tl scintillators were hindered from computer tomography and high-speed imaging applications by a serious afterglow problem. In this study, the effects of ultralow-concentration Sm codoping on the scintillation characteristics of CsI:Tl were investigated. Pulsed X-ray excited afterglow after 50 ms in 0.005 mol% Sm-codoped CsI:Tl was lowered by over one order of magnitude in comparison with Sm-free one. The beneficial effects of ultralow-concentration Sm codoping also appeared to be maintaining the light yield and energy resolution. The light yield and energy resolution after 0.005 mol% Sm codoping were 71,700 ± 6000 photons/MeV and 6.9% at 662 keV, respectively.     

Effect of annealing temperature on the structural-microstructural and electrical characteristics of thallium bearing HTSC films prepared by chemical spray pyrolysis technique

In order to get good quality reproducible films of Tl : HTSC system, we have studied the different annealing conditions to finally achieve the optimized annealing condition. In the present investigation, Tl-Ca-Ba-Cu-O superconducting films have been prepared on YSZ (100) and MgO (100) single crystal substrates via precursor route followed by thallination. The post deposition heat treatments of the precursor films were carried out for various annealing temperatures (870°C, 890°C) and durations (1 and 2 min). The optimized thallination procedure occurred at 870°C for 2 min into good quality films withT _c (R = 0) ∼ 103 K for YSZ andT _c (R = 0) ∼ 98 K for MgO substrates, respectively. Further we have correlated the structural/microstructural characteristics of the films.     

CSR外靶实验终端中CsI（Tl）晶体的测试

为测量重离子加速器冷却储存环（HIRFL-CSR）的外靶实验终端上不同能量的γ射线,一种用于探测γ射线的高能量分辨的探测装置正在中国科学院近代物理研究所建设,该探测器由中国科学院近代物理研究所自行生长的铊激活的碘化铯CsI（Tl）晶体组成。与日本Hamamatsu公司生产的S8664-1010型雪崩光二极管（APD）耦合,测试其光输出的非均匀性和能量分辨,从测试结果给出了所需CsI（Tl）晶体合格的标准。目前已完成该γ探测球计划的六分之一,所提供的晶体合格率达94%以上。     

TBCCO/LAO高温超导薄膜的电阻转变和各向异性

将Tl₂Ba₂CaCu₂O₈(TBCCO)高温超导薄膜通过磁控溅射的方法沉积到LaAlO₃(LAO)衬底上,SEM和XRD的测量结果显示该超导薄膜具有很高的成膜品质.通过标准四引线方法对TBCCO/LAO高温超导薄膜在不同磁场下的电阻转变进行了研究.结果表明:在一定的磁场下TBCCO/LAO超导薄膜具有很强的电阻转变展宽现象,并且当磁场垂直于超导薄膜表面时该超导薄膜显示出更强的电阻转变展宽现象.用热激活辅助磁通流动理论对该超导薄膜的电阻转变展宽现象进行了解释,同时通过分析超导薄膜的电阻转变对该超导薄膜的各向异性进行了讨论.     

Effect of ag on processing and properties of Bi-and Tl-Based HTSC Materials

High temperature x-ray diffraction was used to determine the effect of Ag on the peritectic melting sequence of low carbon content Bi₂Sr₂CaCu₂O₈. Only slight changes in the solid solution compositions were found with 20 wt.% Ag added to the system, with the phases and stability regions remaining the same. Micro-structure, sintering behavior, lattice parameters, and superconducting property changes in Tl_0.5Pb_0.5Sr₂CaCu₂O₇ were investigated with different amounts of Ag added to investigate the effect of Ag. From the results in both systems, the presence of Ag does not seem to change the intrinsic properties of these superconductors, but affects the processing variables, like reaction temperatures, which change the optimum temperatures for obtaining best properties. The temperature at which melting occurs and the amount of liquid formed depends both on the amount of Agand carbon content of the materials.     

NaI探测器γ射线谱的计算分析

用加权的最小二乘迭代法解Nal(Tl)探测器的γ射线脉冲幅度谱。给出一个具有谱光滑增益和零点校正,自动找峰功能的计算机程序。该程序适于解连续、分列或两者迭加的γ射线脉冲幅度谱。列出了一些计算结果。     

CsI(Tl)晶体发光均匀性的研究

本文对Tl分布、几何形状以及表面条件对大尺寸锥形CsI（Tl）晶体的闪烁发光均匀性的影响进行了研究,提出了改善大尺寸锥形CsI（Tl）晶体的发光均匀性的措施.