Rapid,nondestructive evaluation of macroscopic defects in crystalline materials: The laue topography of (Hg,Cd) Te

Several (Hg, Cd) Te semiconductor alloys have properties which make them useful as solid state detectors. However, homogeneous alloy single crystal preparation requires unusual treatment. A two-step process is necessary because of the liquidus-solidus composition disparity at the melting point. Laue topography was found to be an efficient tool for optimizing parameters in an initial quench (to preserve homogeneity) and a subsequent solid state recrystallization (to promote large grain growth). Crystal perfection analysis using polychromatic X-ray diffraction is not an entirely new concept, but our initial interest led to a simplified Laue topography technique which is useful for rapid characterization of various macroscopic crystal defects. The utility of this method is demonstrated by a study of defects in bulk (Hg, Cd)Te crystals.     

电感耦合等离子体原子发射光谱法测定金矿石中铅锌砷铋镉汞

国家标准方法测定金矿石中的铅、锌、砷、铋、镉和汞需多次溶样,操作繁琐。研究建立了混合酸消解,电感耦合等离子体原子发射光谱法同时测定金矿石中铅、锌、砷、铋、镉和汞的分析方法。实验对混合酸加入量、氟化氢铵溶液加入量、消解温度、消解时间等影响因素进行了优化。该方法各元素加入标准物质回收率为98.0%~104.0%,测定结果的相对标准偏差(n=11)为0.60%~4.76%,且与国家标准方法测定结果一致,具有操作简单,一步消解、多元素同时测定,检测效率高等优点,适用于大批量金矿石样品的检测。     

Mg2 掺杂Zn0.5Cd0.5S固溶体光催化剂的制备及光解水制氢

采用水热法制备了Cd0.5Zn0.5S和掺杂0.4%(摩尔百分数)Mg2+的0.4%Mg/Cd0.5Zn0.5S固溶体光催化剂。采用UV-Vis、XRD以及电化学等手段对催化剂进行表征,并考查催化剂可见光下分解水制氢的活性。结果表明:Mg2+掺杂提高了Cd0.5Zn0.5S固溶体中光生电子和空穴的分离效率,大大提高了Cd0.5Zn0.5S固溶体光催化制氢的活性。     

Thermodynamics of cadmium- and zinc-rich alloys in the Cd−La,Cd−Ce,Cd−Pr,Zn−La,Zn−Ce and Zn−Pr systems

The thermodynamics of the cadmium- and zinc-rich alloys in the Cd?La, Cd?Ce, Cd?Pr, Zn?La, Zn?Ce, and Zn?Pr systems have been studied with a high-temperature galvanic cell method. The values of the standard free energy of formation (kcal per mole) of the intermetallic compounds are given by the equations: $$\begin{gathered} (LaCd_{11} ), \Delta Gf^ \circ = - 72.3 + 43.6 \times 10^{ - 3} T (670^ \circ to 804^ \circ K) \hfill \\ (CeCd_{11} ), \Delta Gf^ \circ = - 70.5 + 44.6 \times 10^{ - 3} T (638^ \circ to 884^ \circ K) \hfill \\ (PrCd_{11} ), \Delta Gf^ \circ = - 69.1 + 44.8 \times 10^{ - 3} T (635^ \circ to 825^ \circ K) \hfill \\ (LaZn_{11} ), \Delta Gf^ \circ = - 92.6 + 48.0 \times 10^{ - 3} T (705^ \circ to 793^ \circ K) \hfill \\ (CeZn_{11} ), \Delta Gf^ \circ = - 87.9 + 45.0 \times 10^{ - 3} T (710^ \circ to 1018^ \circ K) \hfill \\ (PrZn_{11} ), \Delta Gf^ \circ = - 85.3 + 42.7 \times 10^{ - 3} T (696^ \circ to 875^ \circ K) \hfill \\ \end{gathered} $$ Equations are also given for the partial molar excess free energies of the lanthanide in dilute solutions of the lanthanide in liquid cadmium or zinc. The enthalpy of formation of the intermetallic compounds is discussed in terms of the crystalline structure of these intermetallic compounds. It is shown that the enthalpy of formation is a linear function of the ration/V _c , wheren is the number of zinc or cadmium atoms which are near-neighbors of the lanthanide atom andV _c is the volume of the cage formed by the near-neighbor cadmium or zinc atoms. A linear dependence of the enthalpy of formation onn/V _c is also found for the intermetallic compounds in several other binary systems. These empirical correlations are discussed in terms of a model which involves localized bonds between the lanthanide and zinc or cadmium atoms.     

Ni2+掺杂Cd0.5Zn0.5S固溶体制备及可见光分解水制氢研究

采用水热法制备了Cd0.5Zn0.5S和Ni2+掺杂Ni(m)/Cd0.5Zn0.5S固溶体光催化剂。通过XRD、UV-Vis漫反射光谱和电化学方法表征了催化剂的结构和光电性能，并考查了固溶体在以三乙醇胺为电子给体、可见光（λ≥420 nm）照射下光催化分解水制氢活性。结果表明，Ni2+掺杂后提高了催化剂对可见光的吸收，促进了光生电子—空穴的有效分离，有效提高了Cd0.5Zn0.5S固溶体的光催化制氢活性。当Ni2+的掺杂量为5%（摩尔百分数），反应体系NaOH浓度为0.5 mol/L时，催化剂活性最高，Ni(5)/Cd0.5Zn0.5S制氢活性为纯Cd0.5Zn0.5S固溶体的5倍。催化剂经15 h反应具有良好的稳定性。