Crystal Radii and Their Application on the Study of Electronic Structures of LaX(X=N,P,As,Sb)

以Ｐｈｉｌｉｐｓ－ＶａｎＶｅｃｈｔｅｎ理论和晶体光学性质为基础，计算了ＬａＸ（Ｘ＝Ｎ，Ｐ，Ａｓ，Ｓｂ）晶体的离子半径（单位：ｎｍ）：（Ｌａ：Ｎ）为（０．１４１４，０．１２３６），（Ｌａ：Ｐ）为（０．１５１８，０．１４８９），（Ｌａ：Ａｓ）为（０．１５３６，０．１５２６），（Ｌａ：Ｓｂ）为（０．１５８６，０．１６５１）．用ＬＭＴＯ－ＡＳＡ方法对ＬａＸ系列晶体的能带结构进行了计算．所得到的能隙是：ＬａＮ为２．３０ｅＶ，ＬａＰ为２．０５ｅＶ，ＬａＡｓ为１．６６ｅＶ，ＬａＳｂ为１．３４ｅＶ．与实验结果相符．这也证明了作者得到的半径的合理性．     

Screen Printed Carbon Electrode Modified with Poly(L‐Lactide) Stabilized Gold Nanoparticles for Sensitive As(III) Detection

Poly(L ‐lactide) stabilized gold nanoparticles (designated as PLA–Au^NP) with an average particle size of ca. 10 nm were used to modify a disposable screen‐printed carbon electrode (SPE) for the detection of As(III) by differential pulse anodic stripping voltammetry. Gold modification was evaluated by cyclic voltammetry, whereas scanning electron microscopy and transmission electron microscopy revealed the size and distribution of gold nanoparticles. The PLA–Au^NP/SPE was applied effectively to detect toxic As(III) in HCl medium. Under the optimal experimental conditions, a linear calibration curve up to 4 ppm with a detection limit (S/N=3) of 0.09 ppb was obtained. The sensitivity was good enough to detect As(III) at levels lower than the current EPA standard (10 ppb). Most importantly, the PLA–Au^NP/SPE can be tolerable from the interference of Cu, Cd, Fe, Zn, Mn, and Ni and hence provides a direct and selective detection method for As(III) in natural waters. Practical utility of the PLA–Au^NP/SPE was demonstrated to detect As(III) in “Blackfoot” disease endemic village groundwater from southwestern coast area of Taiwan (Pei‐Men).     

Ge2Sb2Te5的化学机械抛光研究进展

相变存储器由于具有非易失性、高速度、低功耗等优点被认为最有可能成为下一代存储器的主流产品,Ge2Sb2Te5(GST)作为一种传统相变材料已经被广泛应用在相变存储器中,而GST的化学机械抛光作为相变存储器生产的关键工艺目前已被采用.本工作综述了有关GST的化学机械抛光技术研究进展,讨论了GST化学机械抛光过程的影响因素,如下压力、转速、抛光垫、磨料、氧化剂、表面活性剂等,并对目前GST的化学机械抛光机理进行了归纳,进一步展望了GST的化学机械抛光技术的发展前景.     

Solar Light Photocatalytic Degradation of Malachite Green by Hydrothermally Synthesized Strontium Arsenate Nanomaterial through Response Surface Methodology

Nanostructured Sr₂As₂O₇ samples were synthesized by hydrothermal crystal growth reactions between Sr(NO₃)₂ and As₂O₃ with different stoichiometric Sr:As molar ratios as 1:1 (S₁), 1:2 (S₂), and 2:1 (S₃). The synthesized nanomaterials were characterized by powder X‐ray diffraction (PXRD) technique and fourier‐transform infrared (FT‐IR) spectroscopy. Rietveld analysis showed that the obtained materials were crystallized well in the monoclinic crystal structure with the space group P2₁. The morphologies of the synthesized materials were studied by field emission scanning electron microscopy (FESEM) technique. TEM images verified formation of the particles with nanometer size. Ultraviolet‐visible spectra analysis showed that the synthesized Sr₂As₂O₇ nanomaterials had strong light absorption in the ultraviolet light region. Photocatalytic performance of the synthesized nanomaterials was also investigated for the degradation of pollutant Malachite Green (4‐{[4‐(dimethylamino)phenyl](phenyl)methylidene}‐N′N‐dimethylcyclohexa‐25‐dien‐1‐iminium chloride) (MG) in aqueous solution under solar light condition. The optimal conditions were obtained by design expert software for S₁. It was found that the optimum condition was 0.14 mL H₂O₂, 20 mg catalyst, and 33 min time. The volume and concentration of the as prepared MG solution were 70 mL and 100 ppm, respectively, for obtaining the optimum conditions. The degradation yield in the optimized conditions was 97 % for S₁.     

Ba1-xKxFe2As2单晶(Tc=38.5K)磁通钉扎力与钉扎机理研究

铁基超导体是在2008年由Hosono发现的一种新型超导材料, 由于其具有上临界场高、各向异性小、临界电流密度大等优点, 在世界范围内引起了广泛关注. 以Ba_1-xK_xFe₂As₂为代表的FeAs-122系超导体具有结构简单、合成温度低、单晶容易制备等优点, 是物理学家和材料学家关注的焦点. 本工作在获得最优化掺杂的Ba_1-xK_xFe₂As₂单晶(T_c = 38.5 K)基础上, 通过分析其在不同磁场条件下电阻温度变化关系、不同温度条件下的磁滞回线等数据, 系统的研究了Ba_1-xK_xFe₂As₂单晶磁通钉扎力和磁通钉扎机理. 研究发现Ba_1-xK_xFe₂As₂超导体具有非常高的磁通钉扎势, 其中9 T的外场条件下, 其在H//c轴和H//ab面的钉扎势分别为5800 K和8100 K, 展示出良好的应用前景; 通过进一步分析发现, 其磁通钉扎机理应是由于晶格内部的小尺寸缺陷引起的电子平均自由程变化而导致的δl钉扎.     

First principles study of isostructural phase transition in Sb2Te3 under high pressure

The structural properties, electronic band structure and Bader charge of Sb₂Te₃ under hydrostatic pressure were simulated using density functional theory in order to study isostructural phase transitions (IPT) in Sb₂Te₃. The theoretical results showed that the axial ratio c /a did not exhibit any anomaly below 6 GPa. The variations of bond lengths were discontinuous at 2.5 GPa, which suggested considerable changes in interatomic interactions and provided sound support to the IPT. The effective charges of Sb and Te atoms showed significant discontinuous variations at 2.5 GPa, which revealed a strong redistribution of the electronic charge density and considerably changed interactions among bonding atoms. Thus, the IPT is originated from the considerable variation in the electronic charge density. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)