Thermoelectric properties of unoxidized graphene/Bi2Te2.7Se0.3 composites synthesized by exfoliation/re‐assembly method

Nanocomposites of n‐type thermoelectric Bi₂Te_2.7Se_0.3 (BTS) and unoxidized graphene (UG) were prepared from the exfoliated BTS and UG nanoplatelets. Polycrystalline BTS ingots were exfoliated into nanoscoll‐type crystals by chemical exfoliation, and were re‐assembled with UG nanoplatelets. The composites were chemically reduced by hydrazine hydrate and sintered by a spark‐plasma‐sintering method. The thermoelectric properties of the sintered composites were evaluated and exhibited decreased carrier concentration and increased thermal conductivity due to the embedded graphene. The peak ZT values for the UG/BTS‐US and UG/BTS‐EX composites were ～0.8 at the UG concentration of 0.05 wt%. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Metastable β-Bi2O3 Nanoparticles with Potential for Photocatalytic Water Purification Using Visible Light Irradiation

Invited for this month′s cover is the group of Prof. Michael Mehring. The cover picture shows the degradation of the model dye rhodamine B (RhB) in water using β-Bi₂O₃ nanoparticles as photocatalyst, which was prepared from pre-organized bismuth oxido clusters. For more details, see the Full Paper on p. 146 ff.The Group of Michael MehringTechnische Universität Chemnitz Fakultät für Naturwissenschaften, Institut für Chemie Professur Koordinationschemie 09111 Chemnitz (Germany) E-mail: ed.ztinmehc-ut.eimehc@gnirhem.leahcim     

Luminescence of Thin Films of Lead and Bismuth Tungstates

The luminescence spectra of thin films of PbWO₄ and Bi₂WO₆ were investigated. It is shown that these spectra are similar and that they consist of three individual bands in the blue (2.80 eV PbWO₄ and 2.93 eV Bi₂WO₆), green (2.35 eV PbWO₄ and Bi₂WO₆), and red (1.75 eV PbWO₄ and 1.90 eV Bi₂WO₆) spectral regions. The differences in the nature of the absorption centers of excitation energy are established. The distinguishing features displayed by the temperature dependences of the individual emission bands in the PbWO₄ films are explained by energy migration between emission centers via transfer of free carriers through the conduction and valence bands.     

硫酸铵-碘化钾-乙醇体系萃取分离铋

1　引言利用高聚物水溶液在无机盐存在下可以分成两相的非有机溶剂萃取分离方法已引起人们的重视[1 ,2 ] 。本文研究发现 ,在硫酸铵存在下 ,乙醇与水分相过程中 ,Ｂｉ(Ⅲ )与Ｉ- 形成的ＢｉＩ3-6 络阴离子能被乙醇相定量萃取 ,控制一定的酸度 ,可以实现Ｂｉ(Ⅲ )与Ｆｅ(Ⅲ )、Ｃｏ(Ⅱ )、Ｍｎ(Ⅱ )、Ｃｕ(Ⅱ )、Ｎｉ(Ⅱ )、Ｍｏ(Ⅵ )之间的分离。该萃取体系与传统的有机溶剂萃取分离方法相比 ,具有平衡时间短 ,相分离速度快 ,无三相乳化 ,不使用有毒害有机溶剂 ,操作简单 ,快速均相萃取 异相分离等优点 ,既能萃取离子缔合物 ,又能萃取络阴…     

Ferroelectric Films

The preparation and properties of ferroelectric films are reviewed. Specific attention is directed to ferroelectric films prepared by wet chemical methods. Emphasis is placed on the microstructure and properties of SBT films for memory applications, and their dependence on chemistry and processing, as well as on the effects of chemistry and processing on the properties of piezoelectric and pyroelectric films. Emphasis is placed on recent results obtained in our laboratories, including modeling of the ferroelectric behavior of films and experimental results in each of these areas. Also considered is the use of ferroelectric films in memory, piezoelectric and pyroelectric devices of various types, with specific note made of the recently-announced use of pyroelectric sensors in automobiles.     

流动注射-氢化物发生-原子吸收光谱法测定胃必治中铋

采用流动注射(FI)、氢化物发生(HG)、原子吸收光谱(AAS)联用的方法,考察了各试验参数对测定抗酸药胃必治中铋的影响。方法具有分析速度快、样品用量少、灵敏度高、选择性强等特点。用于实际样品的分析,结果满意。     

Synthesis,Structural Characterization,and Cation Transport of Tripotassium Pentabismuth Arsenate K3Bi5(AsO4)6

During the exploration of the K₂O-Bi₂O ₃ -As₂O₅ system, single crystals of a new arsenate of trivalent bismuth, K₃Bi₅(AsO₄) ₆, were isolated by solid state reaction at 600°C. The title compound crystallizes in the monoclinic system, space group C2/c (N°15) with a = 18.257(2) Å, b = 7.260(1) Å, c = 20.130(4) Å, β = 119.86(1)°, and Z = 4. Its structure consists of a three-dimensional framework made up of AsO₄ tetrahedra and BiO₆ and BiO₇ polyhedra sharing edges and corners, delimiting cavities wherein K⁺ ions reside. This compound exhibits a potassium ion conductivity but with rather low conductivity value.     

层状、花形和棒状钛酸铋纳米结构的可控合成及光催化性能

通过可控水热法,制备出层状、花形和棒状钛酸铋(Bi₄Ti₃O₁₂,BIT)纳米结构。通过X射线衍射(XRD)和场发射扫描电子显微镜(FESEM)观测其结构和形貌特征。XRD图显示,所制备的样品为层状钙钛矿结构。FESEM结果表明,通过控制水热过程的反应参数可以得到不同形貌的纳米粉体。紫外-可见漫反射光谱(UV-VisDRS)表明BIT样品的带隙能约为2.63~2.95eV。利用可见光(λ>420nm)照射下的甲基橙降解实验评价了BIT样品的光催化性能。结果表明,BIT的光催化活性比掺氮TiO₂(N-TiO₂)高得多。所制备的层状BIT纳米结构光催化效率最高,经可见光照射360min,甲基橙溶液的降解率可达95.0%。同时还研究了结构和形貌对不同条件下制备的BIT样品光催化活性的影响。     

Bismuth(III) Chloride–Catalyzed Three‐Component Coupling: Synthesis of α‐Amino Phosphonates

A simple and efficient method has been developed for the one‐pot synthesis of α‐amino phosphonates from the reaction of a carbonyl compound, amine, and dialkyl phosphite. The highly catalytic nature of bismuth(III) chloride and the fact that it is relatively nontoxic, low cost, easy to handle, and insensitive to small amounts of air and moisture make this method especially attractive for large‐scale synthesis.     

球磨法制备复合光催化剂Bi12TiO20/ZnO及其光催化性能

本文用水作为分散介质,采用球磨法掺杂一定量的Bi₁₂TiO₂₀于ZnO中制备复合光催化剂Bi₁₂TiO₂₀/ZnO. 利用UV-Vis、XRD和SEM等仪器对样品进行了分析与表征. 通过对甲基橙的氧化来研究其光催化活性. 结果表明,光催化剂Bi₁₂TiO₂₀/ZnO对甲基橙氧化的催化活性高于氧化锌的催化活性.当Bi₁₂TiO₂₀的掺杂量为0.5%(质量分数),球磨时间为12 h,焙烧温度为300℃时,光照20 min后,复合光催化剂Bi₁₂TiO₂₀/ZnO对甲基橙的降解率可达到95.2%.