Impurity induced structural phase transformations in melt grown single crystals of lead iodide

Lead iodide is a wide‐band gap and highly resistive semiconductor considered to be a promising room temperature nuclear detector. The phenomenon of polytypism is posing interesting problems of phase transformations among its polytypic modifications and formation of polytypic admixture during growth due to native impurities. Transformations have also been observed even when the material is stored for few months that causes deterioration in functioning of the PbI₂ devices. Lead iodide has been purified and single crystals were grown using zone‐refining system. The observed phase transformations during growth and storage have been explained in the light of distortion of [PbI₆]^4‐ octahedron due to impurities present in the material and the known crystal structures of PbI₂. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

管理者过度自信对并购绩效的影响——基于群体决策视角的分析和实证

我国公司决策更多的是群体而非个体决策,群体决策强化还是弱化了过度自信偏差?本文从群体决策的层面研究了管理者的过度自信对公司并购绩效的影响。摈弃传统公司并购理论中的管理者理性假设,从行为公司金融理论出发,以我国422家上市发行A股的并购公司为样本进行了实证分析和研究。结果表明:群体决策中的管理者普遍存在着过度自信;管理者过度自信与并购长期绩效显著负相关;与短期绩效也负相关,但在统计上不显著。最后,根据分析结果提出了克服或减少管理者决策偏差行为的若干可行的举措。     

方形钢筋混凝土板的近场抗爆性能

为了探讨钢筋混凝土板在爆炸载荷作用下的抗爆性能,对方形钢筋混凝土板在单向支撑条件下进行了近场爆炸加载实验,实验中采取TNT装药对钢筋混凝土板进行加载。并利用AUTODYN 软件采用流固耦合算法,建立了混凝土和钢筋三维分离式实体模型,对钢筋混凝土板的动态响应过程进行数值模拟,且考虑应变率对钢筋和混凝土材料的动态本构特性的影响。模拟得到的钢筋混凝土板破坏现象与实验结果吻合较好。在此基础上,分析了不同质量的装药作用下钢筋混凝土板的损伤和破坏特征,合理展现了钢筋混凝土板从混凝土开裂、底部层裂碎片形成、钢筋屈服到混凝土板局部震塌的动态演变过程。研究结果表明,随着装药质量的增加,方形钢筋混凝土板的破坏模式逐渐由整体弯曲破坏转变为局部冲切破坏。     

一种高容量的层状Co-MOF基超级电容器电极材料

通过简单的溶剂热反应合成了一种钴基层状MOF（[Co（4,4''-bpy）（tfbdc）（H₂O）₂],Co-BTH,4,4''-bpy=4,4''-联吡啶,H₂tfbdc=四氟对苯二甲酸）,并考察了其作为超级电容器电极材料的性能。研究结果表明：Co-BTH电极具有良好的赝电容性能,包含高比电容和较好的倍率性能。在1 A·g^-1电流密度下和1 mol·L^-1 KOH溶液中,其比电容最大可达2 316 F·g^-1。在2 A·g^-1的电流密度下,循环1 000次后,电极的比电容仍然还有847 F·g^-1。良好的赝电容性能与Co-BTH的层状结构和小尺寸的纳米片有关。     

BTBPD-PC61BM体系光伏性质的密度泛函理论计算

Designing and fabricating high-performance photovoltaic devices have remained a major challenge in organic solar cell technologies.In this work,the photovoltaic performances of BTBPD-PC₆₁BM system were theoretically investigated by means of density functional theory calculations coupled with the Marcus charge transfer model in order to seek novel photovoltaic systems.Moreover,the hole-transfer properties of BTBPD thin-film were also studied by an amorphous cell with 100 BTBPD molecules.Results revealed that the BTBPDPC₆₁BM system possessed a middle-sized open-circuit voltage of 0.70 V,large short-circuit current density of 16.874 mA/cm²,large fill factor of 0.846,and high power conversion efficiency of 10%.With the Marcus model,the charge-dissociation rate constant was predicted to be as fast as 3.079×10¹³ s^-1 in the BTBPD-PC₆₁BM interface,which was as 3-5 orders of magnitude large as the decay (radiative and non-radiative) rate constant (10⁸-10¹⁰ s^-1),indicating very high charge-dissociation efficiency (～100%) in the BTBPD-PC₆₁BM system.Furthermore,by the molecular dynamics simulation,the hole mobility for BTBPD thin-film was predicted to be as high as 3.970×10^-3 cm²V^-1s^-1,which can be attributed to its tight packing in solid state.     

焦粉活性炭/Al-Ni(OH)2复合电极材料的制备及其超级容器性能

以焦粉为原料,用HNO3预处理除灰,采用KOH浸渍-煅烧活化法制备焦粉活性炭(CPAC),通过场发射扫描电子显微镜、X射线衍射等表征其形貌,采用BET测试其比表面积、孔结构及孔径分布。初步考察了活化温度、活化时间等对焦粉活性炭电极材料电化学性能的影响。采用共沉淀法制备CPAC/Al-Ni(OH)2复合电极材料,通过恒电流充放电测试及循环伏安测试表征CPAC/Al-Ni(OH)2复合电极材料的电化学性能。结果表明,当活化温度为800℃、活化时间为3 h制得的焦粉活性炭电极材料的电化学性能最佳,比电容达到211 F/g。CPAC-800℃-3 h/Al-Ni(OH)2复合电极材料随Al掺杂量的增大呈现先增大后减小的趋势。在固定Al质量掺杂量为4%,炭镍质量比为1∶1时所得复合材料的比电容量最大:1173.6 F/g。恒电流充放电及循环伏安测试表明Al掺杂量为4%、炭镍比为1∶1的复合材料具有较好的电化学性能。     

环境因素对独立学院办学效益的影响——基于DEA的实证分析

为提高独立学院教育资源配置效率,基于数据包络分析理论,构建了独立学院相对办学效益测评指标体系及模型,将独立学院所在地区经济、人口和母体高校声誉等环境因素视为不可控投入要素纳入其中,分析了这些环境因素对45所独立学院办学效益的影响,得出了一个有趣的结论:即使环境因素对独立学院的办学效益不起主要作用,但是,可能会显著影响其投入与产出的改进量.