Bi2Te3热电薄膜的电化学原子层外延制备

采用电化学原子层外延法(ECALE)在Au电极上成功地制备了Bi2Te3化合物热电薄膜.通过循环伏安扫描研究Te和Bi在Au衬底上的电化学特性,使用自动沉积系统交替欠电位沉积Te、Bi原子层200个循环获得沉积物.XRD、EDX和FESEM测试结果表明循环沉积200层后得到的沉积物Bi和Te的化学计量比为2:3,且是Bi2Te3薄膜化合物,而非单质Bi和Te的简单混合;薄膜均匀、致密、平整且可重复性好,以(015)为最优取向外延生长的.     

电化学原子层外延制备Bi—Se系薄膜

采用电化学原子层外延（electrochemical atomic layer epitaxy，ECALE）方法尝试在Pt电极上沉积Bi2Se3纳米热电薄膜。利用循环伏安扫描研究了Bi^3＋、Se^4＋在Pt电极上的欠电势沉积参数，在此基础上利用自动电沉积系统交替沉积400个Bi、Se原子层。采用电量分析、XRD、EDX对沉积物进行表征。电量分析表明沉积物中存在硒的富余，XRD结果表明沉积物中除了Bi2Se3化合物外还有单质Se的富余。EDX分析沉积物的硒铋原子比为4：1，与XRD分析结果一致。     

电化学原子层外延及其新材料制备应用研究进展

电化学原子层外延(ECALE)是电化学沉积和原子层外延技术的结合,通过运用欠电势技术交替电化学沉积化合物的组成元素一次一个原子层而实现外延生长.详细介绍了电化学原子层外延(ECALE)的基本原理和特点,分析了影响ECALE过程的关键要素,并进一步介绍了它在新材料制备中的应用研究进展.     

纳米热电材料及其ECALE制备方法进展

论述了纳米热电材料的发展现状及其提高热电优值（ZT）的机理,介绍了一种制备纳米热电薄膜的新方法--电化学原子层外延（ECALE）,它采用欠电位沉积实现二维层状生长.文中还总结了该方法制备纳米薄膜过程中的几个重要影响因素,并预测了纳米热电材料和器件今后的研究方向.     

Ⅱ-Ⅵ族化合物半导体电化学原子层外延

介绍一种外延沉积化合物半导体材料的新方法──电化学原子层外延技术，它将电化学沉积技术与原子层外延技术结合起来，通过运用欠电势技术交替电化学沉积化合物的组成元素一次一个单原子层而实现外延生长。从而使外延技术具有电沉积简单与低成本的优点。欠电势沉积是电化学原子层外延的关键，它是化合物形成过程中放出自由能的结果。并研究了Si-Au多晶衬底上沉积CdTe的电化学原子层外延，给出了初步实验结果。     

射频磁控溅射制备Bi2Te3热电薄膜

通过射频磁控溅射，在溅射气体为Ar，气压为1Pa，溅射功率为120W时分别在聚氨酯和玻璃基底上沉积了不同厚度的Bi2Te3薄膜。Bi2Te3薄膜主要是以（221）晶面平行于基底进行外延生长，先在基底形成大量微小晶粒，合并长大成典型的纤维状组织结构。在此条件下薄膜生长速率为26nm/min，通过控制溅射时间可沉积几纳米到几微米不同厚度的薄膜。得到的p-型半导体Bi2Te3薄膜，其电阻率随薄膜厚度的增大而减小。     

Ⅱ—Ⅵ族化合物半导体电化学原子层外延

介绍了一种外延沉积化合物半导体材料的新方法－电化学原子层外延技术，它将电化学沉积技术与原子层外延技术结合起来，通过运用欠电热技术交替电化学沉积化合物的组成元素一次一个单原子层而实现外延生长。从而使外延技术具有电沉积简单与低成本的优点。     

Bi-Te-Se热电薄膜的电化学沉积

在含有Bi 3＋、HTeO2＋、Se4＋离子的水溶液中通过电化学方法实现了Bi2Te3-ySey热电薄膜沉积,研究了电沉积Bi2Te3-ySey的阴极极化曲线及热电薄膜的生长过程,通过电子显微镜（SEM）和能谱仪（EDS）等手段对热电薄膜进行了形貌、成分分析。结果表明电解液的离子组成、沉积电位对薄膜成分、形貌有较大影响。在-0.07V沉积电位下制备的热电薄膜Bi2Te2.75Se0.95晶粒大小均匀,结构致密。     

Bi2-xSbxTe3温差电材料薄膜的电化学制备、表征及性能研究

采用电化学控电位沉积的方法制备了Bi2-xSbxTe3温差电材料薄膜.通过ESEM、XPS、XRD、EDS等方法对电沉积薄膜的形貌、结构和组成进行了研究,并测试了在不同电位下制备的Bi2-xSbxTe3薄膜的温差电性能.研究结果表明,在含有Bi3+、HTeO+2和SbO+的溶液中,采用控电位沉积模式,可实现铋、锑、碲三元共沉积,生成锑掺杂的Bi2Te3化合物Bi2-xSbxTe3.通过调节沉积电位,可控制电沉积Bi2-xSbxTe3薄膜的掺杂浓度,从而影响材料的温差电性能.控制沉积电位为-0.5V条件下制备的温差电材料薄膜的塞贝克系数最大,为213μV·K-1,其组成为Bio.5Sb1.5Te3.随着沉积电位的负移,电沉积出的Bi2-xSbxTe3薄膜的结晶状态将逐渐由等轴晶转变为树枝晶.研究证明,电沉积方法可以制备出性能优异的薄膜温差电材料.     

Pt／n—n＋-Si电极上化学沉积铁氰化镍薄膜及其应用

在表面外延生长9μm的n型层的磷重掺杂的硅基底n—n＋一Si）结构上沉积约40nm铂（Pt）,经氩气保护673K热处理30min作为半导体电极（Pt／n—n＋-Si）。将半导体电极和铁氰化钾、硫酸镍以及硝酸钠的溶液接触,沉积出稳定的铁氰化镍（NiHCF）薄膜。复合电极与Pt电极组成光电化学电池,在零偏电压条件下,通过测量该电池的光电流可检测过氧化氢。通过循环伏安和X-光电子能谱对NiHCF薄膜进行了分析与表征。     

Magnetic coupling in La0.67Ca0.33MnO3/La0.67Sr0.33CoO3/La0.67Ca0.33MnO3 sandwiches

La_0.67Ca_0.33MnO₃ (LCMO)/La_0.67Sr_0.33CoO₃ (LSCO)/LCMO trilayer films are fabricated on single-crystal substrates NdGaO₃ (110) and the interlayer coupling are investigated. Compared with LCMO single layer, sandwiches showed the enhanced metal-insulator transition temperature of LCMO layers. The magnetoresistance is dependent on spacer thickness and the peak value dramatically decreases when LSCO layer is thick enough because of shorting by the LSCO layer. The magnetic coercivity H_C shows a nonmonotonic behavior with changing spacer layer thickness and the waist-like hysteresis indicates that there is an indirect exchange coupling between the top and bottom LCMO layers across the spacer layer.     

Varistor properties of ZnO-Pr6O11-CoO-Cr2O3-Y2O3-In2O3 ceramics

The varistor properties of the ZnO-Pr₆O₁₁-CoO-Cr₂O₃-Y₂O₃-In₂O₃ ceramics were investigated for different concentrations of In₂O₃. The increase of In₂O₃ concentration slightly increased the sintered density (5.60-5.63 g/cm³) and slightly decreased the average grain size (3.4-2.9 μm). The breakdown field increased from 6023 to 14822 V/cm with increasing concentration of In₂O₃. The nonlinear coefficient increased from 17.6 to 44.6 for up to 0.005 mol%, whereas the further doping caused it to decrease to 36.8. In₂O₃ acted as an acceptor due to the donor concentration, which decreases in the range of 1.02 × 10¹⁷ to 0.24 × 10¹⁷/cm³ with increasing concentration of In₂O₃.     

Nanocrystallization of SrBi2Nb2O9 from glasses in the system Li2B4O7---SrO---Bi2O3---Nb2O5

Transparent glasses in the system (100−x)Li₂B₄O₇–x(SrO---Bi₂O₃---Nb₂O₅) (10≤x≤60) (in molar ratio) were fabricated by a conventional melt-quenching technique. Amorphous and glassy characteristics of the as-quenched samples were established via X-ray powder diffraction (XRD) and differential thermal analyses (DTA) respectively. Glass–ceramics embedded with strontium bismuth niobate, SrBi₂Nb₂O₉ (SBN) nanocrystals were produced by heat-treating the as-quenched glasses at temperatures higher than 500 °C. Perovskite SBN phase formation through an intermediate fluorite phase in the glass matrix was confirmed by XRD and transmission electron microscopy (TEM). Infrared and Raman spectroscopic studies corroborate the observation of fluorite phase formation. The dielectric constant (_r) and the loss factor (D) for the lithium borate, Li₂B₄O₇ (LBO) glass comprising randomly oriented SBN nanocrystals were determined and compared with those predicted based on the various dielectric mixture rule formalism. The dielectric constant was found to increase with increasing SBN content in LBO glass matrix.     

PbSbBiS4-Sb2S3 and PbSbBiS4-Bi2S3 joins in the PbS-Sb2S3-Bi2S3 system

Phase equilibria along the PbSbBiS₄-Sb₂S₃ and PbSbBiS₄-Bi₂S₃ joins of the PbS-Sb₂S₃-Bi₂S₃ system have been studied for the first time using differential thermal analysis, X-ray diffraction, microstructural analysis, microhardness tests, and density measurements, and the phase diagrams of the joins have been mapped out. The joins are shown to be pseudobinary with limited series of terminal solid solutions. The solid solutions are p-type semiconductors.     

Syntheses of hollandite type Rb2Cr8O16, K2Cr2V6O16 and K2V8O16

Hollandite-type compounds, Rb₂Cr₈O₁₆, K₂Cr₂V₆O₁₆ and K₂V₈O₁₆, were synthesized under high P-T conditions up to 1200°C and 7GPa. The structural refinement using a single crystal of Rb₂Cr₈O₁₆ confirms that the structure is similar to that of K₂Cr₈O₁₆. Magnetic measurements indicate that Rb₂Cr₈O₁₆ is ferromagnetic below 295K, K₂Cr₂V₆O₁₆ paramagnetic down to 77K and K₂V₈O₁₆ has susceptibility anomaly at 175K. These compounds are all semiconductive and show discontinuities in temperature-resistivity curves at points corresponding to magnetic anomalies.     

Microstructures of YBa2Cu3O7/La0.7Ca0.3MnO3 and La0.7Ca0.3MnO3/YBa2Cu3O7 bi-layers grown on (001)LaAlO3

Epitaxial YBa₂Cu₃O₇/La_0.7Ca_0.3MnO₃ (YBCO/LCMO) bi-layers and La_0.7Ca_0.3MnO₃/YBa₂Cu₃O₇ (LCMO/YBCO) bi-layers were grown on (001)LaAlO₃ by pulsed laser deposition, and their microstructures were compared by transmission electron microscopy investigation. In the YBCO(100 nm)/LCMO(150 nm) bi-layers, the LCMO layer consists of columnar grains of ~ 17 nm in diameter and contains mixed orientation domains of [100]_c, [010]_c and [001]_c. The YBCO layer is totally c-axis oriented and the YBCO lattices are tilted − 2.5° to + 2.5° as they grew on the rough surfaces of LCMO columnar grains. For the LCMO(140 nm)/YBCO(140 nm) bi-layers, the LCMO/YBCO interface is sharp and flat. The initial 12-nm thickness of the YBCO layer is composed of c-axis oriented domains, and the upper part of YBCO layer is [100] oriented. The LCMO layer was predominantly [001]_c oriented while [100]_c-oriented domains were occasionally observed.     

Characterization of YBa2Cu3O7/PrBa2Cu3O7 superlattices

We investigated the structural and superconducting properties ofc-axis oriented (YBa₂Cu₃O₇) _nY /(PrBa₂Cu₃O₇) _npr superlattices with thicknesses of the individual layers down to one unit cell (10nY1; 18>nPr 1). By transmission electron microscopy and X-ray diffraction we find an excellent structural quality of the samples, though the quantitative analysis shows the existence of defects. In superlattices with decoupled YBa₂Cu₃O₇ layers of two unit cell thickness we find a highT _c value of 75 K. We probed the flux line structure in the superlattices by measurements of the critical current density in magnetic fields. The experiments show that the flux-line dynamics is dominated by the movement of pancake vortices.     

Structural study of Sr0.3Ba0.7Nb2O6 and La0.030Sr0.255Ba0.700Nb2O6 ceramic systems

Sr_0.3Ba_0.7Nb₂O₆ (SBN) and La_0.030Sr_0.255Ba_0.700Nb₂O₆ (LSBN) ceramic compounds have been prepared using the traditional ceramic method at two different calcination temperatures (900 and 1000 °C) and later sintered both at 1400 °C. A study of the effects of the calcination temperatures and La substitution on the morphological, compositional, and structural properties of SBN and LSBN is presented using scanning electronic microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) analysis. From Rietveld refinement processes, the XRD patterns were interpreted to evaluate such effects in the structural parameters and the site occupation factors of the heavy metals and oxygen atoms. The effect of the incorporation of La resulted in a 0.25% cell contraction and turned out to be higher than the 0.08% dilation effect produced by the increase of calcination temperature. The La ion with similar effective ionic radius and higher electronegativity is incorporated into the structure occupying the A₁ site just like the Sr ions in the SBN compound. Differences in the site occupation factors between the SBN and LSBN samples lead to substantial changes in the physical properties such as temperature of relative dielectric constant maximum, relative dielectric constant, and dielectric loss, correlated with the distortion and the relative orientation of the oxygen octahedra.     

Vapour-liquid equilibria in the ternary mixtures N2---CH4---C2H6 and N2---C2H6---C3H8

A systematic study was performed with mixtures consisting of N₂, CH₄, C₂H₆ and C₃H₈, to investigate experimentally phase equilibria and caloric properties and to test the accuracy of thermodynamic correlations. The first part of this Paper reports results of T---p---x---y measurements on ternary systems in the range 20 < p < 120 bar and 140 < T < 220 K. The results are compared with data calculated by generalized equations of state.     

The effect of Bi1.5Zn0.5Nb0.5Ti1.5O7 cover layer on the dielectric and tunable properties of Ba0.6Sr0.4TiO3/Bi1.5Zn0.5Nb0.5Ti1.5O7 bilayered thin films

Bi_1.5Zn_0.5Nb_0.5Ti_1.5O₇ (BZNT) thin films with different thicknesses as cover layers were deposited on the Ba_0.6Sr_0.4TiO₃ (BST) thin films on the Pt/Ti/SiO₂/Si substrates by radio frequency magnetron sputtering method. The microstructure, surface morphology, dielectric and tunable properties of BST/BZNT heterogeneous bilayered films were investigated as a function of the thickness of BZNT films and the effect of BZNT films on the asymmetric electrical properties of BST/BZNT bilayered films was discussed. It was found that BZNT cover layer significantly improved the leakage current and the dielectric loss, and the dielectric constant and tunability of BST/BZNT bilayered thin films simultaneously decreased with the increasing thickness of BZNT films. The BST/BZNT bilayered thin film with a 50 nm BZNT cover layer gave the largest figure of merit (FOM) of 33.48 with the upper tunability of 55.38%. The asymmetric electrical behavior of BST/BZNT bilayered films is probably related to an internal electric field caused by built-in voltages at Pt/BST and BZNT/Au interfaces.