机械合金化Co-Zr非晶软磁合金粉末的形成及热稳定性分析

研究了Co-Zr二元相图上4个共晶点成分配方Co90Zr10、Co53Zr47、Co35Zr65和Co21Zr79在球磨条件下的非晶态合金形成能力。采用X射线衍射和差热分析(DTA)对粉末的结构及热稳定性进行了分析。XRD分析结果表明,4种配方在一定的球磨时间内都能形成非晶态合金,其中非晶形成能力最强的为Co35Zr65。DTA分析结果表明,该合金系具有较高的热稳定性,并具有较高的非晶形成能力。球磨时间对非晶的形成有重要影响,球磨时间过长,使形成的非晶态合金粉体反而向晶体转化。     

块体Fe-Co-Zr-W-B软磁玻璃合金

块体Fe61Co10Zr5W4B20非晶软磁合金的饱和极化强度Js可达0.8 T,矫顽力JHc为2 A/m,且具有良好的玻璃形成能力,可以制成直径1 mm的棒材和外径达4 mm的薄壁管.波兰学者研究了W元素含量对Fe61Co10+xZr5W4-xB20玻璃形成能力、饱和极化强度,以及热稳定性参数的影响.     

机械合金化法制备Co-Zr非晶软磁合金粉末的研究

研究了Co-Zr二元相图上4个共晶点成分配方Co90Zr10、Co53Zr47、Co35Zr65和Co21Zr79在球磨条件下的非晶态合金形成能力。分析结果表明,4种配方在一定的球磨时间内都能形成非晶态合金,其中非晶形成能力最强的为Co35Zr65。球磨时间对非晶的形成有重要影响,球磨时间过长,使形成的非晶态合金粉体反而向晶体转化。     

Fe(Co,Ni)ZrB非晶/纳米晶的制备及晶化过程研究

采用机械合金化法制备了Fe70Zr10B20、Fe63Co7Zr10B20和Fe63Ni7Zr10B20合金.利用X射线衍射仪(XRD)研究了3种合金的机械合金化过程及晶化过程.Fe70Zr10 B20球磨50h后的合金由大量非晶相和少量晶态相组成,Co的添加对FeZrB非晶合金的形成起到了抑制作用;Ni的添加对FeZrB非晶合金的形成起到了促进作用.Fe70-Zr10B20、Fe63Co7Zr10B20合金的晶化过程容易进行,而Fe63 Ni7Zr10 B20合金的晶化比较困难.     

(Fe0.5Ni0.5)80-xMoxB20非晶态合金的玻璃形成能力与热稳定性

采用XRD,TEM,DSC研究了(Fe0.5Ni0.5)80-xMoxB20 (x＝0, 2, 4, 6, 8)非晶态合金的玻璃形成能力和热稳定性,讨论了非晶态合金玻璃形成能力的表征,探讨了Mo对玻璃形成能力和热稳定性的作用机理.结果表明: Mo的加入可提高(Fe0.5Ni0.5)80B20合金的玻璃形成能力和热稳定性;Tx/Tm可用于表征(Fe0.5Ni0.5)80-xMoxB20非晶态合金的玻璃形成能力;合金组元数目增多、原子尺寸比增大及负混合热是Mo提高玻璃形成能力的主要原因.     

Ti-Zr-Be-Cu块体非晶合金添加不同含量Co后在HCl溶液中的腐蚀行为

添加合金元素可提高非晶合金的耐蚀性.对Ti-Zr-Be-Cu块体非晶合金添加Co,采用电化学极化曲线和浸泡腐蚀法研究所制备的Ti35Zr30Be27.5-xCu7.5Cox(x=3.5,7.5,11.5)块体非晶合金在不同温度1 mol/L HCl溶液中的腐蚀行为,探讨添加Co元素提高Ti-Zr-Be-Cu块体非晶合金耐蚀性的机理.结果表明:Ti35Zr30Be27.5-xCu7.5Cox块体非晶合金在298 K的1 mol/L HCl溶液中都具有很好的耐蚀性,阳极极化曲线表现出明显的钝化特征,随着Co元素含量的增大其耐蚀性能逐渐增强,非晶合金的自腐蚀电位高于不锈钢,自腐蚀电流密度比不锈钢小1个数量级;在313,333 K的1 mol/L HCl中浸泡腐蚀失重,随Co含量增大,非晶合金耐蚀性增强.     

Fe61Co10Zr5W4B20块体非晶合金的形成及其力学性能

采用铜模吸铸法获得直径为2 mm的Fe61Co10Zr5W4B20块体非晶合金.采用X射线衍射、扫描电镜、示差扫描量热仪、微显硬度及压缩实验等研究了非晶合金的结构、热稳定性、显微硬度与压缩性能.结果表明:Mo的引入不利于非晶合金的形成;Fe61Co10Zr5W4B20块体非晶合金表现为二级晶化,玻璃转变温度为561.1℃,晶化起始温度为619.0℃,第一晶化峰值温度为632.6℃,第二晶化峰值温度为747.0℃,过冷液相区为57.9℃;该非晶合金的显微硬度为1207HV0.2,抗压强度σbc为1707.6 MPa.     

机械合金化制备Nd60 Fe20 Al10 Co10非晶粉末的研究

利用机械合金化制备Nd60Fe20Al10Co10非晶粉末，采用X射线衍射(XRD)和振动样品磁强计(VSM)研究Nd60Fe20Al10Co10非晶的形成过程、磁性能变化及其与成分结构的关系。结果表明，90min后Al原子溶入Nd原子形成固溶体。球磨2h后出现少量非晶，20h后Co单质和Nd单质消失．组织为非晶相(含少量的α-Fe)。球磨100h最终得到非晶 少量的α-Fe纳米晶。球磨过程中，矫顽力随着合金中非晶的量增加而升高．球磨20h矫顽力达到43kA／m。Nd60Fe20Al10Co10合金具有硬磁性是由于非晶相的存在而造成的。     

重稀土元素添加对Cu-Zr-Al合金非晶形成和力学性能的调控

稀土元素是改善非晶态合金形成能力和性能的重要添加剂,本文采用铜模吸铸法制备了一系列Cu50-x Zr46Al4REx(RE=Dy,Tb,Gd;x=0,1,2,3,4)非晶态合金,系统地探究了重稀土元素Dy、Tb、Gd添加对Cu-Zr-Al合金非晶形成能力(GFA)和力学性能的影响.实验结果表明加入重稀土元素Dy、Tb、...     

Fe80-xCoxZr8Ge2B10 (x=0,8, 16)合金的热性能、结构和磁性能

用单辊快淬法制备Fe80-xCoxZr8Ge2B10(x=0,8,16)非晶合金,再对3种合金进行不同温度下退火处理.利用差热分析仪(DTA)、X射线衍射仪(XRD)和振动样品磁强计(VSM)等测试手段对样品的热性能、微观结构及磁性能进行研究.结果表明,Fe80-xCox Zr8 Ge2 B10(x=0,8,16)合金在快淬态时均形成非晶.Fe80 Zr8 Ge2B10和Fe72 Co8 Zr8 Ge2 B10的晶化过程类似,比较复杂;Fe64 Co16 Zr8 Ge2 B10合金的晶化过程不同于其他两种合金,相对简单.3种合金的比饱和磁化强度整体上随着Co含量的增加而增大.     

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.     

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.     

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.     

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.     

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.     

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.     

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.