Te掺杂方钴矿CoSb3的溶剂热合成及电学性能

以CoCl₂, SbCl₃和Te粉为原料, NaBH₄为还原剂, 用溶剂热方法合成了Te掺杂方钴矿CoSb_3-xTe_x(x=0, 0.05, 0.1, 0.2, 0.4)纳米粉末. 研究发现, Te含量较高的样品(x≥0.2)有明显的CoTe₂等杂相存在. CoSb_3-xTe_x合成粉末的粒径大小在40nm左右, 热压后晶粒发生长大, 平均晶粒尺寸约为300nm. 电学性能测试表明Te掺杂方钴矿CoSb_3-xTe_x的导电类型为n型, Seebeck系数的绝对值随着Te含量的增加而变小, 电导率随着Te含量的增加而增大. 在测试温度范围内, CoSb_2.8Te_0.2 具有最高的功率因子, 在773K温度下达到2.3×10³W·m^-1·K^-2.     

压力对CoSb_(2.750)Te_xGe_(0.250-x) n型方钴矿化合物的电输运性能的影响

采用高温高压方法,在900K的温度条件下,成功合成出CoSb2.750 TexGe0.250-x(x=0.125,0.175,0.200)n型方钴矿化合物,并考察了不同的压力对其电输运性能的影响规律。室温下对样品的电阻率(ρ),Seebeck系数(S)进行了测试分析。电学性能测试表明,方钴矿CoSb2.750 TexGe0.250-x化合物的导电类型为n型,电阻率和Seebeck系数的绝对值随着压力的升高而增加,随着Te掺杂量的增加而降低。功率因子随合成压力增大而降低,随Te掺杂量的增加而升高。CoSb2.750Te0.200Ge0.050在2GPa时具有最大的功率因子为7.59μW/(cm.K2)。     

In掺杂对CdMnTe晶体性能的影响

采用垂直Bridgman法生长了In掺杂Cd0.3Mn0.2Te晶体（CdMnTe：In）和本征的Cd0.8Mn0.2Te晶体（CdMnTe）。X射线粉末衍射、X射线双晶摇摆曲线和位错密度测试表明，所生长晶体均为立方闪锌矿结构，半峰宽为40～80arc Sec，位错密度为100～100cm^-2，结晶质量良好．In掺杂不影响晶体的结构和结晶质量。电流．电压（I-V）测试表明，CdMnTe：In晶体的电阻率为1～3×10^9Ω·cm，与CdMnTe晶体相比上升了3个数量级．近红外光透过光谱（IR transmission）研究发现In掺杂后CdMnTe晶体红外透过率降低，在波数范围4000～1000cm^-1，CdMnTe晶体红外透过率为51．2％～56．4％，而CdMnTe：In的红外透光率为15．4％～6％。     

球形LiNi0.5-xCo2xMn0.5-xO2的合成及其电化学性能

以化学共沉淀法制备的球形Ni0.5-xCo2cMn0.5-xCO3（x=0.075,0.1,1/6）为前驱体合成了球形锂离子电池正极材料LiNi0.5-xCo2xMn0.5-xO2（x=0.075,0.1,1/6）,研究了钴含量对LiNi0.5-xCo2xMn0.5-xO2的物理性能和电化学性能的影响.SEM研究表明,球形LiNi0.5-xCo2xMn0.5-xO2由许多一次颗粒构成,随着钴含量的增加,产物中一次颗粒增大.XRD分析表明,LiNi0.5-xCo2xMn0.5-xO2均为具有层状结构的纯相物质.电化学性能测试结果显示,LiNi0.5-xCo2xMn0.5-xO2随着钴含量的增加,材料的充放电容量提高,且循环性能变好：0.2C倍率下、2.7～4.3V的电压范围内,LiNi0.425CO0.15Mn0.425O2的放电比容量为145mAh·g^-1、LiNi0.4CO0.2Mn（0.4）O2为150mAh·g^-1、LiNi1/3Co1/3Mn1/3O2为158mAh·g^-1,循环50周期后LiNi0.425CO0.15Mn0.425O2和LiNi0.4Co0.2Mn0.4O2的容量衰减率在3%以内,LiNi1/3Co1/3Mn1/3O2容量无衰减.交流阻抗测试结果表明,随着钴含量的增加,材料阻抗值减小.     

Ag掺杂CoSb_3材料的制备及其热电性能

采用溶剂热合成再热处理方法制备了AgxCo4Sb12(x=0,0.1,0.2)粉末,粉末经真空熔融处理得到块体试样。用X射线衍射和扫描电镜分别分析了样品的物相和断面显微结构。测试了试样从室温至773K的电导率和Seebeck系数。Ag掺杂的试样Seebeck系数均是正的,呈p-型导电,而未掺杂的试样在T～325K时从n-型转变为p-型。Ag的引入使CoSb3的电导率显著提高,在整个测试范围内其功率因子均比CoSb3的高。而x=0.2的试样其电导率和热电功率因子较其它试样都高,在299K时电导率达到4516S.cm-1,573K时功率因子达到12.3×10-6W.K-2.cm-1。分析认为Ag是以替代Co的形式进入CoSb3晶格,而并非如预计的那样进入CoSb3的结构孔洞。     

低温燃烧法合成Ce1-xNdxO2-x/2（0≤x≤0．6）纳米粉体

采用低温燃烧合成法，在柠檬酸-硝酸盐体系中合成出Ce1-xNdxO2-x/2（0≤x≤0．6）固溶体纳米粉体。X射线衍射（XRD）结果表明，Nd^3＋取代Ce^4＋进入晶格内部，形成具有单相立方萤石结构的固溶体，其晶格常数随Nd^3＋掺杂浓度的增大而线性增加，晶粒尺寸在15-24nm之间。透射电镜（TEM）结果表明，粉体颗粒尺寸在20-40nm之间，分散性较好，具有较高的烧结活性。拉曼光谱（Raman Spectrum）结果表明，F2g宽化峰的出现与掺杂后固溶体中产生的氧空位有关，并且随着掺杂浓度的增加，氧空位数量也再增加。     

固相法制备BaTiO3基细晶陶瓷粉体

通过传统的固相法制备BaTiO3基细晶陶瓷粉体，讨论了在预烧温度和烧结温度相同的情况下，探讨不同施主元素的添加量对陶瓷晶粒及电性能的影响；在预烧温度和烧结温度相同的情况下，探讨不同受主杂质对陶瓷晶粒及电性能的影响；在施、受主掺杂量及烧结温度相同的情况下，探讨不同的预烧温度对陶瓷晶粒及电性能的影响．为了制备高升阻比、晶粒细小的BaTi03陶瓷，选取的材料配方为Ba1.0Ti1.01O3＋0.4％（摩尔分数）Y2O3＋0.03％（摩尔分数）Mn（NO3）2＋2％S102，粉体在1200℃预烧，保温2h，样品在1280℃烧成。上电极后测得常温电阻率为4937Ω·cm，升阻比为7．116×10^3，温度系数为14．03％，居里温度为128．4℃．     

Ag_2Te掺杂对p型Bi_(0.5)Sb_(1.5)Te_3块状合金热电性能的影响

采用真空熔炼、机械球磨及放电等离子烧结技术(SPS)制备得到了(Ag2Te)x(Bi0.5Sb1.5Te3)1-x(x=0,0.025,0.05,0.1)系列样品,性能测试表明,Ag2Te的掺入可以显著改变材料的热电性能变化趋势,掺杂样品在温度为450~550K范围内具有较未掺杂样品更优的热电性能.适当量的Ag2Te掺入能够有效地提高材料的声子散射,降低材料的热导率.在测试温度范围内,(Ag2Te)0.05(Bi0.5Sb1.5Te3)0.95具有最低的晶格热导,室温至575K范围内保持在0.2~0.3W/(m·K)之间,在575K时,(Ag2Te)0.05(Bi0.5Sb1.5Te3)0.95试样具有最大热电优值ZT=0.84,相较于未掺杂样品提高了约20%.     

Pr, Mn多元渗对 BaTiO3陶瓷结构与电性能的影响

采用溶胶-凝胶法制备了纯BaTiO3、Pr,Mn液相掺杂及气相多元扩渗改性的BaTiO3陶瓷.研究结果表明,Pr掺杂能使纯BaTiO3陶瓷的室温电阻率下降为1.01×10^5Ω·m;而Mn掺杂使室温电阻率升高为1.50×10^13Ω·m.但Pr和Mn的气相扩渗都能降低BaTiO3陶瓷的室温电阻率至1.08×10^3Ω·m和1.29×10^5Ω·m.Pr-Mn共渗BaTiO3陶瓷出现了典型的NTC效应.XRD分析表明,Pr或Mn掺杂并不能改变BaTiOa陶瓷的物相结构,但经Pr-Mn共渗后,出现了新化合物BaMn0.12Al1.88O4和Al8Mn4Pr的特征峰.XPS分析表明,气相多元渗使Pr,Mn,C元素都扩渗到陶瓷体内,并使各化学元素之间的结合更加牢固.SEM测试结果表明,Pr,Mn气相扩渗使陶瓷表面明显改观,晶粒生长完整,粒度分布均匀,气孔率下降.     

水热合成锆钛酸铅微晶体的晶粒度分析

采用Ti02，ZrOCl2·8H2O，Pb（NO3）2为原料，KOH为矿化剂，在不同温度、不同KOH浓度、不同反应时间，进行了锆钛酸铅（PZT）微晶体的水热合成实验。结果表明，水热反应温度与KOH浓度大大影响了PZT微晶体的晶粒度和晶体结构，而水热反应时间只影响了PZT微晶体的晶粒度，对晶体结构没有明显影响。在实验条件下水热合成的PZT微晶的晶粒度为10～20nm之间。     

Insertion of triangulated surfaces into a meccano tetrahedral discretization by means of mesh refinement and optimization procedures

In this paper, we present a new method for inserting several triangulated surfaces into an existing tetrahedral mesh generated by the meccano method. The result is a conformal mesh where each inserted surface is approximated by a set of faces of the final tetrahedral mesh. First, the tetrahedral mesh is refined around the inserted surfaces to capture their geometric features. Second, each immersed surface is approximated by a set of faces from the tetrahedral mesh. Third, following a novel approach, the nodes of the approximated surfaces are mapped to the corresponding immersed surface. Fourth, we untangle and smooth the mesh by optimizing a regularized shape distortion measure for tetrahedral elements in which we move all the nodes of the mesh, restricting the movement of the edge and surface nodes along the corresponding entity they belong to. The refining process allows approximating the immersed surface for any initial meccano tetrahedral mesh. Moreover, the proposed projection method avoids computational expensive geometric projections. Finally, the applied simultaneous untangling and smoothing process delivers a high‐quality mesh and ensures that the immersed surfaces are interpolated. Several examples are presented to assess the properties of the proposed method.     

Certification Institutions Expected to Update and Transfer Information on Present Standards

Standards are the basis for production enterprises to organize production, ex-factory inspection, trade (delivery) and technical exchanges, product certification, quality arbitration and supervision.……     

From Industry 4.0 to Research 4.0. Development of High Performance Fibers in the Light of Digitization

We associate a variety of innovations with the term ＂Industry 4.0＂. The pioneer of many 4.0 modifications forms the basisfor the trend towards the integrated di...     

Flow calorimeter for enthalpy increment measurements on condensed gases

A flow calorimeter for enthalpy increment measurements on condensed gases is presented. A better knowledge of the properties of the liquefied natural gas is needed, and therefore a liquid loop has been designed for our flow calorimeter. The fluid loop in the calorimeter is designed in order to avoid the two-phase region, since two phases would give compositional disturbances in the measurements. The avoidance of the two-phase region is made possible by increasing the pressure of the test fluid after the measurement section, then heating the fluid at super-critical pressure past the critical point. Finally, the fluid is throttled to the low-pressure gas state at the inlet condition of the compressor that circulates the fluid. To perform the pressure increase, a new cryogenic pump has been designed. To evaluate the new equipment, measurements were taken on liquid ethane over the temperature range 146–256 K at pressure between 0.9 and 5.1 MPa.     

Refrigerators Enter a New Era of Health Preservation Frestech initiates the establishment of China's first standard for household sterilization refrigerators

On November 30, 2007, the China Association for Standardization (CAS) held a press conference at Beijing Diaoyutai State Guest House. Leaders from the China Household Electric Appliance Research Institute, the China Household Electric Appliance Association, and the China Consumers' Association attended and made speeches.……     

Optimum-Simulation von Ernteprozessen

Zusammenfassung Bei der Gestaltung von Ernteprozessen — beispielsweise des Prozesses Mähdrusch, Körnertransport und -abnahme — als transportverbundene Fließarbeitsverfahren mit mindestens zwei verschiedenen Arbeitsmitteln gibt es einen großen Optimierungsspielraum. Solche Prozesse sind mehrstufige Bedienungsprozesse mit gemischter Anordnung der Bedienungseinrichtungen. Außerdem besitzen sie stark ausgeprägte räumliche Aspekte. Es wird vor allem gezeigt, welche Merkmale solcher Prozesse in Simulationsmodellen abgebildet sein müssen, welche Zielgrößen in Abhängigkeit von welchen Einflußgrößen unter Berücksichtigung welcher Prozeßbedingungen ermittelt werden sollten und wie der Bewertungsprozeß zur Ermittlung der gewünschten Informationen gestaltet werden muß.     

Roman iron and steel: A review

ABSTRACT

The production of ferrous metal increased during the Roman Late Republican period, Principate and Empire. The direct bloomery process was used to extract the metal from its ores using slag-tapping and slag-pit furnaces. The fuel was charcoal and an air blast was introduced by bellows-operated tuyères. Iron formed as a bloom, often as a spongy mass of metal, which contained impurities from the smelting process, including unreacted ore, fuel, slag and fragments from the furnace walls, while the metal was often inhomogeneous with varied carbon contents. Blooms were either smithed directly into bars or ingots or they were broken up, which also allowed the removal of gross impurities and a selection of pieces with similar properties to be made. These could then be forge-welded together and formed into characteristically shaped ingots. Making steel in the furnace seems to have been achieved: it depended on the ore and the furnace and conditions within it. Surface carburization was also carried out. Iron and steel were used extensively in construction and for tools and weapons. Fire welding was often used to add pieces of steel to make the edges of tools and weapons, which could be heat-treated by quenching to harden them.     

A study of centrifugal cast high boron high speed steel

In the present study a high‐boron high speed steel (HSS) roll material was designed. Many expensive alloy elements have been substituted by cheap boron alloy, and high‐boron high speed steel roll has been manufactured by centrifugal casting method. The microstructures, mechanical properties and wear resistance of centrifugal casting high‐boron high speed steel roll have been investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X‐ray diffraction (XRD) analysis, hardness test, impact test and wear test. The results indicated that the solidification microstructures of high‐boron high speed steel roll consisted of M₂(B,C), (W,Mo)₂(B,C), M₃(B,C), M₂₃(B,C)₆ type borocarbides and martensite, a small amount of retained austenite. Borocarbides were continuously distributed over the grain boundary. After quenching from 1050 °C, local broken network appeared in partial borocarbides, and fine secondary borocarbide precipitated from the matrix. After tempering from 525 °C, the amount of precipitated borocarbide increased significantly. After heat treatment, the hardness of high‐boron high speed steel roll excelled 60 HRC, and its impact toughness excelled 8.0 J/cm². The single groove steel rolling amount of high‐boron high speed steel rolls increases by 500% than that of bainite cast iron roll, when the rolls are used in K₁ mill housing of bar mill.     

Thixotropy of Systems with Shear Thinning and Plastic Flow Behavior

The definition of the thixotropy is a decrease in viscosity with time in shear and a subsequent recovery of viscosity after the shear deformation is removed.We ...