Na和Al双掺杂P型Bi0.5Sb1.5Te3热电材料的制备及性能研究

采用真空熔炼及热压烧结技术制备了Na和Al双掺杂P型Bi0.5Sb1.5Te3热电材料。利用X射线衍射(XRD)、扫描电子显微镜(SEM)对样品的物相结构和表面形貌进行了表征。XRD分析结果表明,Na0.04Bi0.5Sb1.46-x Al x Te3块体材料的XRD图谱与块体材料Bi0.5Sb1.5Te3的图谱完全对应,所有块体材料的衍射峰均与衍射卡JCPDS 49-1713对应,这表明Na和Al元素已经完全固溶到Bi0.5Sb1.5Te3晶体结构中,形成了单相固溶体合金。SEM形貌表明材料组织致密且有层状结构特征。Na和Al双掺杂提高了Bi0.5Sb1.5Te3在室温附近的Seebeck系数。在Na掺杂量为0.04时,同时Al掺杂量由x=0.04增加至0.12,电导率逐渐降低,在实验掺杂浓度范围内,Na和Al双掺杂会使P型Bi0.5Sb1.5Te3材料的电导率受到较大的损失。在300~500 K时,通过Na和Al部分替代Sb,Na0.04Bi0.5Sb1.42Al0.04Te3和Na0.04Bi0.5Sb1.38Al0.08Te3样品的热导率均有不同程度地减小,在300K时双掺杂样品Na0.04Bi0.5Sb1.42Al0.04Te3的最大ZT值达到1.45。     

纳米颗粒Ag2Te掺杂p-(Ag2Te)x(Bi0.5Sb1.5Te3)1-x的快速热压制备和热电性能表征

通过溶剂热法制备出六方相Bi2 Te3纳米粉体,采用真空封管熔炼法得到Sb掺杂的Bi0.5Sb1.5Te3合金.采用溶剂热法合成粒度为40 nm的Ag2 Te纳米粉体,并通过高能球磨工艺将其掺入Bi0.5Sb1.5Te3合金,从而得到p-(Ag2 Te)x(Bi0.5 Sb1.5 Te3)1-x合金(x为Ag2 Te摩...     

日盲紫外光电阴极用碲合金蒸发材料研究

选择铋作为合金化元素,利用真空熔炼慢速凝固方法制备出Te60Bi40(%,质量分数)合金来代替纯碲作为日盲光电阴极的碲蒸发源。利用光学显微镜(OM)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)以及能谱仪(EDS)等方法对制备的Te60Bi40合金样品进行了微观组织观察,对合金的相组成、相结构以及各相的成分进行了分析。结果表明:利用真空熔炼慢速凝固方法制备的Te60Bi40合金由初晶Bi2Te3和共晶(Bi2Te3+Te)相组成,得到了近平衡相。初晶Bi2Te3晶粒为粗大的板条状,板条平均宽度为300μm,晶界较平直有棱角,呈现小平面相特征。共晶Bi2Te3相以片条状的形态均匀分布在共晶Te相中。在共晶凝固过程中,由于共晶Bi2Te3相和Te相的热导率和熔化潜热有较大的差异,Te相在凝固时作为领先相生长,滞后相Bi2Te3最终被领先相Te相完全包裹。初晶Bi2Te3相和共晶Bi2Te3相中Te的质量分数分别为49.2%和49.6%,共晶Te相中Te的质量分数接近100%。     

N型(Bi_2Te_3)_(0.9)(Ag_xBi_(2-x)Se_3)_(0.1)热电材料的快速热压法制备及性能表征

采用水热法制备平均粒度约300 nm的六方相Bi2Te3纳米粉末.再以Bi2Te3粉末为原料,采用封管熔炼法制备N型(Bi2Te3)0.9(AgxBi2-xSe3)0.1(x为Ag的摩尔分数.x=0.1,0.2,0.3,0.4)合金粉体材料,通过快速热压制备N型(Bi2Te3)0.9(AgxBi2-xSe3)0.1块状热电材料.在300～550 K温度范围内研究该材料的热电性能与Ag掺杂量之间的关系,以及热压工艺对材料热电性能的影响.结果表明在775 K,40 MPa条件下烧结20 min后材料的相对密度达到97%以上,晶粒大小在3岬左右.当Ag掺杂量x=0.2时,在300 K温度下热导率达到最小值0.71 W/mK,同时获得最高的热电优值(ZT值)1.07.     

原子荧光光谱法在金属材料分析中的研究进展

原子转光光谱法在测定As、Hg、Bi、Sb、Se、Te、Ge、Sn、Pb、Zn、Cd、Cr（Ⅵ）十二种痕量水平元素方面有独特的优势。本文结合近年来原于荧光光谱法在金属材料的痕量元素分析中的研究应用情况做一论述。     

Bi_2Te_3基制冷晶棒加工废粉料的回收与热电性能的优化

针对半导体制冷行业P型Bi_2Te_3基制冷晶棒的生产与加工过程中产生的废粉料,经过真空煅烧、1次熔炼及2次熔炼除去粉料中的杂质,获得Bi_2Te_3基粉末,然后加压烧结,制备P型Bi_2Te_3基块体材料,测定材料的热电性能,并通过在除杂后的Bi_2Te_3基粉末中加入单质Sb和Te,进行成分优化。结果表明,废粉料的回收率达到85.73%以上,采用废粉料制备的P型块体Bi0.53Sb1.3Te3合金在室温下的电导率仅为331.79 S/cm,热电优值为0.75。在除杂后的废粉料中加入单质Sb和Te后制备的Bi0.36Sb1.64Te3合金在室温下的电导率达到970 S/cm,热电优值为1.13,350 K下的热电优值为1.23,并且在300~470 K温度范围内的热电优值都超过1.0,性能超过了采用高纯原材料生产的P型区域熔炼产品,能够满足生产企业的要求。     

MnP_(1-x)M_x系列合金的磁热效应

研究了1∶1型MnP基系列合金MnP1-xMx(M=Si,Sb,Ge,Zn,Sn)(x=0,0.1)的结构及其磁热效应。室温X射线衍射表明该系列合金的主相结构均为正交MnP结构,空间群为Pnma。在用Ge,Sb,Zn,Sn作为替代元素的合金中存在少量第二相Mn5.64P3。磁性测量表明该系列合金MnP1-xMx(M=Si,Sb,Ge,Zn,Sn)(x=0,0.1)的存在由铁磁-顺磁的二级相变。其居里温度Tc分别为286,295,294,295,295K。通过磁化曲线计算了MnP1-xMx(M=Si,Sb,Ge,Zn,Sn)(x=0,0.1)合金的最大等温磁熵变-ΔSm,均在0.7～1.3J.kg-.1K-1之间。     

CdS/CdS和CdS/Dy/CdS薄膜结构及其XPS分析

采用化学水浴法制备了结构为CdS/CdS的薄膜,并结合电子束真空蒸发法,在两层CdS之间沉积一层Dy单质制备了结构为CdS/Dy/CdS的Dy掺杂薄膜。XRD和SEM测试表明,未掺杂的薄膜为沿(111)晶面择优生长的立方相闪锌矿结构,但是含有Dy掺杂层的CdS薄膜则为立方相和六方相的混合结构,并且掺Dy后CdS的晶粒尺寸和晶格常数变大。XPS分析表明,两种样品均富Cd,掺Dy有助于降低薄膜中O和C的含量,进而抑制薄膜中氧化物的形成;未掺杂时薄膜表面和内部Cd、S的原子比分别为1∶0.63和1∶0.71,掺Dy后分别提高到1∶0.81和1∶0.83,更接近CdS的化学计量比,而且组分更加均匀。     

真空电弧等离子体合成(BixSb1-x)2Te3纳米粉末材料

以单质Bi,Sb和Te粉末为原材料,通过真空电弧等离子体蒸发法合成了(Bi<,x>Sb<,1-x>)<,2>Te<,3>热电粉末材料.采用X射线衍射(XRD)、能谱分析(EDS),场发射扫描电子显微术(FE-SEM),透射电子显微术(TEM)和选区电子衍射(SAED)分析方法对(Bi<,x>Sb<,1-x>)<,2>Te<,3>粉末材料的物相结构、成分和形貌进行了表征.XRD图谱的3强衍射峰分别为(015),(1010)和(110),(Bi<,x>Sb<,1-x>)<,2>Te<,3>纳米粉末的XRD图谱与标准XPD图谱峰(49-1713)相对应,宽化的衍射峰表明了粉末的晶粒具有纳米尺度.能谱定量分析表明Bi和Sb的原子百分比分别为18.1%,20.3%,两者原子百分比之和为38.4%,Te的原子百分比是61.6%.场发射扫描电子显微分析表明纳米粉末颗粒尺寸比较均匀,粉末存在团聚现象,大多数粉末都呈椭球形.透射电子显微分析表明(Bi<,x>Sb<,1-x>)<,2>Te<,3>纳米粉末的平均粒径约为50 mm,粉末呈不规则的多面体结构,还有一些薄片状和棒状的结构,这与Bi<,2>Te<,3>基半导体化合物的高度各向异性是一致的.(Bi<,x>Sb<,1-x>)<,2>Te<,3>纳米粉末的选区电子衍射图表明每一个颗粒是由许多小晶核组成的,证明了颗粒是以纳米尺度生长.由于晶粒取向随机,且晶粒细小引起有许多衍射斑组成的衍射环的宽化,揭示了(Bi<,x>Sb<,1-x>)<,2>Te<,3>纳米粉末的多晶结构.     

粉末冶金法制取热电材料

热电材料碲化铋 (Bi2Te3)合金 ,工作温度接近 4 5 0℃ ,可用于制造家用冰箱、空调机、小型探测仪及传感器等。碲化铋可与少量碲化锑 (Sb2 Te3)合金化形成P型半导体固溶体 ,与少量硒化铋(Bi2 Se3)合金化形成N型半导体固溶体。碲化铋、它与其它组分形成的合金都具有高度各向异性的六方结构。拉制碲化铋合金单晶最常用的方法是定向结晶法。可是这种方法生产率低 ,组织偏析 ,且力学性能差。加拿大经过三年研制 ,开发出一种通过粉末冶金途径制造碲化铋合金的方法。它是将直径为 2～ 5mm的粒状纯元素 (Bi,Te ,Se ,Sb等 )粉在球磨机中进行机械…     

CaO—SiO2—Na2O—CaF2—Al2O3—MgO保护渣系的Al2O3吸收速率和粘度

采用CaO-SiO2-Na2O-CaF2-Al2O3-MgO渣系,通过测定熔渣的粘度和Al2O3吸收速率,研究连铸保护渣的Al2O3吸收速率与粘度及化学成分之间的关系。在一定条件下,当CaO/SiO2为1.2左右时,粘度达到最小值,Al2O3吸收速率达到最大值,分别为0.10?Pa*s、8.403×10-4?kg*m-2*s-1。随着渣中Na2CO3含量、CaF2含量和MgO含量的增加,粘度减小,Al2O3吸收速率增大。随着渣中Al2O3含量的增加,粘度增大,Al2O3吸收速率减小。粘度为Al2O3吸收速率的主要控制因素。随着熔渣粘度的增加,连铸保护渣的Al2O3吸收速率逐渐减小。     

Kinetics of reduction of ferric iron in Fe2O3-CaO-SiO2-Al2O3 slags under argon, CO-CO2, or H2-H2O

The rates of reduction of ferric iron in Fe₂O₃-CaO-SiO₂-Al₂O₃ slags containing 3 to 21 wt pct Fe₂O₃ under impinging argon, CO-CO₂, or H₂-H₂O have been studied at 1370 °C under conditions of enhanced mass transfer in the slag using a rotating alumina disc just in contact with the slag surface. For a 6 wt pct Fe slag at a stirring speed of 900 rpm the observed reduction rates by 50 pct H₂-H₂O were a factor of 2 to 3 times higher than those by 50 pct CO-CO₂ and more than one order of magnitude higher than those under pure argon. The observed rates were analyzed to determine the rate-controlling mechanisms for the present conditions. Analysis of the rate data suggests that the rates under 50 pct H₂-H₂O are predominantly controlled by the slag mass transfer. The derived values of the mass-transfer coefficient followed a square-root dependence on the stirring speed for a given slag and, at a given stirring speed, a linear function of the total iron content of the slags. The rates of oxygen evolution during reduction under pure argon were shown to be consistent with a rate-controlling mechanism involving a fast chemical reaction at the interface and relatively slow mass transfer in the gaseous and the slag phases. The rates of reduction by CO-CO₂ (pCO=0.02 to 0.82 atm) were found to be likely of a mixed control by the slag mass transfer and the interfacial reaction. A significant contribution of oxygen evolution to the overall rates was observed for more-oxidized slags and for experiments with relatively low values of pCO. Assuming a parallel reaction mechanism, the estimated net reduction rates due to CO were found to be of the first order in pCO, with the first-order rate constants being approximately a linear function of the ferric concentration. This article is based on a presentation made in the “Geoffrey Belton Memorial Symposium” held in January 2000, in Sydney, Australia, under the joint sponsorship of ISS and TMS. The original symposium appeared in the October 2000 Vol. 31B issue.     

Al2O3La2O3Y2O3/Cu复合材料的电弧侵蚀特性研究

采用喷射沉积和内氧化法制备出Al₂O₃La₂O₃Y₂O₃/Cu复合材料,研究该材料在直流20 V/20 A的工作条件下触点的电弧侵蚀特性,并与Al₂O₃/Cu材料进行了对比分析.利用电子天平、扫描电镜等方法分析电弧侵蚀后触点的质量变化和表面微观结构.结果表明,通过添加Y₂O₃、La₂O₃稀土氧化物颗粒,可有效降低触头材料的材料转移量.Al₂O₃La₂O₃Y₂O₃/Cu材料的抗熔焊性和抗烧损性优于Al₂O₃/Cu材料的性能.在直流阻性负载条件下Al₂O₃La₂O₃Y₂O₃/Cu阳极触头表面形成凹坑,阴极触头表面形成凸起,触点表面显示出浆糊状凝固物和喷发坑等电弧侵蚀形貌特征.      

CaO-La2O3-B2O3-Eu2O3转光玻璃的合成及荧光性质

X射线衍射研究表明CaO-La2O3-B2O3-Eu2O3体系的玻璃化温度在1025℃附近.荧光光谱和ESR谱研究表明,在CaO-La2O3-B2O3-Eu2O3玻璃体系中存在着Eu2+和Eu3+两种价态离子. 316, 360, 379, 394, 413, 462和532nm锐线激发峰和592,616和650红区发射峰分别对应Eu3+的f-f激发跃迁和5D0-7FJ (J=1,2,3)跃迁发射;351nm和427nm宽带激发峰和蓝区发射分别对应Eu2+的5d-4f激发跃迁和发射.     

Effects of La2O3/Li2O/TiO2- Coating on Electrochemical Performance of LiCoO2 Cathode

Conventional cathode material （LiCoO2） was modified by coating with a thin layer of La2O3/Li2O/TiO2 for improving its performance for lithium ion battery. The morphology and structure of the modified cathode material was characterized by SEM, XRD, and Auger electron spectroscopy. The performance of the cells with the modified cathode material was examined, including the cycling stability, the diffusion coefficient under different voltages, and the C-rate discharge. The results showed that the cell composed of the coated cathode material discharged at a large current density, and possesses a stable cycle performance in the range from 3.0 to 4.4 V. It was explained that the rate of Li ion diffusion increased in the cell while using La2O3/Li2O/TiO2-coated LiCoO2 as the cathode and the coating layer may act as a faster ion conductor （La2O3/Li2O/TiO2）.     

Water and solute activities of the solution systems of H2So4-Cuso4-H2O and Hci-Cuci2-H2O

The activities of water, α(H₂O), in the solution system of H₂SO₄-CuSO₄-H₂O were determined by an isopiestic method and those in the solution system of HCl-CuCl₂-H₂O by a transpiration method, both at 298 K. The activities of H₂SO₄ and H⁺ in the solution system of H₂SO₄-CuSO₄-H₂O were also determined at 298 K by the emf method. The water activities in both systems obeyed the Zdanovskii rule relatively well. The α(H₂O) experimentally determined in the sulfate system showed a satisfactory agreement with those calculated from the Robinson-Bower equation, assuming the complete dissociations of H₂SO₄ and CuSO₄, whereas a good agreement between the calculated and experimentally determined α(H₂O) for the chloride system was obtained when the formation of Cu(II) chloro-complexes was taken into consideration. The mean activity coefficients, γ_±, of solutes, including H₂SO₄, HC1, and CuCl₂ in these solution systems, were calculated at 298 K by the McKay-Perring method using the activity data. The γ_±(H₂SO₄) values in the solution system of H₂SO₄-CuSO₄-H₂O were in good agreement with those determined by the emf method. On the other hand, the γ_±(CuSO₄) were calculated at the same temperature based upon the Gibbs-Duhem equation using both measured α(H₂O) and calculated γ_±(H₂SO₄) values, because of solubility limitations.     

CaO含量对CaF2-Al2O3-CaO-Ce2O3渣系中Ce2O3行为的影响

在Fe-Cr-Al合金中添加微量的稀土元素可显著改善合金的使用性能, 文中以电渣重熔生产Fe-Cr-Al合金所用稀土渣为研究对象, 根据离子-分子共存理论(IMCT)建立了1 823 K时CaF₂-Al₂O₃-CaO-Ce₂O₃四元渣系热力学质量作用浓度模型.结果表明:当渣系中CaO和Al₂O₃的质量百分数之比维持在1:1, 即w_CaO /w_Al2O3=1时, 随着Ce₂O₃含量增加, 渣中铈铝酸盐Ce₂O₃·Al₂O₃质量作用浓度(活度)显著增加, 但炉渣物相种类没有变化.渣系中Ce₂O₃含量分别在10 %, 20 %, 30 %, 40 %时, w_CaO /w_Al2O3值对组元活度的影响各不相同但有共同特征, 表现在处于约1.0~1.8时, CaO活度增加最迅速, Ce₂O₃活度增加, Ce₂O₃·Al₂O₃活度下降, 说明渣中CaO含量增加促进了Ce₂O₃·Al₂O₃分解而导致Ce₂O₃活度增加, 选取渣系进行熔融和X射线衍射实验, 用jade 5.0软件分析物相, 实验结果与计算一致.      

Synthesis of ZrO2-HfO2-Y2O3-Sc2O3 Nano-Particles by Sol-Gel Technique in Aqueous Solution of Alcohol

Zirconium dioxide is a significant material withgood physicochemical characteristics . It is used inmanyfields such as energysources ,material and envi-ronment . Cubic phase zirconium dioxide doped withyttria (YSZ) is alreadyin wide use in solid oxygenfu-…     

SnCl2－HgCl2－K2Cr2O7容量法测定的矿石中TFe时HgCl2用量的选择

为了保持应用已久的有汞测铁经典方法中的许多优点而减轻HgCl2对环境的污染的缺点,对方法中HgCl2的用量由5m^[1]减少为2ml进行理论上的探讨,并以试验结果加以论证。     

CaO--TiO2--Fe2O3三元系中Ca3TiFe2O8的生成机理

钒钛磁铁矿是烧结矿重要的原料之一,Ca₃TiFe₂O₈作为钒钛烧结矿中矿物被发现之后,其生成机理尚不明确.本文采用X射线衍射分析、元素能谱分析和TG-DSC分析相结合的方法,研究了Ca₃TiFe₂O₈的生成机理以及不同温度、CaO与TiO₂含量下Ca₃TiFe₂O₈的生成规律.实验结果表明,Ca₃TiFe₂O₈由Ca₂ Fe₂O₅和CaTiO₃反应生成,即CaO和Fe₂O₃反应生成Ca₂ Fe₂O₅;其后,与CaTiO₃反应生成Ca₃TiFe₂O₈.反应时间越长,Ca₃TiFe₂O₈的生成量越大,但反应温度对Ca₃TiFe₂O₈生成的影响并不明显.另外,还发现CaO含量越高,Ca₃TiFe₂O₈越易于生成,而且等摩尔Fe₂O₃和CaO下只要存在TiO₂,就会有Ca₃TiFe₂O₈生成.