溶胶凝胶法制备Li4.5B0.5Si0.5O4-xLi2O导体材料及导电性能

采用溶胶－凝胶法制备了Ｌｉ４．５Ｂ ０．５Ｓｉ０．５Ｏ４－ｘＬｉ２Ｏ（ｘ＝０～０．５）离子导体材料,并采用ＤＴＡ－ＴＧ、ＸＲＤ、ＴＥＭ及交流阻抗等技术对样品进行了分析和测试,结果发现：溶胶－凝胶法可降低Ｌｉ４．５Ｂ０．５Ｓｉ０．５Ｏ４的合成温度;随Ｌｉ２Ｏ的掺入可增强基质材料的致密性并提高其离子的导电性能。     

熔甩Cu—Co合金薄带的结构,磁性及巨磁阻

研究了熔甩法制备的ＣｏｘＣｕ１－ｘ（０〈ｘ〈０．２０）颗粒合金的结构、磁性以及输运性质，通过Ｘ射线衍射（ＸＲＤ），差动热分析（ＤＣＳ）以及磁性测量，发现造成Ｃｏ－Ｃｕ合金磁性及输运性质变化的Ｃｏ相分离过程，当０〈ｘ〈０．１５时，在４５０℃退火火３０ｍｉｎ的ＣｏＣｕ合金中Ｃｏ颗粒的直径为３．５－４．５ｎｍ。并呈现最大的巨磁阻效应，磁性随析出Ｃｏ颗粒浓度及尺寸的变化与双通道模型的预示一致，粒子界面引起     

定向凝固Tb0.3Dy0.7（Fe,M）1.95超磁致伸缩合金微观缺陷的研究

研究了经超高温梯度向凝固制备的Ｔｂ０．３Ｄｙ０．７（Ｆｅ，Ｍ）１．９５合金样品中存在的晶体缺陷的类型，分析其对该材料磁致伸缩性能的影响，探讨如何调整工艺来消除晶体缺陷，提高材料的磁致伸缩性能。     

稀土正硼酸盐Ln_(1-x)BO_3:Eu_x(Ln=Y,Gd)的结构与发光特性

用溶胶－凝胶法和高温固相反应分别制备了纳米量级和常规尺度的稀土正硼酸盐荧光粉ＬｎＢＯ３：Ｅｕ（Ｌｎ＝Ｙ,Ｇｄ）,测量了它们的激发光谱并首次观察到了ＹＢＯ３：Ｅｕ中Ｅｕ３＋的７Ｆ０→５Ｄ０跃迁的 Ｎｅｐｈｅｌａｕｘｅｔｉｃ效应．根据低温下的激发光谱,发射光谱以及变温条件对发光光谱的影响,ＹＢＯ３中Ｌｎ３＋所占据的两种格位的对称性被修正为Ｃ３和Ｄ３在不同方法制备的样品中观察到了不同的发光强度和猝灭浓度,缺陷的影响是产生这种不同的原因,退火样品的发光和拉曼散射谱的变化反映出掺杂的杂质Ｅｕ３＋的团聚化是可能的缺陷来源．     

超磁致伸缩材料Tb_（0．27）Fe_（2－x）的超声学研究

用超声脉冲回波重迭法测量了超磁致伸缩材料Ｔｂ＿（０．２７）Ｄｙ＿（０．７３）Ｆｅ＿（２－ｘ）系列样品在不同磁场下的超声波速度，给出了该系列样品的弹性常数随磁场的变化情况，并对实验结果作了初步的解释和探讨。     

Sr0.4Pb0.6TiO3基陶瓷晶界组成对热敏特性的影响

采用固相烧结工艺制备出了Ｓｒ_０．４Ｐｂ_０．６ＴｉＯ_３半导体陶瓷元件,其阻温特性具有独特的ＮＴＣＲ和ＰＴＣＲ复合效应,陶瓷室温电阻率及居里点以下的ＮＴＣＲ效应随着烧结温度的升高而提高,适当过量ＰｂＯ则能降低陶瓷室温电阻率及其ＮＴＣＲ效应．利用ＸＲＤ、ＳＥＭ和ＥＤＳ分别对样品的相结构、形貌及成份分布等进行分析,结果显示晶界中的Ｓｒ,Ｔｉ含量相对较高,而Ｐｂ含量相对较低,材料的阻温特性明显受其影响．铅挥发造成的阳离子空位是该类半导体陶瓷在居里点下出现ＮＴＣＲ效应的主要原因之一,同时探讨了Ｙ^３＋离子掺杂（Ｓｒ,Ｐｂ）ＴｉＯ_３陶瓷的半导化机理和热敏特性．     

(Ce_(0.67)Tb_(0.33))MgAl_(11)O_(19)荧光粉的溶胶-凝胶法合成及发光性能

采用溶胶凝胶法合成（Ｃｅ０．６７Ｔｂ０．３３）ＭｇＡｌ１１Ｏ１９绿色荧光粉。利用ＴＧ－ＤＴＡ和ＸＲＤ等实验技术，研究了荧光粉的形成过程，找出了最佳合成条件，并对其粉体形貌和发光性能进行研究。结果表明，用溶胶凝胶法合成的（Ｃｅ０．６７Ｔｂ０．３３）ＭｇＡｌ１１Ｏ１９是一种性能优良的荧光粉。     

Sc2O3稳定的ZrO2超细粉的制备与烧结

本文用化学共沉淀法制备了Ｓｃ２Ｏ３稳定的ＺｒＯ２纳米超细粉。用ＸＲＤ，ＴＥＭ，ＳＥＭ以及ＢＥＴ测比表面等方法分析了粉体和烧结体的相组成的显微结构及其性能。实验结果表明６．０、７．８、９．６ｍｏｌ％Ｓｃ２Ｏ３掺杂量的粉体易于烧结，而３．５、１２．０ｍｏｌ％Ｓｃ２Ｏ３掺杂量的粉体则不易烧结，原因在于样品冷却过程中相变引起的体积变化以及烧结体中双重显微结构的存在。     

溶胶—凝胶法制备锆酸锂陶瓷微球

采用溶胶－凝胶法制备出了粒径小于１ｍｍ的陶瓷微球。微球直径分布在０．４￣１．０ｍｍ，密度达８０￣９０％Ｔ．Ｄ．，比表面积为１８￣３２ｍ＾２／ｇ，压碎强度达１￣３ｋｇ／个球。该工艺克服了金属的氢氧化物难以沉淀的困难，并可推广到其他材料的制备。     

溶胶-凝胶法PLT薄膜的形成与热处理温度关系研究

利用溶胶－凝胶法合成了透明溶胶和白色稳定乳浊液两种前驱体,通过Ｄｉｐ－ｃｏａｔｉｎｇ方法分别利用掺入及不掺入同配方的晶体微粉的这两种前驱体制备了Ｐｈ_０．９Ｌａ_０．１５ＴｉＯ_３ 薄膜,并通过 Ｘ射线衍射（ＸＲＤ）;扫描电子显微镜（ＳＥＭ）和介电常数测试等手段进行了形成特性研究和比较．结果显示,利用白色乳浊液前驱体制备的Ｐｂ_０．９　Ｌa_０．１５ＴｉＯ_３ 薄膜,其最初形成钙钛矿相的温度比利用透明溶胶制备的同样薄膜的温度降低约４０～５０℃;利用透明溶胶前驱体制备的Ｐｂ_０．９Ｌａ_０．１５ＴｉＯ_３薄膜在热处理温度高到约５７５℃时,钙钛矿相的晶格常数相应下降;约在５２５℃热处理时,薄膜居里温度出现在室温附近;较高的热处理温度时,薄膜中形成的钙钛矿相中Ｌａ的固溶度相对较小,反之则Ｌａ的固溶度较高．     

大尺寸Y:PbWO4晶体的坩埚下降法生长与光学均匀性研究

报道了大尺寸Ｙ：ＰｂＷＯ_４晶体的坩埚下降法生长工艺,讨论了影响晶体生长的主要 因素．探讨了消除晶体开裂、抑制晶体组分过冷的工艺措施,成功地生长出无宏观缺陷的大尺 寸Ｙ：ＰｂＷＯ_４晶体,尺寸达５２ｍｉｎ×５２ｍｍ×２５０ｍｍ．同时,对实验样品沿晶体生长方向不同部 位的横向透过率及发射光谱进行了测试,结果表明,坩埚下降法生长的大尺寸Ｙ：ＰｂＷＯ_４晶体 具有较好的光学均匀性．     

大尺寸Y:PbWO4晶体的坩埚下降法生长与光学均匀性研究

报道了大尺寸Ｙ：ＰｂＷＯ４晶体的坩埚下降法生长工艺，讨论了影响晶体生长的主要 因素．探讨了消除晶体开裂、抑制晶体组分过冷的工艺措施，成功地生长出无宏观缺陷的大尺 寸Ｙ：ＰｂＷＯ４晶体，尺寸达５２ｍｉｎ×５２ｍｍ×２５０ｍｍ．同时，对实验样品沿晶体生长方向不同部 位的横向透过率及发射光谱进行了测试，结果表明，坩埚下降法生长的大尺寸Ｙ：ＰｂＷＯ４晶体 具有较好的光学均匀性．     

Alloy formation in the Fe-Ni system during cold mechanical activation by pressure shear

Binary alloys of the Fe-Ni system were used to study the regularities involved in the cold mechanical synthesis realized by pressure shear in Bridgman anvils. The alloy formation was found to depend on the crystal lattice symmetry: the solid solution is formed in mixtures of components having a similar symmetry of the crystal lattice but the alloy formation is retarded or does not occur altogether in mixtures of components having different symmetries of the crystal lattice. The kinetics of the alloy formation in mixtures of Fe-Ni solid solutions with a FCC lattice was determined. The phase transformations were found to affect the kinetics and the alloy formation mechanism in mixtures whose components are pressure- and strain-unstable.     

Mosaic structure and reflectivity of an as grown copper single crystal using neutron diffraction

A single crystal of copper of size 80 mm dia. and 50 mm length was grown by the Bridgman method. Neutron diffraction investigations were carried out to determine the mosaic spread and reflectivity of this as grown crystal. The crystal was found to be of good quality having structure free and symmetric rocking curves with mosaic spread of 14 min.arc and reflectivity of ∼ 50%.     

高温相偏硼酸钡单晶的下降法生长

采用坩埚下降法生长出了新型双折射晶体高温相偏硼酸钡α-BaB₂O₄单晶,尺寸为φ25mm×100mm,在He-Ne激光照射下无散射颗粒和生长条纹,在可见光区用复式宝石折射仪粗略测得该晶体的双折射率△n≈0.13,在200～900nm光区的透过率>80％.简要介绍了晶体生长的一些基本参数.     

GaSe晶体的掺S生长及性能研究

当生长掺S的GaSe单晶时, 熔体的强烈对流和溶质扩散使得生长出大尺寸的晶体较为困难。本实验采用改进的Bridgman炉, 并结合坩埚旋转技术, 成功生长出了较大尺寸的GaSe_0.89S_0.11单晶体(ϕ20×60 mm³)。采用X射线粉末衍射仪、能谱仪、纳米压痕仪和傅里叶红外光谱仪测量其结构、成分、机械和光学性质。测试结果表明, 质量分数为2.38%的 S掺杂的GaSe晶体(GaSe_0.89S_0.11)没有发生结构相变; 它的机械性能得到了明显的改善, 同时光学性能也得到了一定的提高。     

A study on yttrium doping in lead tungstate crystals

In this paper we present results of a study on the yttrium doping in lead tungstate crystals. The crystal growth by modified Bridgman method is described. Results of trace analysis on raw materials and crystals are presented. The segregation coefficient of yttrium ions in lead tungstate crystals was determined. The scintillation emission and longitudinal transmittance spectra, light output, decay kinetics, light response uniformity and radiation damage were measured. It is found that yttrium doping suppresses slow scintillation component and improves radiation hardness of lead tungstate crystals.     

ZnO晶体生长新方法研究

基于ZnO-PbF₂高温溶液体系的相关系和析晶行为, 发展了一种通气诱导成核的助熔剂-坩埚下降法生长技术. 通过优化生长参数, 获得了尺寸为φ25mm×5mm的ZnO晶体. 该晶体具有纤锌矿结构, 晶格常数a=0.3252nm, b=0.5209nm. X射线定向确认其择优取向生长方向为[0001]. 实验结果表明, 助熔剂-坩埚下降法是ZnO晶体生长的一条新途径.     

碲铟汞晶体制备及其热稳定性研究

以高纯Hg、In、Te单质为原料,通过元素直接化合反应合成了碲铟汞(MIT)多晶料,并利用合成的高纯多晶料,在特殊设计的坩埚中,采用垂直Bridgman法通过自发成核方式成功地生长了尺寸为Φ15mm×175mm的MIT单晶体.利用X射线粉末衍射技术对MIT晶体结构及物相进行的分析表明,所获得的晶体是单相的MIT晶体,为缺陷闪锌矿结构,空间群为F43m.采用高分辨X射线衍射仪测量了所生长MIT晶体的摇摆曲线,结果表明所得晶体完整性较好,为高质量的单晶体.对所生长的MIT晶体进行了热分析,发现在MIT晶体中有Hg溢出现象.     

Bulk Bridgman growth of cadmium mercury telluride for IR applications

Cadmium mercury telluride (CMT, CD_xHg_1-xTe) is the pre-eminent infrared material, despite the difficulties associated with the production and subsequent processing of this ternary compound. By varying the x value the material can be made to cover all the important infrared (IR) ranges of interest. The first technique developed was the basic vertical Bridgman process with typical crystal dimensions of 13 mm diameter and 150 mm length. We found it necessary to purify both the mercury and the tellurium on-site before use to obtain the required electrical properties. There is marked segregation of the matrix elements in Bridgman growth that is both a disadvantage and an advantage. Its disadvantage is that the yield of material in terms of composition for the two most common regions required (x=0.21 and 0.3 for 8–14 and 3–5 m atmospheric transmission windows, respectively) is low. The advantage is that both regions of interest are produced in the same crystal. A further advantage is that segregation of impurities also occurs and leads to low background donor levels in Bridgman material. This Bridgman material is used exclusively for photoconductive IR detectors that require n-type material. The main disadvantages of the Bridgman technique are that material is non-uniform in composition in the radial direction, as well as in the growth direction, and there are numerous grain and sub-grain boundaries. An improved process was developed at BAE Systems based on the accelerated crucible rotation technique (ACRT). Here, growth ampoules are subjected to periodic acceleration/deceleration in their rotation, rather than constant rotation as in the Bridgman process. The major effect of this is to stir the melt during growth and produce flatter solid/liquid interfaces. This, in turn, improves the radial and axial compositional uniformity of the material, normally by a factor of at least ten-fold. The only drawback is that the material is now p-type as grown and must be annealed in mercury vapor to convert it to n-type. An additional marked advantage of ACRT is that the improved radial compositional uniformity enables larger diameter material to be considered. We are currently growing 20 mm diameter, 200 mm long crystals of 0.5 kg weight with acceptable uniformity of composition and good electrical properties for current photoconductive detector programs. © 2001 Kluwer Academic Publishers