纳米晶CdFe2O4的制备与湿敏性能研究

采用硬脂酸凝胶法工艺在较低温度下合成Cd-Fe2O4纳米晶材料。TG－DTA热分析表明：纳米晶CdFe2O4在410℃左右晶化形成；XRD、BET比表面吸附等技术表征结果表明，所合成纳米晶CdFe2O4属立方尖晶石结构，平均晶粒度为15－23nm，Cd^2 适度过量对CdFe2O4晶粒生长具有抑制作用。湿敏特性测试结果表明，纳米晶CdFe2O4湿敏元件感湿灵敏度优于相应的常规陶瓷元件，Cd^2 适度过量（Cd^2 /Fe^3 ＞1／2），可达到调制纳米晶湿敏电阻值范围及减小材料湿滞的双重目的。初步探讨了过量Cd^2 影响CdFe2O4纳米晶材料湿敏性能的内在原因。     

In2O3纳米孔材料的制备及其甲醛气敏性能研究

以In(NO3)3·4.5H2O为主要原料,采用溶剂热法成功地制备出In2O3纳米孔材料.采用X射线粉末衍射、透射电子显微镜等对样品的物相和形貌进行了表征和分析,并系统研究了其气敏性能.结果表明,成功合成的六方相In2O3纳米孔材料,其孔径小于17nm,孔道形状复杂且相互连通,以该材料制成的气敏元件对甲醛有很好的气敏性能,对50×10-6甲醛的灵敏度高达23.6.     

ZrO_2－Y_2O_3纳米晶的制备及其湿敏性能

以化学共沉淀法为基础，配合高速剪切均质并添加表面活性剂制备了粒径为２０～４０ｎｍ的ＺｒＯ＿２－Ｙ＿２Ｏ＿３纳米晶，经ＸＲＤ分析为稳定立方相结构。用ＺｒＯ＿２－Ｙ＿２Ｏ＿３纳米晶为感湿材料制作了厚膜型湿敏元件，测试结果表明：（１）元件电阻随相对湿度上升而下降。（２）在总电导中．离子电导占主要成分。（３）元件有较快的感湿响应速度。     

ZrO2—Y2O3纳米晶的制备及其湿敏性能

以化学共沉淀法为基础，配合高速剪切均质并添加表面活性剂制备了粒径为２０￣４０ｎｍ的ＺｒＯ２－Ｙ２Ｏ３纳米晶，经ＸＲＤ分析为稳定立方相结构。用ＺｒＯ２－Ｙ２Ｏ３纳米晶为感湿材料制作了厚膜型湿敏元件，测试结果表明：（１）元件电阻随相对温度上升而下降。（２）在总电导中，离子电导占主要成分。（３）元件有较快的感湿响应速度。     

BaTiO－3纳米晶的湿敏特性研究

本文采用ＳＡＧ法和Ｓｏｌ－Ｇｅｌ法合成了Ｂａ－ＴｉＯ３纳米晶材料，并对其湿敏性质进行了测定。结果表明，ＳＡＧ法合成的ＢａＴｉＯ３纳米晶具有较好的湿敏特性，响应快，恢复时间短，是一个较有前途的湿敏材料     

纳米晶材料的研究及其进展

纳米晶材料是纳米材料研究领域中的热点之一。本文对纳米晶材料的制备方法、表征、结构、性能及其应用进行了综述。     

BaTiO3纳米晶的湿敏特性研究

本文采用ＳＡＧ法和Ｓｏｌ－Ｇｅｌ法合成了ＢａＴｉＯ３纳米晶材料，并对其湿敏性质进行了测定。结果表明，ＳＡＧ法合成的ＢａＴｉＯ３纳米具有较好的湿敏特性，响应快，恢复时间短，是一个较有前途的湿敏材料。     

铁氧化物薄膜气敏材料的制备及性能研究评述

本文综合介绍近年来在铁氧化物薄膜所敏材料制备方法、性能方面的研究新进展，探讨了各种方法的特点。提出了今后铁氧化物气敏传感器的研究及改进方向。     

纳米晶La_(1-x)Sr_xFeO_3薄膜的制备与表征

采用Sol－gel工艺在石英玻璃和硅衬底上成功地制备了纳米晶La1-xSrxFeO3（x=0～0．4）系列薄膜，薄膜为钙钛矿结构，平均粒度在30nm左右。XPS结果表明，随着Sr含量的增大薄膜表面吸附氧含量增大。     

Synthesis of nanocrystalline alloys and intermetallics by mechanical alloying

Nanocrystalline Al₃Ni, NiAl and Ni₃Al phases in Ni-Al system and theα, β, γ, ɛ and deformation induced martensite in Cu-Zn system have been synthesized by mechanical alloying (MA) of elemental blends in a planetary mill. Al₃Ni and NiAl were always ordered, while Ni₃Al was disordered in the milled condition. MA results in large extension of the NiAl and Ni₃Al phase fields, particularly towards Al-rich compositions. Al₃Ni, a line compound under equilibrium conditions, could be synthesized at nonstoichiometric compositions as well by MA. The phases obtained after prolonged milling (30 h) appear to be insensitive to the starting material for any given composition > 25 at.% Ni. The crystallite size was finest (∼ 6 nm) when NiAl and Ni₃Al phases coexisted after prolonged milling. In contrast, in all Cu-Zn blends containing 15 to 85 at.% Zn, the Zn-rich phases were first to form, and the final crystallite sizes were coarser (15–80 nm). Two different modes of alloying have been identified. In case of NiAl and Al₃Ni, where the ball milled product is ordered, as well as, the heat of formation (ΔH _f) is large (> 120 kJ/mol), a rapid discontinuous mode of alloying accompanied with an additive increase in crystallite size is detected. In all other cases, irrespective of the magnitude of ΔH _f, a gradual diffusive mode of intermixing during milling seems to be the underlying mechanism of alloying.     

ZnxFe3-xO4的制备及磁性能研究

采用共沉淀法制备ZnxFe3-xO4铁氧体前驱体，前驱体经高温煅烧即可得到纳米ZnxFe3-xO4铁氧体粉未．利用XRD、SEM和VsM等对ZnxFe3-xO4铁氧体的结构和磁性能进行了研究．实验结果表明，采用本实验方法制备的ZnFe2O4铁氧体颗粒均匀，粒径大约100nm左右，并且颗粒之间团聚成规则的纺锤形结构；不同锌含量对铁氧体的结构和磁性能均有影响．     

Structure and properties of nanocrystalline materials

The present article reviews the current status of research and development on the structure and properties of nanocrystalline materials. Nanocrystalline materials are polycrystalline materials with grain sizes of up to about 100 nm. Because of the extremely small dimensions, a large fraction of the atoms in these materials is located at the grain boundaries, and this confers special attributes. Nanocrystalline materials can be prepared by inert gas-condensation, mechanical alloying, plasma deposition, spray conversion processing, and many other methods. These have been briefly reviewed. A clear picture of the structure of nanocrystalline materials is emerging only now. Whereas the earlier studies reasoned out that the structure of grain boundaries in nanocrystalline materials was quite different from that in coarse-grained materials, recent studies using spectroscopy, high-resolution electron microscopy, and computer simulation techniques showed unambiguously that the structure of the grain boundaries is the same in both nanocrystalline and coarse-grained materials. A critical analysis of this aspect and grain growth is presented. The properties of nanocrystalline materials are very often superior to those of conventional polycrystalline coarse-grained materials. Nanocrystalline materials exhibit increased strength/hardness, enhanced diffusivity, improved ductility/toughness, reduced density, reduced elastic modulus, higher electrical resistivity, increased specific heat, higher thermal expansion coefficient, lower thermal conductivity, and superior soft magnetic properties in comparison to conventional coarse-grained materials. Recent results on these properties, with special emphasis on mechanical properties, have been discussed. New concepts of nanocomposites and nanoglasses are also being investigated with special emphasis on ceramic composites to increase their strength and toughness. Even though no components made of nanocrystalline materials are in use in any application now, there appears to be a great potential for applications in the near future. The extensive investigations in recent years on structure-property correlations in nanocrystalline materials have begun to unravel the complexities of these materials, and paved the way for successful exploitation of the alloy design principles to synthesize better materials than hitherto available.     

纳米晶钛酸铅的合成及其介电性能的研究

采用硬脂酸凝胶法(SAG)制各了纳米晶PbTiO3，用差热—热重分析、红外光谱分析、X光衍射分析及透射电镜等手段对产物的形成过程、晶型、粒径进行了表征。通过对材料介电性能的研究发现，纳米晶钛酸铅在接近静态条件下的低频介电常数远大于常规材料的介电常数，随着粒径的减小，纳米晶钛酸铅的低频介电常数逐渐增大。     

蓝光材料双亲共聚芴的合成、表征与性能

通过Suzuki缩聚方法,将单体2,7-二溴-9,9'-二-(3,6-二氧烷基)芴和9,9'-二辛基芴-2,7-二-(三亚甲基硼酸酯)合成了一种新型的蓝光材料-双亲芴基共聚物.采用1H NMR、13C NMR和元素分析对共聚芴结构进行了表征;通过GPC、DSC和TGA测试,共聚芴有较高的分子量和较窄的分子量分布,同时还有很好的热稳定性.对共聚芴的紫外吸收光谱分析表明,在甲苯溶液和薄膜中的波长分别为389nm和393nm;对共聚芴的荧光发射光谱分析表明,在甲苯溶液和薄膜中的波长分别为415nm和437nm.     

Synthesis, characteristics and oxygen-sensitive properties of SrMgxTi 1 − xO3 nanocrystals

SrMg_xTi_{1 - x}O₃ nanocrystals (x = 0.1–0.6) were synthesized by the stearic acid gel method. Powder samples were characterized by X-ray diffraction and X-ray photoelectron (XP) spectroscopy. The results showed that the lattice parameter a and the O 1s XP spectrum changed not only with the Mg content x but also with the grain size d of the samples. The conductivity of a thick film specimen fabricated on an aluminium oxide wafer was investigated in a nitrogen—oxygen atmosphere.     

无Co混合导电型陶瓷透氧膜的制备和性质研究

首次合成了Ｓｒ１０－ｎ／２ＢｉｎＦｅ２０Ｏｍ（ｎ＝２，４，６，８，１０等）系列氧化物透氧膜，它们具有较高的透氧能力，其中，样品ｎ＝１０在１１００Ｋ时的透氧率为０．９０ｍｌ（ＳＴＤ）／（ｃｍ２·ｍｉｎ），比Ｓｒ１－ｘＢｉｘＦｅＯ３高约两倍．Ｓｒ１－ｘＢｉｘＦｅＯ３（ｘ＝０．１，０．３，０．５）系列的透氧率随Ｂｉ含量增加而增大．通过两个系列氧化物的ＸＲＤ和化学组成的对比，发现Ｂｉ离子含量和晶格空位浓度对透氧能力大小起决定性作用．     

Synthesis and properties of nanocrystalline CsI

The structure and properties of fine CsI powders prepared by spray pyrolysis and synthetic opal (SiO₂) based composites containing CsI in their pores have been studied by electron microscopy, X-ray diffraction, and luminescence spectrometry. The powders consisted of nanocrystalline particles which increased in size from 35 to 55 nm with increasing pyrolysis temperature. In the opal/CsI composites, the CsI nanocrystallites were about 45–50 nm in size and formed a single three-dimensional network between the SiO₂ spheres. In going from bulk crystals to their nanocrystalline analogs, the size effect on CsI luminescence leads to a reduction in luminescence yield, a redshift of the emission bands of the on-center and off-center self-trapped excitons (STEs), and an increase in the contribution of the off-center STEs to the net intrinsic emission yield. The emission decay kinetics of the off-center STEs is insensitive to the crystallite size.     

铈、镧掺杂BaTiO3 基纳米晶的合成与表征

以非全醇盐为原料并避开传统的醇类有机溶剂,利用溶胶－凝胶法以醋酸为介质兼作均相催化剂,按不同配比及工艺条件合成了分别掺杂铈或镧的ＢａＴｉＯ３基纳米晶。利用ＤＴＡ－ＴＧ、ＸＲＤ、ＦＴ－ＩＲ、ＸＲＦ、ＳＥＭ以及陶瓷元件气湿敏特性等测试对纳米晶进行了表征,确定了制备浓溶胶前驱体的优化工艺、酸度、温度、浓度配比、次序、干燥方式等;测定了多晶粉体的原始晶粒粒度、纯度、晶相、软团聚颗粒外观形貌、粒度分布等。     

Synthesis of nanocrystalline CeAlO3 by solution-combustion route

CeAlO₃ was synthesised by a modified solution-combustion route using a mixture of urea and glycine as fuel. A trivalent oxidation state of cerium was stabilised and high-quality single phase polycrystalline CeAlO₃ was obtained by optimising the ratio of fuels. The transmission electron micrography and powder X-ray diffraction investigations showed that the particles were nanocrystalline in nature. Rietveld refinement confirmed the space group of the structure to be I4/mcm$I4/mcm$ with lattice parameters a=5.3278(1)$a=5.3278(1)$ Å, c=7.5717(3)$c=7.5717(3)$ Å. Magnetisation measurements indicated that the sample was paramagnetic up to 2 K. The susceptibility data fitted the Curie–Weiss model in the temperature range 100–300 K with _θp=−40${\theta }_p=-40$ K. The value of _μeff=2.2_μB${\mu }_{\text{eff}}=2.2{\mu }_B$ was close to that expected for a Ce³⁺ ion. The magnetic properties were comparable to that reported for single crystals indicating the high quality of CeAlO₃ prepared in the present work. The semiconducting band gap as estimated from UV–visible spectroscopy was 3.26 eV.