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Science China(Technological Sciences) 1998年第3期41卷 288-294页

作者：田明原施尔畏王步国元如林李文军仲维卓郭景坤 Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai China Department of Chemistry Jilin University Changchun China Department of Mathematics East-China College of Geology Jiangxi China

The solvothermal preparations of α alumina and boehmite crystallites have been investigated, and the effects of solvothermal conditions such as reactive medium and temperature on the phase, crystallization morphology and size of the crystallites have been discussed. The calculation of the stability energies of the growth units of the crystallites has been performed based on the model of anion coordinate polyhedron’s growth unit. The results could explain the formation mechanisms of the crystallites.

关键词： solvothermal synthesis α alumina and boehmite crystallites morphology stability energies of growth units formation mechanism.

Morphological characteristics of ZnO crystallites under hydrothermal conditions

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Chinese Science Bulletin 1997年第12期42卷 1041-1046页

作者： Wang, BG Shi, EW Zhong, WZ Yin, ZW Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai China

THE ZnO powder （micro-crystallites）, an important functional material, has a wide applica-tion in the fields of ceramics, coatings and electronic devices. However, the powder, usuallyobtained by calcination of zinc oxalate, has a wide particle-size distribution and poor sinteringactivities so various methods for its preparation have been developed. The hydrothermalmethod is widely used to prepare many superfine powders such as ZrO2, BaTiO3, PLZT, dueto many advantages compared with other methods. Recently, the powder of Ⅱ—Ⅵ com-pounds can also be prepared by this method. Furthermore, crystallite shapes may be consid-

关键词： hydrothermal conditions ZnO crystallites crystallization habits.

Morphological characteristics of α-Al_2O_3 crystallites obtained directly from hydro/solvothermal solvents

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Chinese Science Bulletin 1998年第2期43卷 163-166页

作者： WANG Buguo, TIAN Mingyuan, SHI Erwei, ZHONG Weizhuoand GUO Jingkun Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 201800, China Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai China

The morphological characteristics of α_Al-2O-3 crystallites obtained directly from hydro/solv othermal solvents are reported and the formation mechanisms of corundum morphology are discussed from crystal growth and crystal chemistry principles. The crystal growth process is considered as a process of incorporation of growth units on the growth interfaces, and the crystal morphology is determined by the linkage of the coordinated polyhedra.

关键词： hydrothermal crystallization α_Al-2O-3 crystallites morphology growth mechanisms.

ZnCl_2-assisted Synthesis of ZnSe Polycrystal

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Journal of Materials Science & Technology 2012年第4期28卷 373-378页

作者： Changyou Liu Tao Wang Gangqiang Zha Zhi Gu Wanqi Jie State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi'an 710072China

A chemical-assisted element direct-reaction method is developed to synthesize ZnSe compound semiconductor material at a relatively low temperature （-1000 ℃）. ZnSe polycrystal was obtained in the closed-tube systems with Zn-Se, Zn-Se-Zn（NHa）2CI2, ZnoSe-NH4CI and Zn-Se-ZnCI2. The as-synthesized samples were tested by X-ray diffraction （XRD）, thermogravimetric analysis （TGA） and analyzed by thermodynamic numerical method. The results demonstrate that the synthesis efficiency is higher than 99.96% for Zn-Se-ZnCl2 system at around 1000 ℃ for 3 weeks. It also exhibits that not only temperature, but also low apparent ratio of volume and surface area of the source materials and higher ZnCl2 content are required to achieve high synthesis efficiency. A SeCI transporting reaction synthesis process is proposed based on the thermodynamic analysis.

关键词： crystallites Growth from vapor Zinc compounds Semiconducting II-VI materials

Effects of Electric Field on Electronic States in a GaAs/GaAlAs Quantum Dot with Different Confinements

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Chinese Physics Letters 2008年第8期25卷 3021-3024页

作者： A. John Peter Vemuri Lakshminarayana Govt. Arts College Melur-625 106 Madurai India Mohamed Sathak Engineering College Kilakarai-623 806 Rarnnad India

Binding energies of shallow hydrogenic impurity in a GaAs/GaAlAs quantum dot with spherical confinement, parabolic confinement and rectangular confinement are calculated as a function of dot radius in the influence of electric field. The binding energy is calculated following a variational procedure within the effective mass approximation along with the spatial depended dielectric function. A finite confining potential well with depth is determined by the discontinuity of the band gap in the quantum dot and the cladding. It is found that the contribution of spatially dependent screening effects are small for a donor impurity and it is concluded that the rectangulax confinement is better than the parabolic and spherical confinements. These results are compared with the existing literature.

关键词： BINDING-ENERGY IMPURITY STATES HYDROGENIC IMPURITIES MAGNETIC-FIELDS DONOR STATES EXCITON GAAS-GA1-XALXAS crystallites CLUSTERS GAAS

GRAIN　STRUCTURE　CONTROL　OF　NICKEL－BASE　SUPERALLOYS　IN　CASTING　PROCESS：　EFFECT　OF　MELT　ADDITIONS

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Chinese Journal of Aeronautics 1996年第2期9卷 126-129页

作者： Liu Lin Zhang Rong Zheng Jiangbang (Dept. of Applied Physics, Northwestern Polytechnical University, Xi’an, China, 710072)zhen Baolin (Dept. Of Superalloys, Central Iron & Steel Research Institute, Beijing, China, 100081) Dept. of Applied Physics NW Polytechnical University Xi'an 710072 China Dept. of Superalloys Ctrl. Iron and Stl. Res. Institute Beijing 100081 China

Grain structure, dendrite morphologies and shape of MC type carbides ina nickel-base superalloy IN 738 LC are investigated with the addition of carbides,boride, nitride and intermetallic compounds. The results show that the grain size of theingots can be refined extensively to the order of ASTM M11～12 by combination of anintermetallic compound NixAly, addition together with lowering melt homogeneoustreatment temperature during the melting and casting process. In addition, the processcould restrain the formation of script-type carbides. The new process does not changethe phase constitution, freezing characteristics and sub-structure stability. Therefore, itis considered as an effective and practical method of grain refinement for superalloys.

关键词： nickel alloys heat resistant alloys crystallites additives intermetallics

XRD Characterization of Crystallinity of Human Tooth Enamel under Influence of Mechanical Grinding

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Materials Sciences and Applications 2015年第6期6卷 464-472页

作者： Jose Reyes-Gasga Olga Koudriavtseva Raul Herrera-Becerra Arturo Escobosa Instituto de Física UNAM Circuito de la Investigación s/n Ciudad Universitaria México D.F. México Dep. Ingeniería Eléctrica—SEES CINVESTAV—IPN México D.F. México

Crystallinity refers to the degree of structural order in a solid and has a big influence on hardness, density, transparency and diffusion. Even within materials that are crystalline completely, the degree of structural perfection can vary, reflecting size and elastic strain of many independent crystalline regions (grains or crystallites) of which these materials are composed. In this work it was attempted to reduce the crystallinity of human enamel using a technique of mechanical grinding (MG) with an ultra-compact FRITSCH Mini-Mill PULVERISETTE 23 machine. Variation in the crystallinity through the MG was monitored by X-ray diffraction (XRD) by broadening of the diffraction peak and examined using the Williamson-Hall plot method. crystallites in human enamel are regularly arranged and oriented (in the [001] direction) perpendicularly to the interface of enameldentin junction. The results showed an anisotropic feature in crystallinity. Reduction of the crystallinity along the a-axis is due to the crystal strain rather than to the refinement of crystal, and vice versa along the c-axis. After 230 h of the MG, the length of crystallites decreased from 100 nm to 30 nm and width from 40 nm to 37 nm approximately.

关键词： Human Tooth Enamel Crystal Structure Mechanical Grinding X-Ray Diffraction crystallites

The Effect of Interfacial Interactions on a Structure and Properties of Polyurethane Elastomer/Poly(Vinyl Chloride) Blends

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Open Journal of Organic Polymer Materials 2011年第1期1卷 1-7页

作者： T. L. Malysheva S. V. Golovan D. L. Starokadomsky 不详

The effect of chemical structure of segmented poly(urethane-urea)s on its interfacial interactions with poly(vinyl chloride) as well as supramolecular structure and the properties of prepared composites has been studied. A direct influence of flexible and rigid segments of elastomers on a compatibility, structure and the physical-mechanical properties of poly(urethane-urea)/poly(vinyl chloride) blends was investigated. A formation of intermolecular hydrogen bonds network in the poly(urethane-urea)/poly(vinyl chloride) systems was evaluated by FTIR analysis. Morphology studies have shown the effect of interfacial interactions on a size of thermoplastic phase dispersed within elastomer matrix. Obtained poly(urethane-urea)/poly(vinyl chloride) micro- and nanocomposites have improved tensile properties.

关键词： Polymer Composites Compatibility Microphase Separation Glass Transition Hard Domains crystallites Associates H-Bonds Urethane-Urea Groups Interfacial Interactions