检索结果-南通市图书馆

EFFECTS OF CONVECTIVE FLUID MOTION UPON OXIDE CRYSTAL GROWTH IN HIGH TEMPERATURE SOLUTION

空间科学学报 2002年第Z1期22卷 159-159页

作者： jin weiqing cai lixia liang xinan pan zhilei Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China

　　For understanding of the influence of convective flow on crystal growth, space high temperature in situ observation instrument (SHITISOI) is dedicated to visualize and record the whole growth process of oxide crystals in high temperature up to 1000°C. Model experiments using transparent liquids such as KNbO3 and a mix ture of Li2B4O7+KNbO3 were chosen to investigate effects on ground and in space.On the earth, an investigation of growth kinetics of KNbO3 crystal related to two different states of convection: diffusive-advective flow and diffusive-convective flow,has been performed. The per unit length of a step e is calculated from the exper imental data for two different states of convection. Analyses of these data show the effect of buoyancy convection is to enhance the sharpness of the interface. The growth of KNbO3 crystals from solution of KNbO3+Li2B4O7 was investigated in space. The streamlines of the steady thermocapillary convection in Li2B4O7 solvent was observed. Due to thermocapillary convection, KNbO3 crystal grains grew and filled the whole solution homogeneously. Earth-based quenching experiments are de signed in order to study polyhedral instability of KNbO3 crystal, which is controlled by diffusion mechanism limitation. In all cases, when the crystal was nucleated near air/solution surface, it lost its polyhedral stability and varied from polyhedrons to dedrites. The thickness of diffusion mechanism limitation layer is about 60μm.……

关键词： HIGH TEMPERATURE thermocapillary convection diffusion mechanism high temperature polyhedral instability in situ observation growth kinetics oxide crystals crystal growth the earth in order

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

EVALUATION OF MORPHOLOGY-STABLE CRITICAL SIZE OF KNbO3 CRYSTALS

引用

空间科学学报 2002年第Z1期22卷 163-163页

作者： cai lixia jin weiqing pan zhilei liang xinan Shinichi YODA Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China National Space Development Agency of Japan Ibaraki 305 Japan

　　Skeletal form of KNbO3 crystals growing in Li2B4O7 solvent was in-situ observed at 900°C and it was found that shallow depression started to develop on the surface of KNbO3 crystals when the crystal size exceeded several micron, typically 7 micron.Based on the quantitative criterion derived by Chernov, the estimated critical size of KNbO3 crystals was 1 micron, which was consistent with the experimental measure ment. The kinetic coefficients, kcorner and kcr, in the criterion were experimentally obtained in the diffusive-convective and diffusive-advective flow states respectively.……

关键词： critical size measure ment crystal size form of

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

INTERFACIAL MASS TRANSPORT IN OXIDE CRYSTAL GROWTH

引用

空间科学学报 2002年第Z1期22卷 160-160页

作者： jin weiqing liang xinan cai lixia pan zhilei Katsuo TSUKAMOTO Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Institute of Mineralogy Faculty of Science Tohoko University Sendai 980 Japan

　　A space high temperature in situobservation instrument (SHITISOI) is dedicated to visualize and record the whole growth process of oxide crystal in high temperature melts and solutions. Model experiments using transparent liquids such as KNbO3,Li2B4O7+KNbO3 were chosen to investigate effects of interracial mass transport in oxide crystal growth. For the scaling of the coupled velocity, heat and concentration fields in KNbO3 crystal growth, a rotating crystal growth process was performed and the widths of interfacial concentration, heat and momentum transition zones (The "boundary layers") are obtained, which are 7.5×10-a, 8.6×10-2 and 4.4×10-1 cm,respectively. Hence one can expect that interfacial concentration gradient will be confined to a narrow layer and in region of major concentration change at the in terface. In order to study a mechanism based on the interfacial mass transport resulting from hydrodynamics, the growth of KNbO3 grain in high temperature Li2B4O7 and KNbO3 solutin was studied. The result shows that the pivotal feature in the KNbO3 crystal growth is the initiated by KNbO3 solute surface tension gra dient which is caused by the slow diffusion of KNbO3 solutes. Direct comparison of the model predictions and experimental observed phenomena demonstrate the predictive capability of this model.……

关键词： CRYSTAL GROWTH crystal growth interfacial concentration high temperature mass transport concentration gradient concentration fields surface tension

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

THE CONVECTIVE EFFECT ON THE MORPHOLOGICAL INSTABILITY OF KNbO3 CRYSTALS

引用

空间科学学报 2002年第Z1期22卷 161-161页

作者： cai lixia jin weiqing Shinichi YODA pan zhilei liang xinan LIU Zhaohua Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Space Utilization Research Center Office of Space Utilization System Ibaraki 305 Japan Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China Shanghai Institute of Ceramics The Chinese Academy of Sciences Shanghai 200050 P.R. China

　　Experimentally, it was observed that there were various morphologies of KNbO3 crystals in different regions of the melt of Li2B4O7 and KNbO3 mixture in Pt loop heater. Dendrites grew in the central area of the melt, the diffusive-advective region,in which the temperature gradient is negligible; whereas crystals with smooth sur face were observed in the marginal area, the diffusive-convective region, with large temperature gradient. Based on the solute concentration over the KNbO3 crystal surface examined by electronic probe analysis, it was proved that the combinative effect of buoyancy and surface tension convection induced by temperature gradient enhanced the homogeneity of the solute concentration around KNbO3 crystals and thus their morphological stability.……

关键词： temperature gradient surface tension

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

作者

语言

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：