Mn掺杂ZnO囊泡结构的制备

通过两步或三步法分别制备两层或三层结构的碳球模板，在溶液中的Zn离子和Mn离子在模板上吸附后再进行煅烧.TEM及SEM显示，煅烧后得到完全复制碳膜板结构的多层Mn掺杂ZnO囊泡.EDS显示Mn在ZnO中的掺杂含量约为1％.样品具有室温铁磁性，饱和磁化率(Ms)及矫顽磁场(Hc)分别为0.032A·m²/kg及0.781kA/m.这种Mn掺杂ZnO纳米囊泡结构使新奇的囊泡结构和ZnO的磁性性能得到了完美的结合.     

预烧对水热BaTiO3介电性能的影响

水热ＢａＴｉＯ３粉料可在１２４０℃进行烧结，但由于粉料含有一定量的表面吸附水和结构水及ＯＨ等缺陷烧结体中气孔较多，介电性能也不理想，粉料在经９００℃，２ｈ的预烧处理后，可去除其中的水及ＯＨ等缺陷，示差扫描量热分析表明，粉料中四方相ＢａＴｉＯ３含量从１５％增加到２８％，并使其烧结体中气孔率降低，介电性能也得到改善。     

水热法制备的BaTiO3微晶粒的特性

本文报道了对水热法制备的ＢａＴｉＯ３纳米微粒性质和缺陷研究的结果．水热法制备的ＢａＴｉＯ３纳米微粒形貌和线度可通过改变前驱物形式和反应条件加以适度调控．在一定的条件下，水热法得到的是在常温下能稳定存在的立方相ＢａＴｉＯ３晶粒．这种“反常”结晶学特性是由于晶粒里含有一定量的Ｏ－Ｈ缺陷和钡离子空位缺陷所造成的．选择适宜的反应条件（如提高反应前驱物钡钛摩尔比等）或采用一定的处理手段（如热处理等），减少或消除这类缺陷，即可消除此“反常”结晶学特性．     

超快大功率SiC光导开关的研究

选用钒掺杂浓度为0.2at%的高质量6H-SiC晶体,电阻率为7.0x108>Ω·cm,研制出超快大功率SiC光导开关.在脉冲宽度为20ns的光源激发下,分别测试了在不同的偏置电压和光能条件下开关的电脉冲输出特性.结果表明:1mm电极间隙的SiC开关器件的性能优越,耐偏压高,光导电脉冲的上升时间快(6.8ns),脉宽<20ns,稳定性好.负载为40Ω的电阻上输出线性电脉冲电压随开关的偏置电压和光强增大而增大,在2.5kV的偏置电压下,最大瞬时电流约为57.5A,瞬时功率高达132kW.     

水热条件下钛酸钡粉体晶粒形成机理

以圩采用加直流电场水热法制备的ＢａＴｉＯ３粉体体系，测定了反应过程中外直流电场电流和反应反溶液中残 ＯＨＪ一。水热反应初期，电流随着反应温度的升高而增大，反应继续进行，电流达到极大值，然后急剧减小。反应温度越高，反应时间越长，反应后溶液里残留的ＯＨ量越少。结合粉体物相和晶粒形貌的表征，对水热条件下ＢａＴｉＯ３晶粒的形成机量进行了探讨。在反应初期，随着温度的升高驱物逐渐溶解，体系中导电离子数不断增多     

An introduction to computational crystallography:the relationship between aluminum-based spinel structures and their morphologies

Computing technology is developing very fast and has permeated among many fields of sci-ence and technology, giving rise to many interdisciplinary subjects. Crystallography, originating from the activity of mining and smelting, has now become a comprehensive subject concerning crystal growth mechanism, chemical composition, structural morphology and physical properties and its research scope is widened by introducing many new achievements from basic sciences such as physics, chemistry, and math…     

Coalescence of the crystallites under hydrothermal conditions (II) —— The morphology and stability energy calculation of cuprite

The coalescence of crystallite under hydrothermal conditions was discussed in our previous paper[1]. When the solute concentration exceeds the supersaturation, the nucleation and growth process take place. The initial crystallites are only several nanometers. They have high surface-to-volume ratio, high index surfaces, and therefore have high surface energy. As the hydrothermal reactions proceed in the alkaline medium, the crystallite surfaces are apt to absorb polar solvate ions such as OH-,…     

Formation mechanism of barium titanate nanocrystalis under hydrothermal conditions

Growth units and the crystallization habit of BaTiO3 nanocrystals have been investigated. It has been proposed that the growth units of BaTiO3 were surface hydroxylated Ti(OH)62- octahedra. The relationship between crystal morphology and the variation of the current intensity in the solution has been obtained through the measurement of the OH in the solution and the hydrothermal experiment with superimposed direct electric field. Based on the computation of the stability energy of the growth units, the relationship between the crystallized morphology of crystallites and the most favorable growth units under different conditions has been derived. It has been found that there is structure similarity between anatase (TiO2) and BaTiO3 from the crystal chemistry viewpoint, so they are soluble in each other, which can serve as a reasonable explanation for the abnormal phenomenon of the retention of cubic substable phase at room temperature.