共查询到20条相似文献,搜索用时 78 毫秒
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研究了用气相裂解法制备Si-C-N复合纳米微粉时CH3SiHCl2氨解产物先驱体的合成及形成气溶胶时的行为,结果表明:合成温度对先驱体的摩尔质量有较大的影响,摩尔质量随氨解温度的降低而增大;在温度较高时(10℃)合成的先驱体的摩尔质量小,分子内端基存在较多的NH2基因,在气化时-NH2基团与Si-H交联而使残余物增加;在-10℃时合成的先驱体摩尔质量较大,分子内端基上-NH2基因较少,在气化时残余 相似文献
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研究了n-β(氨乙基)-γ(氨丙基)三乙氧基硅烷(NH2(CH2)2NH(CH2)3Si(OEt)3)与二甲基二乙氧基硅烷(CH3)2Si(OEt)2)共水解,制备含(CH2)3NH(CH2)2NH2功能基的聚硅氧烷配位体,用IR,^1HNMR和元素分析法对水解产物分析证明,NH2(CH2)2NH(CH2)3Si(OEt)3与(CH3)2Si(OEt)2进行了共水解反应,而且水解程度随NH2(CH 相似文献
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纳米Si/C/N复相粉体的制备及其在不同基体中的微波介电特性 总被引:1,自引:1,他引:0
以六甲基二硅胺烷((Me3Si)2NH)(Me:CH3)为原料,用双反应室激光气相合成纳米粉体装置制备了纳米Si/C/N复相粉体.研究了纳米Si/C/N复相粉体在不同基体中8.2~12.4GHz的微波介电特性,纳米粉体介电常数的实部(ε’)和虚部(ε”)随频率增大而减小,介电损耗(tgδ=ε”/ε’)较高·纳米Si/C/N复相粉体中的SiC微晶固溶了大量的N原子,在纳米Si/C/N复相粉体中形成大量的带电缺陷;极化弛豫是吸收电磁波的主要原因. 相似文献
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化学气相淀积制备Si3N4超细粉末 总被引:3,自引:0,他引:3
本文研究了SiCl4-NH3-N2-H2系统平衡热力学,确定了Si3N4合成的最佳热力学条件。采用电阻炉化学气相淀积法制备了Si3N4超细粉末,并考察了工艺条件对颗粒形貌的影响。 相似文献
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SiO2—C—N2系统中气相对相稳定的影响 总被引:2,自引:0,他引:2
研究了SiO2-C-N2系统中一定N2分压下,温度与O2、SiO、CO气体分压对相稳定性的影响,绘制了平衡状态下的相稳定性关系图,并以此指导碳热还原氮化法合成高纯Si3N4粉的工艺制备条件。 相似文献
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树脂热解炭制备SiC纳米微粉 总被引:2,自引:0,他引:2
用自制的酚醛树脂热解炭作炭源,用SiO2纳米微粉作硅源,根据碳热还原原理,利用常规加热和微波加热两种方式,分别制备了SiC纳米微粉,X射线衍射,分析电镜检测结果表明:制备工艺和条件对SiC纳米微粉的性质有较大的影响。 相似文献
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Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state. 相似文献
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I. R. Shein S. L. Skornyakov V. I. Anisimov A. L. Ivanovskii 《Journal of Superconductivity and Novel Magnetism》2014,27(1):155-161
The first-principles calculations were performed to predict the elastic and electronic properties of the superconducting ThCr2Si2-type phases CaPd2As2 and SrPd2As2 in comparison with the non-superconducting CeMg2Si2-type phase BaPd2As2. Besides, the same properties were compared for CeMg2Si2- and ThCr2Si2-type polymorphs of BaPd2As2. We found that all these phases are mechanically stable and belong to soft materials with low hardness. The near-Fermi region is formed by the valence states of the blocks [Pd2As2] with decisive contributions of Pd 4d states. The values of N(E F) increase in the sequence: CaPd2As2 < SrPd2As2 < BaPd2As2, i.e. in the reverse sequence relative to the transition temperatures T C. Thus, the change in T C cannot be explained by the electronic factor, i.e. by the simple correlation T C~N(E F). Most likely the decrease in T C in the sequence CaPd2As2 → SrPd2As2 and the absence of a superconducting transition in BaPd2As2 are related to the structural factors and the peculiarities of the electron–phonon coupling mechanism. 相似文献
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We prepared weakly agglomerated powders of ZrO2-CeO2 and HfO2-CeO2 solid solutions 5–8 nm in particle size, consisting of monoclinic and tetragonal phases. After heat treatment at 1200°C, the crystallite size was 30 and 14 nm, respectively. We also examined the effect of precipitate freeze drying on the crystallization of hafnia-based solid solutions containing up to 20 mol % CeO2. 相似文献
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SiO2—TiO2—ZrO2系涂层的制备及其特性 总被引:11,自引:3,他引:8
用溶胶-凝胶法(sol-gel method)在不锈钢表面制备了SiO2-TiO2-ZrO2系无机氧化膜(STZ)。用DTA/TG、IR、XRD和SEM等手段研究了涂层制备时由凝胶向玻璃态的转变以及涂层薄膜的显微结构特点,考察了涂层对基体的保护效果。试验结果表明,在溶胶至凝胶最终转变为无机氧化物的过程中形成了无机网络,Si^4 和Zr^4 充当了网络骨架的形成离子。涂层为无定型玻璃态,其间混有石英、锐钛矿或金红石等微晶。 相似文献
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Thermal diffusion coefficients were measured in two gaseous mixtures, in which one component was close to the critical temperature, in the pressure range (19.6–127.4)·104 N/m2 and at a freon concentration of 0.25–0.8. 相似文献
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High-quality Ag2In2SiSe6 and Ag2In2GeSe6 single crystals have been successfully grown by the vertical Bridgman–Stockbarger method and the horizontal gradient freeze technique, respectively. For pristine and Ar+ ion-irradiated surfaces of the single crystals under study, X-ray photoelectron core-level and valence-band spectra have been measured. Results of these studies allow for concluding that the Ag2In2SiSe6 and Ag2In2GeSe6 single crystal surfaces are sensitive with respect to Ar+ ion-irradiation. In particular, Ar+ ion-bombardment with energy of 3.0 keV during 5 min at an ion current density of 14 μA/cm2 has induced some modification in top surface layers leading to an increase of content of In atoms in the layers. Comparison on a common energy scale of the X-ray emission Se Kβ2 bands representing energy distribution of the Se 4p states and the X-ray photoelectron valence-band spectra reveal that the main contribution of the valence Se p states occur in the upper portion of the valence band, with also their significant contributions in other valence band regions of the Ag2In2SiSe6 and Ag2In2GeSe6 single crystals. In addition, for the single crystals under consideration, temperature dependences of specific dark conductivity and spectral distributions of photoconductivity have been explored. It has been established that the Ag2In2SiSe6 and Ag2In2GeSe6 single crystals are high-resistance semiconductors with value of the specific electrical conductivity σ ≈ 1.67 × 10–9 Ω–1 сm–1 (at Т = 300 K). The both compounds are materials with p-type conductivity. 相似文献
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晶态骨架介孔CeO2和CeO2-ZrO2的合成与结构表征 总被引:1,自引:0,他引:1
以乙酸铈、乙酸锆为无机源,嵌段共聚物P123为模版剂,采用溶胶-凝胶法合成了介孔CeO2及CeO2-ZrO2复合体,用XRD、氮气吸附脱附、TEM、HRTEM、SAED等对材料进行了表征.结果表明,所得介孔CeO2具有规则的晶态孔道结构,孔径约在10nm左右,特别是其孔壁晶粒高度定向排列且平行于孔道方向.原位高温TEM观测表明,该介孔CeO2在800℃仍具有很高的孔道完整性.掺杂ZrO2后发现,在ZrO2摩尔含量低于30%时仍具备高度定向排列结构,高于30%时骨架晶粒取向逐渐趋向无序化. 相似文献