Ju LUO
,
Xingzhao DING
,
Benpei CHEN and Jie KONG(Institute of Solid State Physics
,
Academia Sinica
,
Hefei
,
230031
,
China)Yuanda DONG(Dept. of Metallurgy and Materials
,
Shanghai University of Technology
,
Shanghai
,
200072
,
China)
材料科学技术（英文）
The development of microstructure of nanometer TiO2 powders prepared by a sol-gel process was systematically studied. Grain growth was mon itored using X-ray diffraction (XRD) and transmission electron microscopy (TEM). and the Debye temperature of anatase crystallites was determined. It was found that the grain size of the powders increased slowly with annealing temperature up to 773 K. but grew rapidly in the temperature range of 773-1273K. The activation energies (Ea) for the growth of anatase crystallites in the two temperature regions were calculated to be 16 and 90 kJ / mol, respectively. The Debye temperatures of nanocrystalline anatase powders were all lower than that of microcrystalline anatase. which implies that the bonding force between Ti and O atoms in nanocrystalline TiO2 shourd be smaller than that in microcrystalline state. However. it was noted that the Debye temperature of nanocrystalline anatase increased with the decrease of grain size. This may be attributed to the enhancement in atomic bonding force due to the existence of high surface tension in nanocrystalline powders
关键词:
杨文虎
,
易冉
,
徐阳
,
惠思思
,
曹晓珑
绝缘材料
doi:10.3969/j.issn.1009-9239.2012.01.014
研究了不同外施工频电压下环氧树脂绝缘中的电树枝结构、生长的特性,并用Ding等提出的模型解释了电树枝的发展过程,模拟了其生长曲线.结果表明:在同一电压下,环氧树脂中电树枝的生长速度基本为恒定值,随外施电压的升高,电树枝分枝变少,生长速度基本呈指数增加,且利用模型模拟的生长曲线与实验测试的结果吻合,最后讨论了模型的物理基础.
关键词:
电树枝
,
环氧树脂
,
劣化
,
动力学
,
模型
,
模拟
陈伟亮
,
张宁
,
唐昭辉
,
丁学勇
材料研究学报
将Miedema模型与实验数据相结合得到适于Miedema模型的O和S的参数(O:电负性7.04、电子密度6.03、摩尔体积4.59;S:电负性5.8、电子密度3.24、摩尔体积6.97),计算了141种O的二元化合物和145种S的二元化合物生成焓其平均绝对误差(MAPE)分别为36.8％、32.4％.结合Ding导出的三元系相互作用系数计算模型,计算了1873 K时Fe基熔体中O和S与其它元素之间的相互作用系数.与实验数据的比较表明,除个别元素外,计算值与实验值之间误差不大且变化趋势比较一致.将误差较大的Nb、Ag、Pt的电负性参数由原来的4.05、4.35、5.65修正为4.31、4.17、5.57,使用Miedema模型的计算精度有很大的提高.
关键词:
材料科学基础学科
,
Miedema模型
,
含O和S熔体与合金
,
相互作用系数
,
参数的修正
