林鸿
,
段远源
工程热物理学报
利用密度平移的方法对Peng-Robinson状态方程计算的液相密度进行了修正,给出了其描述平移量的关联式.对22种卤代烃纯物质的计算结果表明,修正后的PR方程能够很好地计算液相密度,并且能很好地再现纯物质的临界压缩因子,计算精度可以满足工程应用的需要.
关键词:
PR状态方程
,
密度漂移
,
卤代烃
,
临界压缩因子
Physical Review B
In order to understand the unusually large value of zero-field splitting D for the axial Fe3+ center in a KTaO3 crystal, Zhou made two assumptions in his recent report [Phys. Rev. B 42, 917 (1990)]. In this Comment we will show that his assumption II is qualitatively reasonable, whereas assumption I is unnecessary and doubtful.
关键词:
electric-field;srcl2
Journal of Physics and Chemistry of Solids
The layered ternary ceramics Ti3SiC2 and Ti3AlC2 are isostructural and can form Ti3Si1-xAlxC2 solid solutions combining the advanced properties of both compounds [H.B. Zhang, Y.C. Zhou, Y.W. Bao, M.S. Li, Improving the oxidation resistance of Ti3SiC2 by forming a Ti3Si0.90Al0.1C2 solid solution, Acta Mater. 52 (2004) 3631-3637; E.D. Wu, J.Y. Wang, H.B. Zhang, Y.C. Zhou, K. Sun, Y.J. Xue, Neutron diffraction studies of Ti3Si0.9Al0.1C2 compound, Mater. Lett. 59 (2005) 2715-2719; J.Y. Wang, Y.C. Zhou, First-principles study of equilibrium properties and electronic structure of Ti3Si0.75Al0.25C2 solid solution, J. Phys.: Condens. Matter 15 (2003) 5959-5968; Y.C. Zhou, J.X. Chen, J.Y. Wang, Strengthening of Ti3AlC2 by incorporation of Si to form Ti3Al1-xSixC2 solid solutions, Acta. Mater. 54 (2006) 1317-1322]. In the present work, the solid solutions of Ti3Si1-xAlxC2 (x = 0, 0.25, 0.33, 0.5, 0.67, 0.75, 1) are investigated by first-principle calculations based on pseudo-potential plan-wave method within the density functional theory framework. The results show that as Al content increases in the solid solution, all the bonds have weakened to certain extents, which lead to an unstable structure both energetically and geometrically. The calculated results are compared and discussed with the reported data for the Ti3Si1-xAlxC2 solid solutions. (c) 2007 Elsevier Ltd. All rights reserved.
关键词:
ceramics;ab initio calculations;electronic structure;electrical;conductivity;oxidation behavior;mechanical-properties;ti3sic2;temperature;ti3alc2;air;si
林鸿
,
段远源
工程热物理学报
利用比容平移修正后的Peng-Robinson状态方程和密度梯度理论建立了简单流体和烷烃的表面张力的理论模型,并提出了适合于这一类纯物质的作用因子通用关联式.对3种简单流体和21种烷烃的表面张力的计算结果表明,利用新的作用因子关联式结合梯度理论模型能在广泛温度范围内高精度地再现纯物质的表面张力,总的平均绝对偏差为0.19 mN·m-1,计算精度可以满足工程应用的需要.
关键词:
表面张力
,
梯度理论
,
PR状态方程
,
简单流体
,
烷烃
段远源
,
林鸿
,
张庆麟
,
张秋芳
工程热物理学报
目前国际上已商业化使用或提出的潜在的环保工质,大多数为氢氟烃(HFC)混合物,利用状态方程描述混合工质热力性质时,交互作用系数是重要参数之一.本文应用Peng-Robinson状态方程对多种HFC二元混合物的气液相平衡(vapor-liquid equilibrium,VLE)实验数据进行了回归,得到了相应混合物的交互作用系数.提出了交互作用系数新关联式,结果表明所得到的交互作用系数能很好的应用于描述HFC混合物气液相平衡性质,计算精度可以满足工程应用的需要.
关键词:
氢氟烃(HFC)
,
混合物
,
气液相平衡(VLE)
,
二元交互作用系数
,
PR状态方程
ZHOU Jiankun LIU Xianghuai CHEN Youshan WANG Xi ZHENG Zhihong HUANG Wei ZOU Shichang Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai
,
China
金属学报(英文版)
The TiN films were synthesized with an alternate process of depositing titanium from a E-gun evaporation source and 40 keV N~+ bombarding onto the target.It is shown from the composi- tion analysis and structure investigations using RBS,AES,TEM,XPS and X-ray diffraction spectrum that the formed fihns are mainly composed of TiN phase with grain size of 30—40 nm and without preferred orientation,the nitrogen content in the film is much less than that in case without N~+ bombarding,and an intermixed region about 40 nm thick exists between the film and the substrate.The films exhibt high microhardness and low friction. ZHOU Jiankun,Ion Beam Laboratory,Shanghai Institute of Metallurgy,Academia Sinica, Shanghai 200050,China
关键词:
TiN film
,
null
闵琪
,
林鸿
,
段远源
,
宋艺新
工程热物理学报
表面张力是非常重要的物性参数之一,特别对于沸腾和凝结换热的计算是必不可少的.但目前的研究成果主要集中于纯物质,对有重要工程应用前景的混合工质研究还很少.本文应用密度梯度理论,结合比容平移后的Peng-Robinson方程建立了混合物的表面张力模型,该模型不含有任何需要表面张力实验数据回归确定的经验可调系数.计算结果表明,本文建立的模型具有很好的通用性和计算精度,能在广泛的温度范围内较好地再现一般流体混合物和含超临界组元混合物的表面张力数据.
关键词:
表面张力
,
密度梯度理论
,
二元混合物
,
状态方程
闵琪
,
段远源
,
林鸿
,
宋艺新
工程热物理学报
表面张力是重要的物性参数之一,与人们的生产生活密切相关.醇类及其混合物具有重要的工业应用价值.含醇混合物作为特殊的缔合体系,由于氢键的存在,性质复杂.本文应用密度梯度理论结合比容平移后的Peng-Robinson状态方程,回归了醇、水纯净物的作用因子关联式系数,建立了混合物的表面张力预测模型,计算了含醇二元缔合体系的表面张力,该模型不含有任何需要混合物表面张力实验数据回归确定的经验可调参数,对绝大多数含醇混合物具有很好的通用性和计算精度.
关键词:
表面张力
,
密度梯度理论
,
二元混合物
,
醇
,
水
Physical Review B
The assignment of the absorption spectrum of Y3Fe5O12 (YIG) made by Scott et al. [Phys. Rev. B 10, 971 (1974)] is shown to be incorrect and a new one is made by diagonalizing the complete cubic crystal-field matrices for d5 ions, involving spin-orbit interaction, given by Zhou et al. [Phys. Rev. B 44, 7499 (1991)]. The Racah parameters B and C, the crystal-field parameter Dq, and the spin-orbit coupling coefficient zeta are determined (in units of cm-1) as B = 783.3(530), C = 2928(3220), Dq = 1336(1300), zeta = 395 for octahedral Fe3+, and B = 606.1(705), C = 2696(2730), Dq = -1117.3(560), zeta = 335 for tetrahedral Fe3+, where the numerals in parentheses are the values adopted by Scott et al. Furthermore, the cubic zero-field splitting parameter a of Fe3+ in YIG is calculated to be a(oct) = 156 X 10(-4) cm-1 and a(tet) = 58.6 X 10(-4) cm-1. The value for a(oct) differs from the value of 189 X 10(-4) cm-1 found for Fe3+ in Y3Ga5O12:Fe3+. These results support speculations made by Geschwind [Phys. Rev. 121, 363 (1961)].
关键词:
fe3+;mn2+
