排序方式: 共有8条查询结果,搜索用时 687 毫秒
1
1.
Jing-Xue Wu Guo-Cheng Zhang Bin Zhao Shuo Wang Ji-Lin Cao 《Journal of solution chemistry》2017,46(1):58-69
Based on the requirement for the comprehensive exploitation and utilization of the salt lake resources magnesium chloride and potassium chloride, a new technology to produce KCl and ammonium carnallite (NH4Cl·MgCl2·6H2O) by using NH4Cl as salting-out agent to separate carnallite is proposed. The solubilities of quaternary system KCl–MgCl2–NH4Cl–H2O were measured by the isothermal method at t = 60.00 °C and the corresponding phase diagram was plotted and analyzed. The analysis of this phase diagram shows that there are seven saturation points and eight regions of crystallization. These eight regions of crystallization represent salts corresponding to KCl, NH4Cl, MgCl2·6H2O, (K1?n (NH4) n )Cl, ((NH4) n K1?n )Cl, (K1?n (NH4) n )Cl·MgCl2·6H2O, KCl·MgCl2·6H2O and NH4Cl·MgCl2·6H2O. According to the phase diagram analysis and calculations, ammonium carnallite (NH4Cl·MgCl2·6H2O) and KCl can be obtained using carnallite as raw materials and ammonium chloride as salting-out agent at t = 60.00 °C. The new technology shows the advantages of being easy to operate and having low energy consumption. The research on this quaternary phase diagram is the foundation for reasonable development of carnallite resources and comprehensive utilization of the salt lake brines. 相似文献
2.
More than one hundred models were designed to reflect the local structure and electronic property of Ni-Fe amorphous alloys. After calculating by DFF method, a series of configurations of clusters NixFe and NiFex (x = 1 - 5) were gained. The configurations, which possessed the lowest energies and non-imaginary frequencies, were considered the most stable optimized structures. The catalytic activity, charge and magnetic properties were analyzed and discussed. The different Fe content changed the catalytic properties of clusters through altering the value of Fermi level of every cluster. However the density of state (DOS) nearby Fermi level and average 3d orbital population of atom Ni, which were also important properties related to the catalytic activation, were little changed. Based on the Fermi level, the activity of catalyst toward hydrogenation reaction would be considered best when the ratio of Ni to Fe was close to 1. The Fermi level of clusters was far distant to the level of nitrogen in singlet state. It would be the reason why the reaction condition in ammonia synthesis and nitrogen fixation process was rigorous. When Fe atom contents were higher than 75% (NiFe3), the electrons transferred from atom Fe to Ni, but when the ratio was decreased, the transfer was reversed. The ratio of atoms of local structure also played an important role in the aspect of electron transition. On the average 3d orbital population of atom Fe, the average magnetic moments of Fe atoms in clusters were calculated. When Fe atom contents were 50% nearly, the average magnetic moment achieved the highest point. 相似文献
3.
4.
FANG Zhi-Gang GUO Jing-Xue 《结构化学》2007,26(3):273-280
In the present paper,one hundred cluster models NinBP (n=1~6) have been designed and studied by density functional theory (DFT) to get an insight into the local structure,catalytic properties and sulfur resistibility of amorphous alloy Ni-B-P. The configurations in triplet state are found more stable than those in the singlet state. It is found that as the content of Ni in the clusters increases,the value of Fermi level in clusters fluctuated,which shows that the content of Ni can influence the Fermi level to a certain extent. Based on the Fermi level and DOS,we consider the activity of catalyst in hydrogenation reaction is the best in cluster Ni3BP. On the basis of the charge of clusters NinBP (n=1~6),we conclude the amorphous alloy Ni-B-P with high Ni content has better sulfur resistibility and the best hydrogenation activity,strong sulfur resistibility appears in clusters Ni3BP,and the amorphous alloy Ni60B20P20 with similar proportion is expected to prepare in the future. 相似文献
5.
Critical exponents of ferroelectric transitions in modulated SrTiO3:Consequences of quantum fluctuations and quenched disorder 下载免费PDF全文
The ferroelectric transitions of several SrTiO3-based ferroelectrics are investigated experimentally and theoretically, with special attention to the critical scaling exponents associated with the phase transitions, in order to understand the competition among quantum fluctuations (QFs), quenched disorder, and ferroelectric ordering. Two representative systems with sufficiently strong QFs and quenched disorders in competition with the ferroelectric ordering are investigated. We start from non-stoichiometric SrTiO3(STO) with the Sr/Ti ratio deviating slightly from one, which is believed to maintain strong QFs. Then, we address Ba/Ca co-doped Sr1-x(Ca0.6389Ba0.3611)xTiO3(SCBT) with the averaged Sr-site ionic radius identical to the Sr2+ ionic radius, which is believed to offer remarkable quenched disorder associated with the Sr-site ionic mismatch. The critical exponents associated with polarization P and dielectric susceptibility ε, respectively, as functions of temperature T close to the critical point Tc, are evaluated. It is revealed that both non-stoichiometric SrTiO3 and SCBT exhibit much bigger critical exponents than the Landau mean-field theory predictions. These critical exponents then decrease gradually with increasing doping level or deviation of Sr/Ti ratio from one. A transverse Ising model applicable to the Sr-site doped STO (e.g., Sr1-xCaxTiO3) at low level is used to explain the observed experimental data. It is suggested that the serious deviation of these critical exponents from the Landau theory predictions in these STO-based systems is ascribed to the significant QFs and quenched disorder by partially suppressing the long-range spatial correlation of electric dipoles around the transitions. The present work thus sheds light on our understanding of the critical behaviors of ferroelectric transitions in STO in the presence of quantum fluctuations and quenched disorder, whose effects have been demonstrated to be remarkable. 相似文献
6.
Quantum Chemical Study on Geometry and Property of Cluster Ni_4P 总被引:1,自引:0,他引:1
1INTRODUCTION Amorphous alloys attractive to scientists have worked in the field of materials and catalysts since they have many excellent physical and chemical pro-perties,such as high magnetic susceptibility,high specific heat,high strength,ductile in compression,low coefficient of friction,high corrosion resistance,super plasticity within the range,ferromagnetism and super conductivity[1~5].Especially,amorphous alloys as catalytic materials have shown either hig-her activity or selectiv… 相似文献
7.
8.
1