Phase stability,microstructure, and dielectric properties of quaternary oxides In12Ti10A2BO42 (A: Ga or Al; B: Mg or Zn)

Quaternary oxides In₁₂Ti₁₀Al₂MgO₄₂ (ITAM), In₁₂Ti₁₀Al₂ZnO₄₂ (ITAZ), In₁₂Ti₁₀Ga₂MgO₄₂ (ITGM), and In₁₂Ti₁₀Ga₂ZnO₄₂ (ITGZ), were synthesized by the solid-state reaction method and the dielectric behavior is reported. The samples were submitted to different sintering temperatures (1473-1773 K) for 24 hours and the phase stability and microstructure were analyzed by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). It is found that the phase decomposition occurs above of 1573 K. Microstructure images showed an increase in the grains size as sintering temperature was raised. The dielectric permittivity as a function of temperature and frequency showed acceptable dielectric constant (15-30) and low dielectric loss (tan δ << 1) values in a wide range of temperature. The band gap obtained by the optical spectrum analysis is about 3.5 eV indicating good dielectric insulating compounds. Furthermore, the electrical conductivity, the activation energy, and the conduction mechanisms are analyzed and discussed in a whole range of temperature. The good dielectric values, ε′ (15-20) and tan δ (~0.004), and their behavior (almost independent of the frequency and temperature) almost constant within a wide range of temperature make these quaternary oxides interesting in electroceramic applications.     

Gibbs-Duhem方程与前传网的集成方法及其在汽液相平衡中的应用

提出了以Gibbs-Duhem方程为基架,引入前传网,由此将机理方程与神经网络这两种不同类的方法相集成,用以求解化工热力学的汽液相平衡问题,以克服经典的机理方法或单一神经元方法的欠缺与不足。将这种集成方法应用于恒温、恒压二元体系,由液相组成确定汽相组成,效果良好。应用实例表明该法计算简便,预测精度高,且稳定性好,显示出胜于两种单一方法的优越性。     

0.4～0.8MPa气压下二元混合气体SF_6/N_2和SF_6/CO_2露点温度计算

金属封闭开关设备(gas insulated switchgear,GIS)和气体绝缘输电线路(gas insulated transmission line,GIL)等高压电力设备多采用提升气压的办法来提高SF6混合气体的绝缘强度,而随着气压的升高,混合气体的露点温度随之上升,在一定条件下,甚至超过了GIS和GIL设备的适用范围。该研究采用Peng-Robinson(PR)状态方程结合van der Waals混合规则(PR-vd W方法)分别对二元混合气体SF6/N2和SF6/CO2的汽液相平衡数据进行了计算,得到在0.4～0.8 MPa气压下,不同配比的SF6混合气体的露点温度。结果显示:对于目前使用的GIS和GIL设备,当气压分别为0.6、0.7和0.8 MPa,建议SF6/N2混合气体运行在SF6气体占混合气体摩尔分数分别0.84、0.74和0.66的情况下,SF6/CO2混合气体运行在SF6气体占混合气体摩尔分数分别0.77、0.60和0.47的情况下。且在GIS和GIL设备中,SF6/N2混合气体的环境适用范围较SF6/CO2混合气体的更广。     

Molecular thermodynamics approach for liquid-liquid equilibria of the symmetric polymer blend systems

We extended and simplified the modified double-lattice model for polymer solution systems to binary polymer blend systems. The model has three model parameters, C_β and C_γ in a primary lattice and C_a in a secondary lattice. Those are not adjustable parameters but universal constants. In comparison with Müller's Monte-Carlo simulation data for symmetric polymer blend (r₁=32 and r₂=32), C_γ is determined and C_β is negligible for symmetric polymer blend systems. Also, C_a is obtained from comparing with Panagiotopolous’ Monte-Carlo simulation data. In addition, oriented interactions between polymer segments are considered based on the secondary lattice concept. The proposed model describes very well phase behaviors of ordinary and oriented polymer blend systems.     

Measurement and modeling of vapor-liquid equilibrium for ternary system water + 2-propanol + 1-butyl-3-methylimidazoliumchloride简

Vapor-liquid equilibrium （VLE） data for water ＋ 2-propanol ＋ 1-butyl-3-methylimidazolium chloride （[bmim]Cl） were measured. Six sets of complete T, x, y data are reported, in which the 2-propanol mole fraction on IL-free basis is fixed separately at 0.1, 0.2, 0.4, 0.6, 0.8, and approximate 0.98, while the IL mass fraction is varied from 0.1 to 0.8, in an interval of 0.1. The non-random-two-liquid （NRTL） and electrolyte non-random-two-liquid （eNRTL） equations are used to correlate the experimental data with satisfactory results. The ternary VLE behavior is also modeled with the parameters obtained by correlating two data sets, in which the mole fraction of 2-propanol on IL-free basis is approximately 0.1 and 0.98. In this way, the six sets of data are reproduced satisfactorily. With the eNRTL model, the root-mean-square deviation for temperature is 0.82 K and that for vapor-phase mole fraction is 0.0078. The influences of IL on activity coefficients and relative volatility of the volatile components are also graphically illustrated.     

加料顺序对两种盐溶解性的影响

盐的溶解及盐效应的研究对化工技术开发具有重要意义。采用平衡法,常压下,测得了对苯二甲酸二钠在不同温度下于水中的溶解度。在常压和298.15 K下,考察了对苯二甲酸二钠等7种有机盐和无水硫酸钠等3种无机盐在水中的两两溶解过程,发现加料顺序会影响两种盐的溶解性。得到如下结果:先溶解难电离的盐再溶解易电离的盐,则后者的溶解速度变化不明显;而先溶解易电离的盐再溶解难电离的盐,则后者的溶解速度会显著降低且溶解度变小。将其中一种盐的量固定后,在一定时间内另一种盐所能溶解的量定义为准溶解度。测定了对苯二甲酸二钠在不同浓度的柠檬酸三钠水溶液中的准溶解度,为相关化工行业的产品分离纯化提供依据。     

Progress and trends in hydrate based desalination (HBD) technology: A review

The shortage of freshwater boosts the development of seawater desalination technology. As a novel method, the hydrate based desalination technology has been put forward for decades and achieved considerable development in the past years. This review focuses on the experimental progress at the aspects of the hydrate former choice, formation promotion and ion removal efficiency and conceptive innovation of hydrate separation and energy utilization. It should be noted that gaseous hydrate former with low formation pressure and insoluble liquid hydrate former are worthy for further study. Besides, the water migration caused by propane deserves to be investigated much more deeply for the potential value of wide application. Moreover, the utilization proposal of LNG cold energy brings more possibility of commercial application. In a word, the hydrate based desalination technology is hopefully an environment friendly, low-cost and widely used desalination technology in the near future.     

莰烯+(+)-3-蒈烯体系汽液平衡数据的测定与关联

改进了Ellis平衡釜的保温、搅拌与压力控制系统，建立了一套可视窗口的实验装置。测定了莰烯+(+)-3-蒈烯体系在313.15、373.15和433.15 K下的汽液平衡数据；采用面积法和Van Ness检验法对实验数据进行热力学一致性检验，所有数据均符合Gibbs-Duhenm的热力学一致性；选用Aspen plus软件中NRTL、Wilson和UNIQUAC模型，由最大似然法对目标函数进行优化，实现对实验数据的关联。结果表明，气相组成和平衡压力的估算值与实验值的最大平均相对偏差为0.0128和0.0009，最大均方根偏差为0.0003和0.0012 kPa，相对挥发度的估算值与实验值的绝对平均偏差分别为0.09%、0.03%和0.04%。