New Ternary Phases in Some Alkaline-Earth Rare-Earth Sulfide Systems

New ternary alkaline-earth rare-earth sulfide phases of composition MLn₂S₇ where M = Ca or Sr and Ln = La, Nd, or Gd have been formed by open-system reactions in flowing H₂S. The phases have been characterized by X-ray powder diffraction and electron microprobe analysis. These compounds form as low-melting ( T _m approximately 1100°C) products when refractory compounds along the MS-Ln₂S₃ join are oxidized at high sulfur fugacities.     

Alkali Tungstates: Stability Relations in the Systems A2O WO3-WO3

Phase relations in the systems alkali monotungstate-tungsten trioxide were investigated in the range 600° to 1100°C.In the Li system, compounds with an A₂O/WO³ ratio of 1:2 and 1:4 are stable and melt incongruently at 745° and 805°C, respectively. In the Na system, the 1:2 compound melts congruently at 746°C, whereas the other 2 sodium tungstates (1:4 and 1:6) melt incongruently at 835° and 913°C, respectively. The K system includes compounds of 1:2, 1:3, 1:4, and 1:6 which melt incongruently at 684°, 842°, 912°, and 964°C, respectively. Eutectic points between the 1:l and 1:2 compounds in these respective systems are at 692°C and 56 mol%WO³, 622°C and 56.3 mol% WO³, and 633°C and 63 mol%WO³. In the Rb and Cs systems, the 1:2 and 1:3 compounds form complete solid-solution series, and their melting temperatures increase with increasing WO³ content, respectively, from 690° to 868°C and from 732° to 902°C. The 1:6 compounds are also stable in these systems and melt incongruently at 1040° and 1046°C, respectively.     

含辛烯醛体系的液液、汽液相平衡研究

测定了水-辛烯醛、水-正丁醇二元系在常压下的液液平衡数据及26.66kPa下的正丁醇-辛烯醛二元系和水-正丁醇-辛烯醛三元系的汽液平衡数据.由测定的3对二元数据求取了NRTL常数及有规参数,并与三元数据进行拟合,计算值与实验值符台良好,液液平衡与汽液平衡得到了统一的关联.     

Ti-N-C-O系的热力学分析与相平衡

本文从热力学的角度分析了TiO2碳热还原反应制备TiC、TiN在不同的PCO、PN2下的最佳温度范围,并绘制了各相稳定存在与PCO、PN2的关系图.     

Lead-Ion Stability in Vitreous Systems

A new glaze composition was characterized and compared with one studied previously in order to evaluate structural model relating lead-ion stability and coloring-ion content to the vitreous system in which they are found. This model is based on the geometrical arrangement of the ionic network, depending in turn on the preferred coordination of the cations involved. The stability of the ionic structure, as indicated by release of Pb²⁺ on acid attack, is correlated with the coordination of sites occupied by network modifiers, i.e. cations producing cubic coordination were associated with increased Pb²⁺ release, whereas the opposite ccurred with those producing anti prismatic coordination.     

Equilibrium Phase Diagrams in the Systems PbO–Ag and CuO–Ag

Silver has played a critical role in the fabrication of metal/ high-T_c superconductor composites. Phase equilibrium in the binary PbO–Ag and CuO–Ag systems has been investigated using differential thermal analysis (DTA), thermogravimetry (TG), and X-ray diffractometry (XRD) techniques. Composition versus temperature diagrams have been established for these systems in air. Eutectic reactions CuO + Ag = L at a composition of Ag = 98.6 mol% and 932°± 3°C for the CuO–Ag system and PbO + Ag = L at a composition of Ag = 8.3 mol% and 825°± 3°C for the PbO–Ag system have been detected. The CuO–Ag system has two immiscible liquid phases in the composition regime of Ag = 30.6–98 mol%, and there are two immiscible liquid phases at the composition range of Ag = 11.7–95.7 mol% in the PbO–Ag system.     

复杂反应体系的化学平衡分析

本文提出了一种新的通用化学平衡计算方法.该方法以反应程度和组分摩尔数同为迭代变量,用松弛法估计初值,Newton-Raphson法加速收敛,具有良好的收敛稳定性.同时用新算法分析了甲烷蒸汽转化中的结焦和Ti(C.N)的化学气相沉积,并对NH_3-CO_2-SO_2-H_2S-H_2O-CH_4-C_2H_6体系进行了热力学计算.所有考证的实例从零初值都得到了正确的结果.     

Nitrogen Dissolution in Sodium Alkaline-Earth Metaphosphate Melts

Phosphorus oxynitride glasses were prepared by remelting (5O – X )Na₂O · X BaO · 50P₂O₅, X = 0, 10, 20, 25, and 30, and 30Na₂O · 20MO · 50P₂O₅, M = Mg, Ca, Sr, and Ba', glasses in anhydrous ammonia. The nitrogen content depends upon the temperature and time of remelting in ammonia and the concentration and size of the alkaline-earth ion. Nitriding the starting glass decreased the dissolution rate in deionized water and thermal expansion coefficient and increased the dilatometric softening temperature and refractive index. The dissolution rate of the base glass in deionized water depended upon the concentration and size of the alkaline-earth ion, but for nitrided glasses, it was essentially independent of the alkaline-earth cation. The thermal expansion coefficient for all the oxynitride glasses decreased with increasing alkaline-earth concentration and cation field strength.     

Property Variation in Alkali Alkaline-Earth Metaphosphate Glasses

Coefficients of helium migration, coefficients of thermal expansion, and glass-transition temperatures were measured for several series of alkali alkaline-earth phosphate glasses. The helium permeability decreases with the field strength of alkali or alkaline-earth ions in the order Na⁺ > Li⁺ and Mg²⁺ > Ca²⁺ > Ba2+. The glass-transition temperature increases and coefficient of thermal expansion decreases with increasing field strength of alkali or alkaline-earth ions. The relationship of lower molar volume, corresponding to decreased coefficients of helium diffusivity reported for other glass-forming systems, occurs in the phosphate glasses.     

甲苯-正庚烷-环丁砜、环丁砜-正庚烷-水——三元体系液液平衡数据的测定与热力学关联

本文测定了甲苯-正庚烷-环丁砜三元体系在30℃和50℃下的液液分层曲线和结线数据,采用了以液液分层曲线和体系物性相结合的分析方法,获得了可靠的数据.本文还测定了环丁砜—正庚烷-水三元体系在50℃下的液液分层曲线,作出了结线.对前一休系的数据进行了热力学关联,求出30℃及50℃时UNIQUAC方程参数.对两个体系均用UNIFAC方法进行预测.计算所得结果相当满意.     

超临界二氧化碳和脂质体系相平衡计算

对超临界CO2和一些脂质体系相平衡计算问题进行了研究.应用Peng-Robinson状态方程及Panagiotopoulos和Reid混合规则,改进能量参数a(T)后,用于计算脂质和超临界CO2组成的二元和三元体系的相平衡,结果与实验数据拟合精度较好.对于一些复杂的混合物如大豆油脱臭馏出物与超临界CO2体系,简化成拟三元、四元等体系进行了计算,计算结果达到一定的精度.     

易挥发弱电解质水溶液的平衡计算

本文用离子质量恒算方程代替电中性方程,将作者开发的多相化学平衡计算方法(KZ算法)推广到易挥发弱电解质水溶液,并将复杂离解反应体系分解为两个简单体系,提出了这类系统平衡计算的一种通用方法.与Sanderson-Chien算法和Gautam-Seider算法相比,本算法具有更好的性能.计算和实验结果吻合良好.     

High-Temperature Energy Relations in Borates: Alkaline-Earth and Lead Borate Compounds and Their Glasses

The high-temperature energy relations in some alkaline-earth and lead borate glasses and compounds of the same compositions are reported. The data obtained with a continuous high-temperature calorimeter and by solution calorimetry in 2 N nitric acid were combined to give heat content versus temperature curves from 25° to 1100°C. The heats of fusion, entropies of fusion, entropy changes vs. temperature, and the free-energy changes from crystal to glass at 25°C are given. Previously unavailable X-ray diffraction data for strontium diborate and calcium diborate are reported.     

Morphology and Stability of the Glass Phase in Glass Ceramic Systems

An explanation is given for the apparent stability of a minor phase in a two-phase system, such as a glass in a glass ceramic, even though normally the glass would be expected to dissolve completely into the crystalline phase. It is shown that the glass would be stable only if it is segregated to the triple-junction nodes and only if the dihedral angle is <π/3. The size and morphology of the glass pocket are obtained in terms of the interface energies, the undercooling below the solidus temperature, and the dihedral angle.     

水-异丙醚-苯酚和水-异丁醇-苯酚体系的液液平衡研究

水-异丙醚-苯酚体系的研究在工业上和环境保护上具有重要意义,但至今未见到液液平衡(LLE)数据的报导今报导了这一系统在两个工作温度的LLE数据.为了寻找萃取剂异丙醚的替代物,我们同时进行了水-异丁醇-苯酚体系的液液平衡研究. 在常压下使用GC-14B气相色谱仪,测定了319 K和329 K时水-异丙醚-苯酚体系的液液平衡(LLE)数据以及水-异丁醇-苯酚体系在319 K和333 K时的LLE数据.用内标法测定了这些体系中除水以外的各组分浓度.在水-异丙醚-苯酚体系中,异丙醚测量的根均方误差为1.4%;苯酚测量的根均方误差为4.6%.在水-异丁醇-苯酚体系中,异丁醇测量的根均方误差为3.1%:苯酚测量的根均方误差为4.6%. 文中给出了上述四个等温截面的LLE数据,同时也给出了相应示意图.2003年我们用工作曲线法(外标法)给出了水-异丙醚-苯酚在319K的等温截面图.两者比较,总体上是类似的,但内标法结果更可靠.这次的研究,还纠正了当时的一个错误估计.对于水-异丁醇-苯酚体系的液液平衡研究表明,异丁醇也是从废水中萃取苯酚的良好萃取剂.但是异丁醇的再生及其循环利用并不如异丙醚那样容易.     

Metathetic Reaction in Reverse Micelles: Synthesis of Nanostructured Alkaline-Earth Metal Phosphates

For the past few years, hydroxyapatite (HAp) has been identified as a potential biomaterial due to its excellent biocompatibility and bioactivity. The preparation of nanostructured HAp with controlled powder characteristics is a pre-requisite for processing it into useful biocomposites. Here, the synthesis of nanorods of calcium hydroxyapatite (Ca-HAp), strontium hydroxyapatite (Sr-HAp), and barium hydroxyapatite (Ba-HAp) by exploiting the metathetic reaction taking place in reverse micelles in the presence of cetyltrimethylammonium bromide has been reported. Powder X-ray diffraction analysis and thermogravimetric measurements confirm the formation of monophasic Ca-HAp and Sr-HAp. The growth of nanorods was further confirmed using transmission electron microscopy studies. The average lengths of Ca-HAp and Sr-HAp were ∼60 and 30 nm, respectively. However, the preparation of Ba-HAp invariably yielded a multiphasic mixture with other competitive phases like BaHPO₄ and Ba(H₂PO₄)₂.     

Prediction of the Equilibrium Composition for High-Temperature Reaction Products in Complex Oxide Systems

Thermodynamic analysis of parallel-serial reaction in complex oxide systems is carried out. The use of the Karapet'yants method to supplement the refined Hooke-Jeeves method has made it possible to determine the optimum range of compositions studied and the most rational temperature interval for heat treatment of coatings. This makes it possible to substantially decrease subsequent experimental search and reduce it to a verification of the optimum interval that is thermodynamically identified.     

用ThermalCal软件辅助化工热力学教学——同时涉及反应平衡与相平衡系统的计算

同时涉及反应平衡与相平衡的综合性反应平衡计算是化工生产过程中经常遇到的问题,亦是化工热力学课程中的重要内容,但其涉及原理多、计算过程复杂,是教学中的一大难题。文中以乙醇脱水生产乙烯的反应为例,提出在合理的假设前提下,用ThermalCal软件辅助计算,能在减少计算工作量的同时得到更接近真实系统的结果。使用ThermalCal软件辅助计算有助于提高学生的计算效率,加深其对反应平衡与相平衡计算原理的理解,从而有效改善课堂教学效果。     

Infrared Spectroscopy of Lead and Alkaline-Earth Aluminosilicate Glasses

Infrared spectroscopic studies of lead and alkaline-earth aluminosilicate glasses in the series x MO- x Al₂O₃ (1 - 2 x )SiO₂ M = Mg, Ca, Sr, Ba, and Pb; 0.05 x 0.275] were carried out in the range 2000 to 200 cm⁻¹. Three major absorption bands were observed in the 1100-, 800-, and 500-cm⁻¹ regions. The frequency and the intensity of the 1100-cm⁻¹ band varied linearly with composition. For a specific value of x , the changes in the frequency, intensity, and bandwidth of this band decreased in the order Mg > Ca > Sr > Pb > Ba and the apparent disorder in the glass structure, effected by the substitution of aluminum, increased in the direction Mg < Ca < Sr < Ba, with Pb in between Mg and Ca. The force constants and the bond orders of the Si-O and Al-O stretching vibrations in each of the glasses increased monotonically as Al/(Al + Si) decreased.     

非缓冲体系中性氨基酸的离子交换平衡

研究了非缓冲体系中性氨基酸在７３２型强酸性阳离子交换树脂上的离子交换平衡，并提出了平衡模型。该理论模型考虑了氨基酸的两性弱解离性质和树脂能团的能量非均一性，可以很好地关联氨基酸与Ｈ＾＋的二元离子交换平衡，并且通过两个二元体系ＶＡＬ／Ｈ＾＋和Ｎａ＾＋／Ｈ＾＋的平衡参数成功地预测了三元体系ＶＡＬ／Ｎａ＾＋／Ｈ＾＋的平衡关系，表明该模型可以描述非缓冲体系中性氨基酸的多元离子交换平衡。