STUDY ON STRUCTURE,CHEMICAL BOND AND THERMOELECTRIC PROPERTY OF BORON CARBIDES

The correlation between structure, chemical bond and thermoelectric properties of boron carbides is discussed based on structural calculations with self-consistent-field discrete variation (SCF-DV-Xa) method, one of calculation methods of molecular orbital in quantum chemistry. Nine different structural models for calculation are proposed. The calculated results show that the chain is negatively charged and the icosahedron is positively charged, i.e. [C-B-B(C)]δ-[B11B(C)]δ. The total strength of the five covalent bonds between an atom and     

GRADIENT VARIATION OF COMPOSITION AND QUANTUM CHEMISTRY CALCULATION OF(Ti-Nb)C-Ni COMPOSITE

(Ti,Nb)C Ni composite is prepared.Theanalyses of SEM,EPMA and TEM/EDAX show that (Ti,Nb)C-Ni consists of three phases,which are called interior,transitional and Ni phases respectively.Several models arecalculated by self-consistent-field variational Xa(SCF-DV-Xa)me thod,one of the quantum chemistry calculatingmethods.The calculated results show that when Ni elementincreases,the bond orders(measures of strength of covalentbonding)of Ti-C and Ni-C in the models decrease corre-spondingly,which is to say that there is a gradient variation of the covalent bond in the transitional phase which is compat-ible with both the interior and Ni phases.It is beneficial for improving the mechanical properties of the materials.     

STUDIES OF QUANTUM CHEMISTRY CALCULA- TION ON VALENCE-BOND STRUCTURE AND HYDRATION ACTIVTY OF C_(12)A_7

The structure,chemical bonds and hydra-tion activity of C_(12)A were studied by SCC-DV-X.methodof computational quantum chemistry.The calculated resultsshow that Ca-O bond will be first broken off when C_(12)Ahydrates,the reactivity of Al(2)O_4 tetrahedron,is superiorto that of Al(1)O_4tet(?)hedron and the rupture of the-Al-O-Al chain composed of two types of AlO_4 tetrahedra un-der the action of water ties in the very weak Al(2)-O(2)bonds.the Al-O bond strength of C_(12)A_7 is between C_3A andC_(11)A_7·CuF_2.     

STUDY ON STRUCTURE AND PROPERTY OF Nb-DOPED TiC CERAMIC WITH QUANTUM CHEMISTRY CALCULATIONS

Nb-doped TiC ceramic,or (Nb_yTi_(1-y)) C_x, inwhich amount of Nb element added is increased from zero to40Wt.%, synthisized with self propagating high temperaturesynthesis, is studicd with SCF-Xa-DV,a quantum chemistry cal-culating method. The chemical bonding is studied to discuss therelation between structrues and properties. Several classes ofmodels in which there is no vacancy,one vacancy or two vacan-cies have been calculated. From the calculated results of bond or-der, a measure of covalent bond strength, and molecule orbitalcontotr map, it is concluded that when Nb element added in-creases, the vacancies increase correspondinigly, the covalent com-ponent of chemical bonds of the samples decreases while the met-al-bonding component increases, so the hardness and resistanceof the samples decrease.     

QUANTUM CHEMISTRY STUDIES ON THE STRENGTH PERFORMANCE OF ETTRINGITE

Ettringite is a main hydrate of cement,and theSr-bearing ettringite is a main hydrate of Sr-bearing calciumsuplhoaluminate.In this paper the two hydrates are studiedby a quantum chemistry method,the self-consistent-field dis-crete variation X_α.method (SCC-DV-X_α).The results show:their bond order of Al and covalent bond order of Al-O bondare alike;that the bond order of Sr and the covalent bond or-der of Sr-O in Sr-bearing ettringite are higher than these ofettringite is the main reason,that the strength of Sr-bearingettringite is higher than that of ettringite.     

STRUCTURES,PROPERTIES AND QUANTUM CHEMISTRY STUDIES OF As-S-X(X=Cl,Br,I)AND As-Y-Br(Y=S,Se,Te)GLASSES

As-S-X(X=Cl,Br,I)and As-Y-Br(Y=S,Se,Te)glasses are studied with Self-Consistent-Field Dis-crete Variational X_α(SCF-DV-X_α),one of the molecule orbital.calculating methods in quantum chemistry.The chemicalbonding is studied to discuss the relations between structuresand properties with the variations of compositions of theglasses.The calculated results show that the strength of cova-lent and ionic bonds are both in the order of As-S-Cl>As-S-Br>As-S-I as well as As-S-Br>As-Se-Br>As-Te-Br,it isconsistent with the experimental result of the glass-transitiontemperature (Tg) of the corresponding glasses.The differ-ences of chemical bond strength and Tg among As-S-X(X=Cl,Br,I)glasses are larger are larger than those among As-Y-Br(Y=S,Se,Te)glasses and the largest difference ofchemical bond strength is that of ionic bond of As-X amongAs-S-X(X=Cl,Br,I)glasses,so the variations of X(X=Cl,Br,I),the end atoms on the chains in the glasses,play themore important role to affect the struture and property of theglasse     

卤代苯酚系列阻燃剂的量子化学研究

对卤代苯酚、卤代间甲苯酚及其二聚物进行了量子化学计算,获得了Mulliken键级、分子轨道和能级。并初步探讨了这些物质的阻燃机理和阻燃效果。     

硼对铬系白口铸铁组织与性能的影响

本文研究了硼对铬系白口铸铁组织中碳化物形貌及其力学性能的影响。结果表明,加入适量的硼后,在亚共晶低铬白口铁中,能使连续网状的莱氏体型共晶碳化物转变为孤立的块状;在亚共晶高铬白口铁中,使共晶碳化物分布均匀;在过共晶高铬白口铁中,可使初生碳化物由粗大的六角形转变为细小、圆整的团状,力学性能亦有较大幅度的提高。测试还表明,硼有使铬系白口铁共晶转变开始温度下降的倾向。     

类胡萝卜素的紫外可见光谱特性及其应用

对类胡萝卜素紫外可见吸收光谱(UV—VIS)的部分特性进行了综述。重点讨论了类胡萝卜素UV—VIS最大吸收峰的位置、形状及影响因素，类胡萝卜素异构化对UV—VIS的影响，与类胡萝卜素UV—VIS有关的化学测试反应在其结构鉴定中的应用。     

量子平面的变形振子实现及其应用

借助量子理论中的Ｂａｒｇｍａｎｎ表示，利用变形谐振子给出了量子平面的一种实现，并讨论了该实现的一些应用。     

物理化学教学评价及对策研究

通过对学生关于分析化学仪器维修专业物理化学教学的评价作调查,得到了一些很有价值的反馈信息。提出了今后物理化学教学中应注意的问题及其对策。     

卤代苯酚系列阻燃剂的量子化学研究——聚合物线性结构的研究

对卤代苯酚和卤代间甲苯酚进行了量子化学计算,获得了原子的自由价和原子的净电荷密度,由实验得到相应聚合物的Ｈ１－ＮＭＲ和Ｃ１３－ＮＭＲ谱图,由此探讨了由单体生成相应聚合物的线性结构情况．     

用差分概念法和偏导数法计算滑动轴承动特性的精度分析

本文对180°无限长圆柱轴承(偏位角θ=90°)的动特性进行了理论分析,推导出各刚度系数、阻尼系数的解析表达式,并用差分概念法和偏导数法求出了各系数的数值解,将其与解析解作了比较,定量地说明了两种数值计算方法的精度以及计算中采用不同的函数形式、扰动量、分格数对精度的影响。     

聚并苯、聚并吡啶和多聚氰结构和电子性质的比较研究

采用量子化学－维紧束缚的ＳＣＦ－ＬＣＡＯ－ＭＯ法，对于聚并苯分子以及它的链中－ＣＨ＝被－Ｎ＝部分取代后得到的聚并吡啶，多聚氰分子进行了理论研究。能带结构分析表明：Ｎ的取代改变了结构的多样性，增多了亲电或亲核掺杂的活性点，但本征导电性能未得到改善。     

造纸配料组分的湿部化学

对造纸配料组分及其胶体化学特性、表面动电行为、配料组分的聚集、吸附等作了较为系统的论述．     

汤姆逊散射之跃迁几率和散射截面的量子场论方法处理

汤姆逊散射为典型的弹性散射,即低能量光子被电子散射的过程.计算汤姆逊散射的跃迁几率和散射截面,量子力学的方法是求解薛定谔方程,并采用十分有效的分波法进行处理.本文运用量子场论方法进行计算,结果正确且方法简捷.     

湖南临澧膨润土矿蒙脱石的矿物化学及成因

在一定Ａｌ的总数浓度范围内，Ａｌ在蒙脱石四面体和八面体层中的分配比例同其本身浓度无关，而与Ｓｉ在四面体－溶液中和Ｆｅ３＋，Ｍｇ，Ｆｅ２＋等在八面体溶液中的比值分别成正比和反比。Ｆｅ３＋进入八面体替代Ａｌ的量明显高于Ｍｇ表明蒙脱石可能在低温条件下形成或原始介质中的Ｆｅ３＋高于Ｍｇ。本区蒙脱石的成因类型属于流纹质火山物质在水的长期作用下形成的富Ｆｅ３＋贫Ｍｇ的Ｗｙｏｍｉｎｇ型     

STUDY ON SOLUTION CHEMISTRY BETWEEN TANNIC ACID AND THE FLOTATION PULP OF WOLLASTONITE AND DIOPSIDE

The mechanisms of interaction betweentannic acid and calcium ions either addedexternally to or inherently present in the volution(dissociated from mineral surface),arestudied by the use of Inductively Coupled PlasmaAtomic Emission Spectroscopy(ICP-AES),Ultraviolet Spectroscopy(UV).It is found thatwollastonite has a high solubility in theconcentration of calcium ions,calcium ions areable to interact with tannic acid.     

氢键对马来酸、富马酸酸度影响的量子化研究

利用ＭＮＤＯ法，计算了马来酸、富马酸酸式离解过程的总能量变化，电荷分布及键合能．从微观角度讨论了分子内氢键的形成对二酸酸性的影响，计算结果与实验结果一致。