石英晶体碱(KOH)腐蚀像及其与酸(HF)腐蚀像对比研究

本文用KOH溶液对石英晶体进行腐蚀实验.对石英晶体不同结晶学方向的5个品面(切面)的腐蚀像进行观察,建立了石英碱腐蚀形貌的立体模型,并与酸(HF)溶液所腐蚀的同样5个面的腐蚀像进行对比.研究发现碱腐蚀与酸腐蚀在柱面{1010}和菱面{1011}、{0111}上有很人不同,在柱切面{1120}、{2110}上有相同之处.但它们都反映各品面及晶体的对称特点.该研究对揭示矿物晶体在不同酸碱地质环境下腐蚀的特点具有指导意义.     

Top-Seeded Solution Growth of Monomethylurea Single Crystals

It was previously reported on the growth of monomethylurea (NMU) single crystals from methanol solution by a mechanical limitation-direction (MLD) technique in which long (100) oriented seeds, capped on their extremities, were employed. The crystals obtained by this technique, in spite of their good structural and optical quality, presented their core region, in which the seed was located, with a higher density of structural defects and henceforth a reduced cross section useful for optical applications. It is here referred to a new, top-seeded growth configuration, devised on the basis of a preliminary PBC analysis for assessing the morphological importance of the crystal faces experimentally observed during crystal growth, which allows to grow NMU crystals in which the defected core region is removed for almost the entire length of the crystal.     

阳离子Gemini表面活性剂溶液的自组装结构

两亲性表面活性剂(Gemini)是通过一个联接基团将两个传统表面活性剂分子在其亲水头基处连接在一起而形成的一类新型表面活性剂.构建了表面活性剂分子球簧结构模型,采用耗散粒子动力学方法(DPD),研究了表面活性剂在水溶液中的自组装行为,考察了添加剂醇分子对表面活性剂自组装结构以及临界胶束浓度(CMC)的影响.结果表明随着表面活性剂分子浓度的增加,其水溶液中依次出现球状、蠕虫状以及层状胶束等自组装结构;添加醇分子可提高表面活性剂疏水基团在溶液中的溶解性从而增大表面活性剂溶液的CMC,具有抑制胶束生成的作用.     

反式二苯乙烯(TSB)的溶液法晶体生长

本文观测了TSB在苯甲醚等有机溶剂中的结晶习性,测定了相应的溶解度曲线和亚稳区.采用溶液降温法在50~30 ℃的温度范围内进行晶体生长,获得透明度好的厘米级TSB晶体.通过对所得晶体进行X射线粉末衍射、紫外-近红外透过光谱、吸收光谱和紫外荧光光谱等测试,表明:本实验使用的不同生长溶剂对TSB晶体结构不会产生影响,所得晶体在410~1000 nm波长范围内透过率不低于80;,而在200~360 nm范围内有吸收,在波长为272.8 nm的激发光作用下,得到较强的荧光峰,峰位为386 nm.     

Growth Kinetics of Potassium-Dihydrogen Phosphate Crystals in Solution

Growth rate data of (101) faces of KDP crystals as a function of the relative supersaturation of the solution are analyzed on the basis of BURTON , CABRERA and FRANK surface-diffusion model applied to the growth from solution. The characteristic constants in the BCF function are determined for 50°C. Approximate values of the free activation energies for dehydration, desorption, surface diffusion and entering the kinks from the surface are calculated. The experimental data previously obtained by MULLIN and AMATAVIVADHANA and by BELOUET are also discussed.     

The Dimer Association of Stearic Acid in Solution

The dissociation constant of stearic acid was determined in four different solvents, using the Fourier Transform Infrared technique. The ΔH values obtained for each solvent decrease as the solvation of stearic acid increaes. The results are relevant to the crystallization process of stearic acid from solution which may lead to different polymorphic forms depending on the different crystallization parameters.     

Evaluation of the Solution Stability When Reconstructing the Volume Particle Size Distribution from Small-Angle X-Ray Scattering Data for a Silicasol Solution

The results of studying the stability of the solution to the problem for determining the volume nanoparticle size distribution using experimental small-angle X-ray scattering (SAXS) data for a silicasol solution are presented. The possibility of reconstructing solutions using indirect Fourier transform and nonlinear minimization methods for a two-component model of spherical polydisperse particles has been investigated. The results obtained are compared with the simulation data obtained previously for theoretical data sets.     

Kinetics of a Single Crystal Growth from Supersaturated Liquid Solution. An Attempt on the Analytical Description of the State of Solution

The attempt was made at formulating a mathematical model describing the state of the supersaturated liquid solution circumfluenting a single crystal, as well as the transport processes occurring in that solution. As the result of a suitable computation procedure, numerical values of velocity components, concentrations, temperatures and the normal components of the mass flux in the vicinity of the crystal surface have been obtained.     

在卵磷脂溶液中仿生合成无定形碳酸钙

在含有卵磷脂的水溶液中仿生合成了无定形碳酸钙.所得样品用扫描电镜(SEM)、傅立叶红外光谱(FT-IR)、X射线衍射(XRD)和热重分析(TG)等分析方法进行了表征.研究表明:具有一定浓度的卵磷脂可以利用其端基磷酸根基团稳定无定形碳酸钙,这为理解在生物体内的环境中生物矿物的形成机理提供了一种新的途径.     

Growth of Barium Cerate Crystals from BaCl2 Solution

Barium cerate crystals of 1.5 mm diameter could be grown from melt solutions containing barium chloride, barium oxide (from thermolysis of barium carbonate), and cerium(IV) oxide. The maximum size of the crystals is limited by the low solubility of cerium(IV) oxide in the barium chloride melt (ca. 0.1 Mol%). The flux can be removed by leaching the melt with water. Acid solutions must not be used to avoid decomposition of the barium cerate crystals. Neither congruent melting or incongruent decomposition of the BaCeO₃ crystals could be found up to 1580 degrees centigrade.     

聚乙二醇用于注凝成型ZrO2坯体干燥研究

研究了注凝成型ZrO2坯体在聚乙二醇(PEG)溶液中的干燥过程,结果证明,随着PEG溶液浓度的增加,坯体脱水速度加快,平衡时残余水分降低;坯体固相含量越低,在PEG溶液中的脱水速度越快,干燥时间越短;随坯体尺寸增加,脱永速度降低,平衡时残余水分增高;注凝成型ZrO2坯体先在PEG溶液中脱水至平衡状态,再放置到空气中干燥,可以避免变形、开裂等缺陷的产生.     

Solution and solid-state hydrogen bond patterns ofo-methoxy- ando-ethoxybenzoic acids

The hydrogen bond patterns ofo-alkoxybenzoic acids have been shown previously to involve intramolecular hydrogen bonds. In this paper we show thato-methoxybenzoic acid (I) and o-ethoxybenzoic acid (II) both exist as monomers with intramolecular hydrogen bonds in solution but that, in the solid-state,I crystallizes as hydrogen-bonded dimers whileII crystallizes with an intramolecular hydrogen bond. The correlation between solution and solid-state hydrogen bond patterns is made using solution and solid-state IR and NMR methods and by correlating the solid-state patterns with known X-ray crystal structures. The crystal structure ofI is reported here. Crystal data: monoclinicP2₁/n;a=7.002(2),b=14.945(9),c=7.719(4) Å,=115.44(3)°,Z=4,V=729.4 ų, andR=0.046 (1660 reflections).     

二维铁电开关的Orihara-Ishibashi理论的精确解

将Orihara-Ishibashi铁电体统计理论用于二维正方形铁电薄膜,求出正方形铁电畴反转过程的体积比Q(t)和反转速率dQ/dt的解析表达式,并作了数值计算.结果表明,最大开关电流随系统尺寸l增大而上升,开关时间在系统尺寸l＜0.95时随l减小而下降,l＞0.95时随l减小略有上升.     

一种基于光子晶体的糖溶液检测仪的设计

为设计糖溶液浓度检测仪,由LiF和Si介质组成了一含缺陷层的光子晶体.在考虑两介质色散关系的基础上,利用传输矩阵法对其透射特性进行了研究,计算表明,此光子晶体在400～ 700 nm的范围内出现了一个透射率为1的缺陷模,此缺陷模有如下特征:缺陷层中糖溶液浓度变化,不影响缺陷模的透射率和半峰全宽度,只改变缺陷模的中心位置,且糖溶液浓度与缺陷模的中心波长呈线性关系.两介质几何厚度分别或同时增加,缺陷模的透射率和半峰全宽度均不变,但其中心位置红移,移动率分别保持不变;LiF单独变化时,中心位置的移动率最小,LiF和Si同时变化时,移动率最大.不同介质几何厚度变化时,糖溶液浓度与缺陷模的中心波长呈不同的线性关系,但可通过重新定标来确定.     

Systematic Solution of the Mean Field Equation for Liquid Crystals

Starting with a pairwise, spatially and orientationally dependent intermolecular potential of the Kobayashi-McMillan form, we carry out a systematic solution of the mean field equation for liquid crystals. The mean field equation, presented as first of a hierarchy of BBGKY equations, is first reduced to a set of coupled integrodifferential equations by means of expanding the distribution function f (r, δ) and In f (r, δ) in Legendre polynomials and the reciprocal lattice space. In the first level of approximation, the expansion retains only the lowest-order coefficients, permitting a complete decoupling of the equations. In the second level of approximation, the leading coefficient which couples spatial order to orientational order is included. In the third level of approximation two more higher order coefficients are included. At each level, the free energy functional is evaluated to determine the equilibrium phase at given temperatures and chainlengths of a homologous series. It is shown that the expansion converges very rapidly, the second level of approximation being entirely sufficient. This lends support to our earlier variational calculation which contained only three variational parameters.     

Determination of Nucleation Parameters of YBCO from High Temperature Solution

The growth kinetics of YBCO single crystal from high temperature solution of YBCO-BaO/CuO solute-solvent system has been studied. Based on regular solution model and classical nucleation theory the thermodynamical data investigated for the system are used to determine the nucleation parameters: interfacial energy, metastable zone-width (supercooling temperature), free energy change, critical nucleation radius etc. which leads to the understanding of the nucleation phenomena of YBCO.     

L-精氨酸掺杂下ZTS溶液的稳定性研究

研究了L-精氨酸掺杂下硫脲硫酸锌(ZTS)溶液中的成核过程,测量了在不同掺杂浓度下ZTS溶液的亚稳区和诱导期.结果表明:随掺杂浓度的增加,溶液的亚稳区变宽,诱导期增大;根据经典成核理论计算了晶体的成核热、动力学参数,分析了溶液稳定性与掺杂浓度的关系,即随着L-精氨酸掺杂浓度的增加,溶液的稳定性得到明显提高.利用化学腐蚀法对ZTS晶体(100)面进行了腐蚀,并用光学显微镜对腐蚀面进行观察,得到了清晰的位错蚀坑.当L-精氨酸掺杂浓度为1.5mol;时,ZTS晶体(100)面位错蚀坑密度最小,适合高光学质量晶体的生长.     

Chiral Symmetry Breaking in Sodium Chlorate Crystallization from Unstirred Solution

Statistics of nucleation of chiral forms of sodium chlorate from unstirred, achiral solutions was studied. The trimodal distribution of enantiomers was obtained in which apart from the peak for the same probability of the creation of L and D crystals, two other maxima for the large enantiomeric excesses of L and D forms were present. The first nucleated crystals govern the handedness of the secondary crystals and the formation of pure enantiomers and high enantiomeric excesses in crystallization from unstirred, unseeded solutions are caused by the process of chiral symmetry breaking rather than statistical fluctuations.     

Solution epitaxy of patterned ZnO nanorod arrays by interference lithography

Aligned ZnO nanorods with controllable size and tunable pattern pitch were grown at 90 °C in aqueous solutions by employing a nano-pattern fabricated by interference lithography. This method gave perfectly c-axis aligned ZnO nanorods arrays. The optical properties are significantly enhanced by a post-growth treatment combining thermal and plasma treatments. The photoluminescence intensity of the UV emission peak is increased more than 100 times after the post-growth treatments which also led to the occurrence of lasing from the nanorods.