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.     

Study of the Solution Stability in the Analysis of Polydisperse Systems by Small-Angle Scattering

The stability of the solution to the problem of restoring the volume size distribution of nanoparticles for theoretical small-angle scattering data sets calculated within six different models has been investigated. The influence of the data noise level on the deviation of the found solution from the specified theoretical model is analyzed. Recommendations on the optimal search scheme of size distributions for complex polydisperse systems are given.     

Small-angle X-Ray analysis of macromolecular structure: the structure of protein NS2 (NEP) in solution

A complex structural analysis of nuclear export protein NS2 (NEP) of influenza virus A has been performed using bioinformatics predictive methods and small-angle X-ray scattering data. The behavior of NEP molecules in a solution (their aggregation, oligomerization, and dissociation, depending on the buffer composition) has been investigated. It was shown that stable associates are formed even in a conventional aqueous salt solution at physiological рН value. For the first time we have managed to get NEP dimers in solution, to analyze their structure, and to compare the models obtained using the method of the molecular tectonics with the spatial protein structure predicted by us using the bioinformatics methods. The results of the study provide a new insight into the structural features of nuclear export protein NS2 (NEP) of the influenza virus A, which is very important for viral infection development.     

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.     

锡溶液中半导体单晶CuSi2P3的生长与结构分析

Single crystals of CuSi2P3 as long as 1cm has been grown by using tin solution growth. X-ray powder photography technique showed that only CuSi2P3 can grow as a pure material without any exchanges of Si with Sn. The structure is in the form of Fcc with a lattice parameters of a=0.5248nm. Electron probemicro anaiysis (EPMA) has supported the X-ray data in regarding the single phase of this compound grown by solution growth.     

Investigation of the Solution Status of TGS and ATGSP Crystals

This paper reports on the solubility curves of TGS and ATGSP crystals with different pH's. The relationship of (010) growth rate in solutions with different pH varied with the supersaturation, has been studied. The influence of pH on the metastable region of solution have been measured. The experimential results are discussed with respect to the structure and viscosity of solution and the solubility of the crystals. Finally the optimum conditions for the rapid growth of TGS and ATGSP crystals is given.     

化学溶液法制备涂层导体过渡层La2Zr2O7厚膜的研究

为制备高质量的双轴织构La2Zr2O7(LZO)涂层导体过渡层,本文采用化学溶液法(Chemical solution deposition,简称CSD法),以乙酰丙酮镧和乙酰丙酮锆为溶质,丙酸为溶剂配制成前驱盐溶液,在立方织构的Ni-5 at;W基底上用快速一步法退火工艺制备了LZO种子层及双层LZO厚膜.SEM观察种子层呈岛状均匀排列,符合种子层形貌特点.XRD结果显示0.06 mol/L浓度种子层上制备的LZO厚膜具有很强的双轴立方织构,其中(222)面Phi扫描和(400)面摇摆曲线半高宽值分别为6.37°和5.82°.SEM观察发现120 nm厚的LZO薄膜表面平整,无裂纹,为后续沉积YBCO提供了很好的模板.     

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.     

On the shape of the phase boundary of melt-grown ribbon-shaped crystals

Approximated analytical solution of the stationary Stefan problem for the ribbon crystals pulled from the melt are obtained. The results of calculation of the crystallization front are compared with the numerical solution obtained by finite elements method. The good coincidance is demonstrated.     

Influence of Gravitation on the Processes of Heat and Mass Transfer in Solution Crystal Growth by the Travelling Heater Method (THM) (II)

The two-dimensional quasi-stationary thermodiffusive hydrodynamic problem of the crystal PbTe growth from solution by the travelling heater method has been solved. Computation is given for the temperature field distribution in crystal and solution. The picture of fluxes in solution was obtained under free convection for different lengths of solvent zone. It is shown that in the absence of absence of gravitation at the growing interface in solution there occurs a constitutional supercooling, whereas the free convection removes it, which leads to greater morphological stability of a growing crystal face.     

Treatment of data on metastable zone width leading to nucleation characteristics and measurements in the system potassium dichromate-water

Measurements of the width of metastable zone can be used for characterisation of the kinetics of nucleation. Methods of treatment these data discussed in literature are summarised, re-examined and arranged in order to enable smoothing of experimental data and simultaneous calculation of the values of certain characteristic nucleation parameters. An example (potassium dichromate in aqueous solution) shows that the values obtained in this way are within usual limits given in the literature. The results indicate that in unseeded solutions the nucleation was probably heterogeneous one, whereas in presence of a fixed seed an adsorbed layer mechanism of secondary nucleation followed by a fluid shear action seems to explain the results.     

Influence of Gravitation on the Processes of Heat and Mass Transfer in Solution Crystal Growth by the Travelling Heater Method (THM) (I)

In axially symmetric and planar cases the formulation is given of a two-dimensional hydrodynamic thermodiffusive problem on the crystal PbTe growth from solution by the travelling heater method. The analysis of the one-dimensional thermo-diffusive problem solution is presented. The dependences were obtained of the growing and dissolving interface positions relative to the heater on the heater travel rate for different lengths of solvent zone.     

Investigation on the Aqueous Solution for Growth of Bimetallic Thiocyanate Complex Crystal Materials

The stability of cadmium mercury thiocyanate (CMTC) crystal growth solution was mainly discussed. The effects of temperature, pH value, time and KCl concentration on CMTC crystal growth were investigated. The effects of pH value and KCl concentration on crystallization habit of CMTC were also studied. The results show that when pH value ranges from 2.5 to 3.8, the solution is relatively stable, under the condition of pH ≤ 2.0 or pH ≥ 4.0, the solution has poor stability and some powder appears. The solution becomes unstable at high temperatures. When the concentration of KCl is more than 27% there has not generated CMTC crystal in the solution, a new kind of material produced from solution. The pH value and KCl concentration affect crystalline morphology of CMTC crystal.     

Solution growth of metal-organic complex CuTCNQ in small dimension interconnect structures

In this paper, we report two different elaboration routes to grow metal-organic complex CuTCNQ in liquid phase within small interconnect structures (i.e. via holes opened in SiO₂/SiC stack). The basic common idea relies on the formation of CuTCNQ material from the partial corrosion of a Cu bottom electrode by a TCNQ-based solution. The two solution growth methods are compared in terms of (i) via holes filling; (ii) local microstructure of CuTCNQ complex and (iii) quality of interface between CuTCNQ and copper metallic electrode. In the first route, in the reaction of the substrate with a TCNQ/copper salt solution in acetonitrile/toluene, a rapid formation of porous CuTCNQ complex is observed with an over-growth outside interconnect structures and many voids within via holes and at the interface with Cu layer. In contrast to this “mushroom-like” growth, the reaction of the substrate with a TCNQ solution in acetonitrile/2-butanone results in a “crystal-like” dense CuTCNQ complex within via holes and a CuTCNQ/Cu interface free of voids. In the latter case, satisfactory electrical performances are expected for future resistive switching memory devices.     

Phase Diagrams of Semiconducting Compounds (III) Thermodynamic Calculation of the Ternary Melting Diagram of Ga?Al?As

The ternary phase diagram of Ga Al As has been calculated by VIELAND 'S method. The activity coefficients are determined using DARKEN 'S quadratic formalism for a ternary liquid in equilibrium with a regular solid solution. The agreement of calculation and experimental results is examinated using data from literature and solution measurements and liquid phase epitaxy experiments of this paper.     

On the kinetic of crystallization of zinc oxalate (II). Determination of the specific surface energy at the crystal solution interface by kinetic studies

An apparatus based on turbidimetry was constructed for studying the kinetics of crystallization of sparingly soluble salts. The kinetics of crystallization of zinc oxalate was investigated at various supersaturations and pHs of the medium. The specific surface energy at the crystal-solution interface was determined from the induction periods of the S-shaped curves by means of the classical theory of nucleation. The calculations were made using the slope of the logarithmic dependence of I or τ, respectively, on supersaturation (equations 1 and 2) and the critical supersaturation which was also determined on the basis of kinetic data. Various values of σ were found for the different supersaturations. Different values for this quantity were also obtained when supersaturation was presented by the concentration ratio (S = C/C₀) or by the ratio of the product of the two ions concentrations in the supersaturated solution to that in the saturated one (S = ab/L_p). These σ values were lower than those obtained using the critical supersaturations at the two different solution pHs. For the present it is impossible to give a definite explanation of the results obtained. The experiments for determining the specific surface energy at the crystal-solution interface will be continued.     

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.     

A Study of the Metastable Zone in Nylon 12-Toluene Solution

The metastable zone for a nylon 12-toluene solution was determined in an established constant cooling rate apparatus. Supersaturation solubility curves and the equilibrium solubility curve are unparallel one to another. The metastable zone width under seeded conditions is dependent on the cooling rate, the retention time and the saturation temperature. And the metastable zone width under unseeded conditions is dependent on the cooling rate, the agitation rate and the saturation temperature. Through constant cooling rate crystallization experiments, two empirical correlations pertaining to the metastable zone of the solution have been found.     

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.