The Morphology of Hydrothermally Grown Plagioclase

Plagioclase crystals Ab₂₀An₀₀ and nearly pure anorthite were grown on the surface of artificial melts by hydrothermal treatment at 2 kb. The average crystal size was 0.002 to 0.008 mm. In the temperature range of 400° to 600°C a pseudohexagonal habit was observed for anorthite while a lath-like habit due to the prevalence of {010} was found for the Ab₂₀An₈₀ composition. Dominating faces are {010} {130} {110} {100} {110} {130} in the zone [001] and {021} {111} {111} {021} {111} {111} together with {001}.     

水热法ZnO晶体特征研究

ZnO具有优良的综合性能使其成为极有前途的下一代光电材料,水热法是一种重要的生长ZnO晶体的方法.本文对水热法生长的面积约150mm2的ZnO晶体进行了报道,研究了晶体不同方向的生长速度、形貌特征和光学性能.X射线摇摆曲线表明晶体的质量较好.对于光学性质的分析表明晶体生长时加入H2O2能显著提高晶体的质量.494nm附近的发光带可能与氧空位有关.520nm的发光可能与Na或者Si所形成的杂质能级跃迁有关.     

水热法白宝石晶体和籽晶界面研究

用分光光度计研究发现水热法白宝石晶体和籽晶界面使晶体透过率降低,用大视场偏光显微镜和原子力显微镜分析了该界面的包裹物分布以及界面的显微结构.结果表明平行于(1123)面的籽晶和生长层晶体界面包裹物含量少.界面的缺陷主要来自于晶格畸变及生长初期的温场不稳定所引起的结构缺陷,这也是引起晶体透过率下降的主要因素.     

The Morphology of Some Hydrothermally Synthesized Li-Minerals: A-Zeolite, α-Eucryptite, β-Spodumene and β-Eucryptite

The hydrothermal treatment of glass with the composition 2 LiF, Al₂O₃, 3 SiO₂ at 1 kbar in the range of 150 °C to 850 °C gave rise to the formation of A-zeolite with orthorhombic unit cell with å = 10.31 Å/b̊ = 8.18 Å/c̊ = 5.0 Å (space group Pna2₁), α-eucryptite, trigonal, å = 13.4 Å/bº = 13.4/Å/cº = 9.0 Å (space group R 3 ), β-spodumene, pseudocubic/tetragonal, å = 7.53 Å/b̊ = 7.53 Å/c̊ = 9.15 Å (space group P4₃2₁2), β-eucryptite, monoclinic, å = 7.75 Å/b̊ = 5.2 Å/c̊ = 11.16 Å (space group P6₂22). The morphology and development of the mineral phases depend on the temperature of formation.     

锌铬尖晶石水热合成及形成机理研究

采用水热法制备了纳米ZnCr2 O4晶粒.采用X-射线衍射(XRD)、透射电子显微镜(TEM)和红外光谱仪(IR)研究了晶粒的物相演化规律.结果表明,在180℃温度下可制备2 nm的ZnCr2O4晶粒.ZnCr2 O4晶粒的形成遵循溶解-结晶机制,铬的三聚体和含有羟基的四配位锌的聚集体形成与Al13结构相同的ZnCr12,这些ZnCr12晶核经过进一步缩聚反应形成ZnCr2O4晶粒.     

利用锌渣氧粉碱驱晶化法制备纳米氧化锌紫外吸收剂

以硫酸为浸出剂,提取锌渣氧粉中的锌,形成精制ZnSO4溶液为锌源,NaOH溶液为沉淀剂,采用低温开放溶液法制备出纳米氧化锌,研究锌碱摩尔比、反应温度、不同初始锌离子浓度对产品晶体结构和形貌的影响,确立控制条件:初始Zn2+浓度0.1 mol·L-1,锌碱摩尔比1:5,控制62℃条件下恒温搅拌反应1 h,制备出锥形的六方晶系纤锌矿结构纳米氧化锌,颗粒分布均匀,平均粒径为100 nm.ZnO的形成是以负离子四面体ZnO2-2为生长基元,由Zn(OH)2到ZnO"结晶-溶解-再结晶"过程.制备的氧化锌在紫外光区280～400 nm波段有很强的吸收性,在可见光区有较好的透过率,具有良好紫外光遮蔽性和可见光透过性,可作为紫外线吸收剂使用.     

X-ray Lang Topography and Infrared Spectroscopy in Quartz Crystals Grown Hydrothermally with Intermittent Runs

Growth defects in Y-plates obtained from Y-bar synthetic quartz crystals, grown hydrothermally with intermittent runs, have been studied for the first time by X-ray Lang topography and infrared spectroscopy. To study the effect of interfaces on dislocation structures, the growth runs have been discontinued several (6 to 7) times by switching off the autoclaves from 30 min to 1 h. The dislocations were observed to change their directions at the generated interfaces, sometimes they stop at the in terfaces or move straight through the interfaces depending on the angles of the interfaces which are presumably low-angle grain boundaries. The percentage transmission of infrared beam has also been measured as a function of the distance traversed in the crystal. The inverse anelastic loss (Q) decreases at the interface which is due to the greater accumulation of chemical impurities and H bonded OH⁻ ions at these interfaces. The effect of in-situ electric field on the topographic contrast has also been studied which reveal some interesting results on account of space charge polarization.     

Yb：YAl3（BO3）4晶体形貌与生长速度的关系

观察测量了不同生长速度（相应于不同降温速度）自发成核生成的Yb:YAl3(BO3)4晶体形貌。粒试较大（＞2mm)的晶体不管降温速率快慢形态都很简单,只发育六方柱（1120）和菱面体（1011）,粒度较小（＜2mm)的晶体形态随降温速率增快而变复杂,发育一些罕见的高指数晶面,说明在生长速率较快的条件下,在晶体生长早期,一些高能面发育,在晶体生长后期已尖灭了,晶体生长的大部分时间是在低能面（1120）和（1011）上进行的,对比了不同生长条件下晶面的粗糙度,随着降温速度的增快,六方柱面（1120）和菱面体面（1011）由光滑变粗糙,顶面（0001）永远是粗糙的,从晶体结构上定性地探讨了3种晶面的杰克逊因子a及生长机理。     

The Effect of Solid and Liquid Inclusions on Morphology of Crystallization Front

The interaction between crystallization front and solid particles was studied for substances characterized by the normal growth mechanism (continuous growth). It has been measured the critical velocity below which the particle of radius R is repulsed by moving interface and above it is captured. It has been shown that critical velocity is proportional to R⁻(1.4–1.8) what satisfactorily agrees with Chernov-Temkin's theory. Data have been received about change of interface morphology at capture of solid particles for growth from pure and impurity-contained melt. The dendrites have been found to split at interaction with particles and concentration inhomogeneities. Taking for example Al-Cu alloy, possibility has been shown to disperse the dendritic structure by formation concentration inhomogeneities in the melt.     

The Growth Kinetics and Surface Morphology of GaN Epitaxial Layers on Sapphire

The growth kinetics of GaN on Sapphire was analyed on the base of some experimental data such as: the growth rate temperature depandence, on the base of some experimental data such as: the growth rate temperature dependence, the grwoth rate dependence on the gas flow velocity, the growth rate depandence on the crystallographic and spatial orientation of the substrate. The limiting stage of the epitaxy process was established at different growth conditions. The morphology of GaN epitaxial layers obtained at these conditions is described.     

Morphology of polycrystalline cassiterite films

Polycrystalline cassiterite films have been grown by the hydropyrolytic method from a 10(H₂O) + 5(SnCl₂ · 2H₂O) solution (in weight fractions) on corundum substrates. The crystallization regularities are considered and a comparative analysis of the properties of natural and artificial cassiterite crystals is performed. The surface morphology is investigated and the size of crystalline grains is determined by scanning electron microscopy. X-ray microprobe analysis showed that all films contain tin and oxygen atoms in a ratio corresponding (within the experimental error) to the chemical formula of tin dioxide. It is established that the surface morphology of cassiterite films is characterized by both single crystallites and aggregates of two or more crystals typical of twins. It is suggest that doping can efficiently be used to control the concentration of twins and the stability of their formation.     

The Phase Morphology of 2,5 DI-Substituted Pyridine Derivatives: A Quantum Mechanical Analysis

A comparative analysis of some mesogenic and nonmesogenic molecules of 2, 5 di-substituted pyridine derivatives molecules has been carried out. The multicenter multipole expansion method is used to obtain the various interaction energy terms. The phase morphology of the mesogenic molecular system has been further investigated with the aid of various energy terms of configurations. The multicenter multipole expansion method is satisfactory and predicts the mesogenic behavior of molecular systems.     

The Relation between Structure and Morphology of Magnetoplumbite-type Crystal LaMgAl11O19

The magnetoplumbite crystal LMA is grown by the CZ technique. The orientations of all developing facets on the crystals are determined by means of X-ray and optical methods, and Miller indices are calculated. According to the PBC theory, the relations between the morphology of LMA crystal and its structure are explained.     

Morphology of BBO Crystals and their Inclusions

This paper reports on the morphology and inclusions in the low temperature phase barium metaborate BaB₂O₄(BBO) crystal grown by an improved flux pulling method. The morphology of ideal BBO crystals and the relationship between the faces and the growth rate are given. The result that BBO has the symmetry L₃3P and belongs to the space group C_3v−3m can therefore be concluded. It is found that the polarity of the BBO crystal along the Z (or c) axis has a visible influence on the morphology. The investigation of the inclusions in BBO crystals shows that these have a six-fold symmetry which corresponds to the extension of flute-like facets. It is also found that most of the inclusions have a regular geometric figure and can be regarded as the negative-crystal structure which is due to the internal growth mechanism.     

Morphology control of MSU-1 silica particles

Mesoporous silica, MSU-1 with spherical morphology was prepared using TEOS (tetraethylorthosilicate) as a silica source in the presence of an alkyl polyethylene oxide surfactant via the novel two-step process proposed by Prouzet’s group: hydrolysis of TEOS conducted in highly acidic condition at room temperature followed by condensation promoted by fluoride salt addition at 35 °C. The particles produced were characterized by XRD, SEM, and N₂ adsorption/desorption isotherm. Static condensation period was found to be essential to have spherical morphology. Growth of spherical particles and evolution of porosity were studied as a function of time, temperature, NaF/TEOS, and TEOS/surfactant ratio. The MSU-1 particles prepared under different synthesis conditions were briefly tested for chromatographic separation of selected organic molecules, which demonstrates the governing influence of the pore size in MSU-1 on retention time.     

分子晶体马来酸氢十六酯的形貌分析

本文根据晶体结构数据,应用周期键链理论,分析了标题化合物的晶体形貌及生长习性,并应用原子-原子势能函数方法,用turbo c编程计算了各显露面的晶面接触能.结果表明,晶体中属于F面的单形有{001};属于S面的单形有{010},{100},{110}.由晶面接触能的大小可知该晶体成薄板状.理论分析与实际情况符合的较好.