L-天门冬氨酸对三水碳酸镁晶体合成的影响研究

依据仿生合成的原理,选择无水MgCl2和无水Na2CO3作为反应原料,通过L-天门冬氨酸和五种无机表面活性剂分别对晶体生长进行调控,应用XRD、SEM对晶体的物相组成以及形貌结构进行表征.试验结果表明当表面活性剂为L-天门冬氨酸时,晶体生长效果最佳.又通过以L-天门冬氨酸添加量和体系pH值为参数变量进行研究,结果表明L-天门冬氨酸质量分数为0.15;,体系pH为9.5为最佳条件,有毫米级束状三水碳酸镁晶体的生成,并对L-天门冬氨酸在仿生合成三水碳酸镁过程中的作用机理进行了初步探讨.     

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.     

聚丙烯酰胺/硬脂酸协同改性半水硫酸钙晶须及其形貌稳定性研究

使用聚丙烯酰胺/硬脂酸改性体系对半水硫酸钙晶须进行表面改性,研究聚丙烯酰胺的加入对改性过程中硫酸钙晶须的稳定化影响.通过显微镜观察晶须产品的形貌,利用X射线衍射仪分析其相组成,利用傅里叶红外光谱仪检测晶须产品的表面基团.结果 表明:聚丙烯酰胺/硬脂酸协同改性硫酸钙晶须的晶体形貌及相组成未发生改变,较硬脂酸单一改性后的晶须长径比有所上升,且在水溶液中形貌保持时间延长,改性后晶须的活化指数、接触角较硬脂酸单一改性有明显上升,实现了硫酸钙晶须改性过程中的稳定化处理.     

硬脂酸/插层高岭石复合相变材料的制备和热性能研究

高岭石(K)是一种常见的黏土矿物,具有低成本、阻燃、多层结构等固有优点。本文采用真空浸渍法将硬脂酸(SA)吸附到插层高岭石(IKL)和二甲基亚砜(DMSO)复合物的孔隙中来制备用于储热的复合相变材料。通过X射线衍射(XRD)、红外光谱(FT-IR)、热重分析(TG)、差示扫描量热法(DSC)、扫描电子显微镜(SEM)和比表面积分析仪(BET)表征了复合材料的热性能、结构和主要组分。由于插层复合物形成后高岭石层间距增大,对SA的吸附率达到32.3%,熔化和凝固潜热值分别为43.36 J/g和43.16 J/g,熔化和凝固温度分别为51.9℃和51.7℃。此外,该复合相变材料具有较好的热稳定性。由于SA/IKL复合相变材料具有高吸附量、高潜热、良好的热稳定和低成本等优点,因此,其在实际的应用中具有潜在的价值。     

不同溶剂对合成堇青石粉体结晶性能的影响

以硝酸镁、硝酸铝、正硅酸乙酯作为原料,通过液相法合成堇青石粉体,研究不同溶剂以及体系pH值对合成堇青石粉体结晶性能的影响.利用DTA-TGA、XRD测试手段对粉体进行表征,结果表明:以水为溶剂,体系pH=4时,在1000 ℃时,衍射图谱相对比较平滑,开始生成μ-堇青石以及尖晶石,在1200 ℃,μ-堇青石及尖晶石的衍射峰强度开始降低,开始有α-堇青石生成,在1250 ℃,μ-堇青石的峰基本消失不见,而α-堇青石的峰强度升高,在1350 ℃时,α-堇青石相增多,几乎全部转化为α-堇青石.     

Cadmium Incorporation in the Crystallization of Calcium Sulfate Hemihydrate from Phosphoric Acid

Semi-batch crystallization experiments of CaSO₄ · 1/2H₂O(HH) were performed in concentrated phosphoric acid at various H₂SO₄ contents in the absence and presence of additives. The influence of the operating conditions and additives on the cadmium and phosphate incorporation in the HH lattice were determined. The Cd uptake increased with raising H₂SO₄ content. Addition of HNO₃ caused a reduced cadmium and phosphate incorporation. Addition of iodide also lowered the cadmium incorporation. The obtained results fits into a model for the incorporation of foreign ions during crystal growth. According to this model the incorporation is primarily a kinetically controlled process.     

Polymeric AdditiveS' Effect on Crystallization of Calcium Oxalate Scales

Laboratory studies concerned with the effects of polymeric additives on the crystallization of calcium oxalate dihydrate and calcium oxalate monohydrate are described and the results obtained are discussed. These compounds are major components of scales formed in some Australian sugar mills. The studies involved the measurement of crystallization induction periods and rates, in the presence and absence of additives. Crystal morphologies were also examined. A range of experimental conditions were employed, from studies in pure solutions of the lattice ions to those more directly comparable with the mill operation.     

蒸发电流对CdSe薄膜的结晶性能影响研究

采用真空热蒸发技术,选取系列蒸发电流在光学玻璃基底上制备出CdSe薄膜.利用X射线衍射仪、扫描电子显微镜和原子力显微镜对样品的结构和表面形貌进行了表征.结果显示:蒸发电流为75 A时,CdSe薄膜沿(002)方向择优生长,衍射峰较强,半峰宽较小,晶粒(约48 nm)分布较均匀,表面粗糙度低(5.58 nm),无裂纹.蒸发电流不改变薄膜的结晶取向,但电流过低时,薄膜的表面颗粒轮廓模糊且有间隙,结晶性差;电流高于75 A时,随电流升高,薄膜结晶性逐步降低,颗粒变小,半峰宽变大,部分样品表面晶粒生长不完整,表面出现裂纹.     

晶化时间对M型钡铁氧体吸波性能影响

以Fe(NO3)3·9H2O、Ba(NO3)2、NaOH为原材料,添加表面活性剂聚乙二醇,采用水热法成功合成M型钡铁氧体.采用X-射线衍射仪、扫描电镜和矢量网络分析仪对样品进行表征分析,研究了水热法中晶化时间对样品的粒度、形貌以及吸波性能的影响.试验结果表明:在Fe/Ba摩尔比为8、晶化时间8h制备的纯相M型BaFe12O19,样品结晶完整,形貌为六角片状,平均尺寸在1 ～2 μm.在1～18 GHz频段宽内,损耗因子在13.24 GHz处达最大值为0.33,吸波反射率为-10.35 dB,吸波性能最好,提高了钡铁氧体在Ku波段范围内的吸波性能.     

Effect of Selected Parameters on Crystallization of Copper Sulphate Pentahydrate

Different batch cooling modes (quick and slow cooling with constant cooling rate, program-med cooling with nearly constant supersaturation) of copper sulphate aqueous solutions have been studied in order to find best conditions for the investigation of the effect of additives on crystallization. Three types of additives (solvents, ionic substances and surfactants) have been used and their effect on crystal size, habit and yield was studied.     

Effect of Crystallization Front Shape on the Dislocation Density in Germanium Single Crystals

Crystallography Reports - The effect of crystallization front shape on the dislocation density in Ge single crystals with a diameter of 100 mm, grown by the Czochralski method, has been studied....     

NaF对黄磷炉渣微晶玻璃析晶的影响

以自然冷却黄磷炉渣为原料,外加一定量的SiO2和Al2O3,以及不同比例的NaF,通过熔融法制备黄磷炉渣微晶玻璃.利用差热分析仪(DTA)、X射线衍射仪(XRD)、扫描电子显微镜(SEM)等分析手段,并借助Kissinger方程分析NaF对黄磷炉渣微晶玻璃析晶的影响.结果 表明:随着NaF添加量的增大,基础玻璃的析晶活化能E先减小后增大,当添加5wt;的NaF时,黄磷炉渣基础玻璃的析晶峰温度值最小,析晶活化能E最低,析晶效果最佳;微晶玻璃的主晶相不会随NaF添加量的增大而改变,主晶相均为硅灰石(CaSiO3).     

硼酸在合成La-Yb-Er体系发光材料中作用的研究

本文通过共沉淀的实验工艺,以La2O3为基质,Er3+离子为发光中心,Yb3+离子为敏化中心,在前驱体的烧结过程中加入不同量的H3BO3,制备了La-Yb-Er体系发光材料,实验结果显示在1300℃的温度条件下,硼酸的加入量为前驱体总量的1/5～1/3时,烧结后得到以发红光为主的上转换发光材料,并对作用机理进行分析.     

铝膜溅射功率对铝诱导CdZnTe薄膜结构及性能影响

采用磁控溅射法制备CdZnTe先驱薄膜/金属Al膜的层叠结构,利用铝诱导技术制备CdZnTe薄膜.通过原子力显微镜、X射线衍射、Raman光谱仪和半导体特性分析系统,研究了铝膜溅射功率对铝诱导CdZnTe薄膜结构及性能的影响.结果表明:随着铝膜溅射功率的增加,铝诱导CdZnTe薄膜表面的薄膜结晶质量、晶粒尺寸和薄膜电阻率先增大后减小.铝诱导晶化的效果与铝膜溅射功率有关,当铝膜溅射功率达到100 W,CdZnTe薄膜的晶化诱导效果最显著,薄膜结晶质量最好,晶粒尺寸最大.     

The Synthesis and Crystal Structures of the Homologues of Epalrestat

Journal of Chemical Crystallography - Two homologues of epalrestat were synthesized and characterized by IR, MS, elemental analysis, 1H NMR, 13C NMR and their crystal structures were determined by...     

热处理制度对透辉石微晶玻璃析晶与导热性能的影响

以SiO2、CaO和MgO为主要原料,采用传统高温熔融工艺制备了基础玻璃,并通过一步析晶热处理工艺制备了透辉石微晶玻璃.利用X射线衍射仪、电子扫描显微镜和激光导热仪分别研究了热处理温度和时间对透辉石微晶玻璃析晶和导热性能的影响.结果表明:随着热处理温度的升高,微晶玻璃的结晶度增加,晶粒尺寸增大,导热系数先增大后减小;随着热处理时间的延长,微晶玻璃的晶粒尺寸增大,导热系数先增大后减小.当热处理温度890℃,热处理时间120 min,升温速率为10℃/min,微晶玻璃晶粒尺寸为0.3～0.4μm,结晶度为79;,导热系数达到最大值2.59 W/(m·K).     

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.     

铬渣对黄磷炉渣微晶玻璃析晶的影响

以自然冷却黄磷炉渣为基础原料,外加适量的SiO2和不同比例的铬渣,熔融法制备黄磷炉渣-铬渣微晶玻璃.通过差热分析(DTA)、X射线衍射(XRD)和扫描电子显微镜(SEM)等技术手段分析铬渣添加量对黄磷炉渣-铬渣微晶玻璃晶化行为的影响.结果 表明:随着铬渣添加量的增大,基础玻璃的析晶活化能E先减小后增大,当铬渣的添加量为20wt;时析晶活化能E最小,析晶能力最佳;微晶玻璃的主晶相不会随铬渣添加量的增大而改变,主晶相均为硅灰石,在实验添加量的范围内,制备的黄磷炉渣-铬渣微晶玻璃毒性浸出浓度远低于国家标准规定的最高允许浓度.     

Differential Thermal Analysis Studies on the Crystallization of Strontium Tungstate from Sodium Tungstate Melts Thermodynamic and Kinetic Parameters

From the estimated diffusion rate-constants (k_D1) of strontium tungstate crystal growth from sodium tungstate melts in platinum crucibles, energy (E), enthalpy (ΔH_a), entropy (ΔS_a) and free-energy (ΔG_a) of activation and the pre-exponential factor (k₀) for the process were estimated using an ordinary Arrhenius equation k_Dl = k₀e^−E/RT. These thermodynamic parameters were virtually unaffected by the changes in crystallization temperatures (T₀) and cooling rates (R)_T. The distance (r₁₂), between a diffusing species and its host necesary for a successful diffusion, increased with T₀ and T_T but there was no direct correlation.     

Ge覆盖层诱导晶化多晶Si薄膜的晶化特性研究

采用电子束蒸发技术在衬底温度为180℃条件下生长具有Ge覆盖层的非晶Si薄膜,并于500℃、600℃、700℃真空退火5h.采用Raman散射、X射线衍射(XRD)、全自动数字式显微镜等对所制备薄膜的晶化特性进行研究.结果表明,Ge覆盖层具有诱导非晶Si薄膜晶化的作用,且随着退火温度的升高a-Si薄膜晶化越显著.具有Ge覆盖层非晶薄膜经500℃退火5h沿Si(400)方向开始晶化,对应晶粒尺寸约为4.9 nm.将退火温度升高到700℃时,非晶硅薄膜几乎全部晶化,晶化多晶Si薄膜在Si(400)方向表现出很强的择优取向特性,晶粒尺寸高达23.3μm.与相同条件下制备的无Ge覆盖层的非晶Si薄膜相比,晶化温度降低了300℃.