工业晶体生长

本文考察了一些典型的晶体材料及其工业生长技术,如提拉法生长硅单晶,水热法生长水晶,VGF法生长GaAs,下降法生长锗酸铋,壳熔法生长锆石等,探讨了工业晶体生长的特点和发展方向.     

微下拉晶体光纤生长设备研制及YAG单晶生长

介绍了一种新型单晶生长技术(微下拉:micro-pulling-down),并概述了该方法在Nd∶ YAG单晶光纤生长方面的应用及发展.率先在国内开展了微下拉单晶生长炉的研制工作,填补了该领域的空白.同时,生长了直径3mm,长度100 mm、300 mm的Nd∶ YAG单晶,晶体整体透明、内部无散射点,表现出了良好的单晶性,有望作为激光工作物质使用.     

Growth Rate Effects during Indium-Antimony Crystal Growth

Local interface velocities are tracked radioscopically in the III-V semiconductor compound indium-antimony grown in a vertical Bridgman-Stockbarger furnace. Comparisons are made of interface velocities from five different compositions (40, 49, 50, 55, and 60 at.% Sb). Under specific growth conditions, the growth velocity for stoichiometric melts was comparatively constant and very close to the translation velocity. Measured chemical homogeneity was excellent, though polycrystallinity could occur when concentration boundary layers formed ahead of the interface. Off-stoichiometric melts exhibited initial supercooling, resulting in transient interface velocities and polycrystallinity. The observed supercooling is governed by chemical segregation in the melt. Thus, local growth velocity fluctuations are unambiguously attributed to a coupling of ompositional effects in the melt and crystal facetting kinetics.     

绿柱石晶体的水热法生长及特征研究

采用温差水热法,以分析纯的Al(OH)3和BeO以及无色纯净的石英为原材料,球形和//s(1121)的片状无色绿柱石为籽晶,在复杂的盐酸混合溶液中生长了无色透明的绿柱石晶体.利用双圈反射测角仪、电子探针、X射线衍射仪和红外光谱仪等仪器,对合成绿柱石晶体的形态、成分及晶体结构进行了详细的研究.结果表明,合成的绿柱石晶体为六方短柱状,主要发育平行双面c{0001}、六方柱m{1010}、a{1120}和六方双锥p{1011}四种单形.合成的绿柱石晶体的成分中(Na2O+ K2O)的质量分数约为0.59;,且c0/a0值为0.9988,可归属于"正常"绿柱石向"四面体"绿柱石的过渡范畴.在中性或弱碱性环境体系中,通过调整绿柱石中各成分的百分含量,有望在更低的温度、压力条件下合成出高质量的板柱状绿柱石晶体.     

晶体对热辐射的吸收对晶体生长的影响

本文综述了晶体对熔体热辐射吸收对晶体生长的影响,包括对热腔热耗散的影响;对晶体生长温度时间特性的影响;对液流形态和固液界面形状的影响;对晶体界面反转的影响;对晶体中温度分布和应力分布的影响.     

Calcium Oxalate Monohydrate Crystal Growth

The growth rate of calcium oxalate monohydrate seed representing aggregates of highly irregular crystals from solutions of the stoichiometric composition with I = 100 mol m⁻³ in the range of supersaturation Δc = 0.056 to 0.353 mol m⁻³ was measured at 37 °C by the constant composition method. The crystal growth rate decreased during the initial period of experiment, then reached a value constant over a considerable time and later increased again. The initial decrease of the growth rate resulted from crystal perfection whereas the later increase was caused by formation of new crystals by secondary nucleation. The supersaturation dependence of the kinetic growth rate satisfied the power law with the growth order equal to 2 and 4 at supersaturations lower and higher than about Δc = 0.150 mol m⁻³, respectively.     

Bas晶体生长研究进展

立方砷化硼(BAs)为间接带隙、闪锌矿结构的Ⅲ-Ⅴ族化合物半导体材料.理论分析预测BAs具有仅次于金刚石的超高热导率,在电子器件散热领域表现出广阔应用前景,成为当前的研究热点.近年来立方BAs单晶材料的制备取得突破性进展,采用化学气相传输法(CVT)合成了毫米尺寸的高质量单晶,室温下热导率高达1300 W·m-1·K-...     

AlN单晶生长行为研究

本文采用物理气相传输法对不同衬底温度和温差下制备的氮化铝(AlN)晶体形貌进行研究,研究结果表明AlN晶体生长受到AlN晶面表面能、Al基元平均动能和AlN晶体表面极性的共同影响。当温差为60℃时, AlN晶体(0001)面生长速率小于(10-10)面,AlN以带状形式生长。将该工艺应用于AlN同质生长中,研究结果表明:温差为60℃时AlN晶体(0001)面呈现畴生长模式,该晶体质量最差;温差为35℃时AlN晶体(0001)面呈现台阶流生长模式,该晶体质量最优;温差为20℃时AlN晶体(0001)面呈现台阶簇生长模式,该晶体容易开裂。通过工艺优化最终获得了直径为40 mm AlN单晶衬底,完全满足器件制备需求。     

Yb:FAP晶体生长

采用中频感应提拉法生长了Yb：FAP晶体。对晶体生长中影响晶体质量的因素特别是原料的处理、CaF2的挥发等进行了研究和讨论。运用ICP-AES测定Yb^3＋离子在Yb：FAP晶体中的分凝系数。对Yb：FAP晶体进行了高分辨X射线的四圆衍射实验,结果表明晶体具有比较高的晶格完整性。     

氧化锌晶体生长基元模拟

本文利用Hyperchem分子模拟软件对氧化锌晶体生长基元Zn(OH)42-进行了系统的模拟.通过模拟分析生长基元的结合方式,提出了生长基元的结合规律.结果表明:Zn原子数(生长基元)与共用O原子数(O桥)的比例越大所形成的络合物越稳定;当分子中Zn原子和共用O原子比例一定时,羟基数目越少则越稳定.并且通过计算机模拟生长基元直线状结合情况解释了单晶ZnO纳米线状或纳米棒状的结构很难在实验中获得的原因.     

Monte Carlo Simulation of Crystal Growth

A simple Monte Carlo simulation has been used for the study of crystal growth from solutions. The effect of concentration of the solution, its supersaturation, agitation and presence of admixtures has been investigated. The results of simulation qualitatively correspond to the phenomenon observed experimentally.     

磺基水杨酸锶分光晶体生长的研究

本文采用液相法合成了高纯度磺基水杨酸锶(简称SSS)多晶粉末原料,并采用热分析、红外光谱和XRD分析对多晶粉末原料进行表征。以水为溶剂分别在不同pH值下(pH=2.50、1.50和0.60)进行了SSS结晶习性实验。结果表明,在水溶液中当pH=0.60时SSS结晶性最好,实验还测定了SSS晶体在不同pH值溶液中的溶解度曲线,并进行了过饱和溶液成核机理的研究。研究结果表明,当生长溶液pH为0.60时,控制单晶生长温度在40～50℃区间,采用水溶液降温法可生长出63 mm×25 mm×3 mm的透明单晶。     

碲铟汞晶体的生长研究

以高纯Hg、In、Te单质为原料,在摇摆合料炉中成功地合成了HgInTe多晶原料,并且利用该多晶原料,在特殊设计的坩埚中,成功地生长了HgInTe单晶体.X射线衍射分析证明,所生长的HgInTe晶体为缺陷闪锌矿结构,晶格常数a=0.6293nm,是一种高质量的完整单晶体.     

Study of Mercurous Chloride Crystal Growth

In this work we deal with the mercurous chloride (Hg₂Cl₂) or calomel crystal growth in vapour phase by flux forced method, taking into account the total dissociation of calomel in mercury and mercuric chloride. The concentrations of mercury and mercuric chloride along the growth ampoule depend on the matter transport model from the source to sink. We use a molecular diffusion model of mercury and mercuric chloride through an immobile inert gas. The attempts of growth showed the key role of the concentrations of mercury and mercuric chloride as well as their ratio at the maximum of supersaturation.     

晶体生长界面相研究

在分析前人的晶体生长理论时,作者认为晶体生长过程中可能存在界面相;在分析各种晶体生长现象后认为,晶体生长过程中界面相是存在的,并起着十分重要的作用;通过分析研究,将晶体生长过程中的界面相划分为3个有机的组成部分：界面层、吸附层和过渡层;并进一步论述了界面层、吸附层和过渡层在晶体生长过程中的地位与作用;在此基础上提出了界面相模型。     

高抗灰迹KTP晶体生长与性能研究

采用顶部熔盐籽晶法生长了具有高抗灰迹性能的KTiOPO4(HGTR-KTP)晶体,并对其透过光谱、光学均匀性、相位匹配角、抗激光损伤阈值等性能进行了表征和测试,与普通KTP晶体的对比和大功率激光实验表明该晶体具有高的抗灰迹性能。     

KDP晶体缺陷对生长应力分布的影响

本文采用有限元法分析了不同尺寸、形状的晶体缺陷对大口径KDP晶体生长应力分布的影响.结果表明,晶体中的缺陷导致了晶体内部应力集中,且应力集中程度与缺陷尺寸、晶体生长尺寸呈反向变化,而最大主应力与缺陷尺寸、晶体生长尺寸呈正向变化.当缺陷含有棱边或尖角时,应力集中程度和最大主应力值都明显增加.由于KDP晶体易脆性开裂,随着最大主应力值的增大,开裂机率也增大.     

Crystal Growth from Silica Gels and Single Crystal Structure of Bariumchromate

Rhombic single crystals of bariumchromate were grown in silica gels up to 1.5 mm in size. The influence of the initial pH-value of the gel and the kind and concentration of reactants are studied. The crystal structure has been determined. The compound crystallizes in space group Pnma, with cell dimensions a = 9.113(4) Å, b = 5.528(3) Å, c = 7.336(4) Å and Z = 4. The structure was refined to R = 0.062 on the basis of 364 reflections. Every barium atome, centered in a distorted archimedian antiprism, is coordinated to 8 oxygen atoms each belonging to a chromate tetrahedron. Interatomic distances and bond angles were calculated.     

不同籽晶对多晶硅晶体生长的影响

通过在坩埚底部铺设籽晶来控制形核的同步性,获得均一等大的硅晶粒,实验采用铺设硅粉、颗粒料、碎硅片三种籽晶来诱导硅晶体生长,结果表明硅粉籽晶生长硅晶体晶粒均匀性最好.采用硅粉籽晶所生产硅锭效率比碎硅片籽晶高0.3;.