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氧化物晶体的坩埚下降法生长 总被引:4,自引:2,他引:4
本文评述了氧化物晶体坩埚下降法生长的一些研究进展,重点介绍我们研究所在压电晶体、非线性光学晶体、弛豫铁电晶体、闪烁晶体、声光晶体、光折变晶体等方面的研究工作.从技术创新的角度探讨了氧化物晶体坩埚下降法生长工艺的新发展,如连续供料坩埚下降法、熔剂坩埚下降法等. 相似文献
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以高纯硼酸、碳酸锂和碳酸铯为原料,摩尔比硼酸:碳酸锂:碳酸铯=11:1:1,采用顶部籽晶法,生长出尺寸为65 mm×22 mm×12 mm CsLiB6O10(CLBO)单晶,探讨了影响CLBO晶体生长的因素.对生长出的CLBO晶体的相关光学性质进行了研究.CLBO晶体的光学均匀性为3.6×10-5/cm,透过光谱表明该晶体的透光范围为185 nm到2790 nm,其紫外吸收边低于185 nm;用Maker干涉条纹测定了CLBO晶体的非线性光学系数为:d36(CLBO)=1.8d36(KDP). 相似文献
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采用导模法生长出六片片状蓝宝石晶体,单片尺寸为350 mm×80 mm×2 mm.通过CGSim模拟软件模拟计算和实验验证,确定了合适的生长温场为横向温梯2.9~4.6 K/mm,生长速度控制在5~10 mm/h之间.对晶体进行双晶摇摆曲线测试,峰强度很高且对称性良好,摇摆曲线的半高宽FWHM=16.946″,证明晶体的结晶完整性很高.采用化学腐蚀法对六片晶体进行位错密度的检测,计算出晶体的位错密度都在103量级,中间晶体位错密度小于两边晶体的位错密度.测试了六片晶体的弯曲强度,最高强度达1583 MPa,中间晶体强度大于两边. 相似文献
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通过选择合适的原料配比(Li2O 48.6mol;,Nb2O5 51.4mol;),控制固液界面处的温度梯度为20~40℃/cm,晶体生长速度为0.6~1.5mm/h,采用密闭条件下的坩埚下降法工艺成功地生长出了具有良好光学均匀性的完整LiNbO3单晶.用X射线粉末衍射表征获得的LiNbO3晶相,讨论了若干工艺条件对晶体组分与质量的影响.测定了未密闭条件下生长的LiNbO3晶体不同部位样品的紫外可见光谱,发现其吸收边沿生长方向发生红移,并讨论了产生此现象的原因. 相似文献
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作为第二代半导体材料,GaAs晶体自60年前被发现以来已广泛应用于激光、通讯和显示等领域,并发展出液封提拉法、水平布里奇曼法、垂直梯度凝固法等多种生长工艺.本文总结了GaAs晶体的最新研究进展,探讨了各种生长方法的特点及其应用,重点报道了GaAs晶体坩埚下降法生长的研究成果.坩埚下降法具有一炉多产、易操作、低成本等优点,已成为GaAs晶体产业化的重要途径.掺杂不仅能调节GaAs晶体的性能,还会对晶体生长产生重要影响.本文还给出了Bi、Si、Zn等掺杂GaAs晶体生长结果,探讨了它们的性能、缺陷以及在不同领域里的应用. 相似文献
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C. Gross W. Assmus A. Muiznieks G. Raming A. Mühlbauer C. Stenzel 《Crystal Research and Technology》1999,34(3):319-328
An analytical model for a Skull melting set-up is presented, which describes the power absorption in the melt and the losses in the inductor coil and the cold crucible. A strong dependence of the relative size of these quantities on the applied frequency has been found. Above a characteristic frequency, where the skin depth equals about one half of the melt radius, only a small percentage of the overall power (typically 10% for oxide melts) is lost in the copper coil and the crucible. Below this frequency, the relative part of these losses increases considerably and can prevent a successful Skull melting experiment. Analytical results are in good agreement with experimental (calorimetric) measurements of the power consumption in a typical Skull run (cubic stabilized zirconia), and with corresponding numerical simulations of the Skull process. The thermal conductivity of the Skull crust was estimated from experimental data. 相似文献
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A. Muiznieks G. Raming A. Mühlbauer C. Gross W. Assmus C. Stenzel 《Crystal Research and Technology》1999,34(3):329-338
A mathematical model for the numerical calculation of the shape of the molten zone during high frequency (HF) inductive Skull melting of ceramic materials in the cold crucible is presented. The mutual interaction between the molten zone and the HF electromagnetic field of the inductor is considered by an axisymmetric model because of the good electromagnetic transparency of the slitted crucible wall (see part I). By means of the developed corresponding Finite-Element program package the shape of the molten zone and corresponding power consumption of the system are calculated. The dependence of the shape of the molten zone on system parameters is analysed numerically and compared with experimental data. Additionally, some further investigations on stability of the molten zone are performed. 相似文献
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本文在考虑硅料的堆积孔隙率和熔化变形等因素的基础上,建立了基于多孔介质的堆积硅料简化模型,对光伏太阳能用准单晶硅铸锭系统的硅料熔化过程进行了数值模拟,研究了不同侧/顶加热器功率比、堆积孔隙率以及加热器总功率对籽晶熔化的影响。研究结果表明:硅料的熔化时间和籽晶的熔化比例取决于侧/顶加热器功率比,降低侧/顶加热器功率比和堆积孔隙率有助于籽晶的有效保留,但会导致籽晶的熔化界面形状发生变化,使杂质在籽晶熔化界面形状为“凹”的区域内聚集,进而影响后续晶体生长的质量;当加热器的总功率低于临界值之后,籽晶的熔化界面形状会在靠近坩埚壁面的边缘区域发生变化,导致不均匀成核的发生,不利于准单晶硅铸锭的生产。在实际工况条件下,可以根据由侧/顶加热器功率比、堆积孔隙率、加热器总功率、籽晶的熔化比例和状态绘制的等值线图对工艺参数进行合理配置。 相似文献
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为研究钙稳定氧化锆质材料的高温电性能,以CaO为稳定剂,分别按照4mol;、8mol;和12mol;的掺杂量,与化学法制备的高纯氧化锆细粉混合,于模压法成型后,经1710℃×2h烧成制得试样.采用XRD和SEM分别对试样相组成和显微结构进行了分析,测定了不同试样室温到1350℃的电导率.实验结果表明:随着CaO掺杂量的增加,试样中立方相氧化锆含量增加,单斜相含量明显减少;试样的电导率随稳定剂掺杂总量的增加呈上升趋势,且随着测试温度的升高而增大;不同相组成使氧化锆材料在高低温区电导率存在着差异,其中立方相含量的增加有助于电导率的提高. 相似文献
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正向化学沉淀法制备纳米ZrO2及其表征 总被引:2,自引:0,他引:2
以ZrOCl2·8H2O和NH3·H2O为原料,采用正向化学沉淀法制得了纳米ZrO2,并系统地研究了不同反应条件如:反应物初始浓度、反应温度、沉淀剂加入方式、溶液pH值、煅烧温度和时间等对粒径大小、均匀度的影响,采用Malvem粒度分布仪、扫描电子显微镜、红外光谱仪和X射线衍射仪等对产品进行了表征,并得出结论:正向化学沉淀法制备纳米氧化锆,所得粒子粒度较小、均匀性好,而且反应速度较快、操作简便. 相似文献
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Teruo Kitamura Akio Mukoh Masato Isogai Takashi Inukai Kenji Furukawa Kanetsugu Terashima 《Molecular Crystals and Liquid Crystals》2013,570(2-4):167-173
A series of chiral benzylidene-aniline compounds, 4-alkoxybenzylidene 4′-(2-methylbutyloxycarbonyl)anilines, have been synthesized and their mesomorphic properties are examined. They showed a monotropic chiral smectic C phase in conjunction with enantiotropic smectic A phase, and their chiral smectic C—smectic A phase transition temperatures are around room temperatures. Their spontaneous polarization values are moderately higher than those of DOBAMBC “4-decyloxybenzylidene 4′-amino-(2-methylbutyl)cinnamate”. 相似文献
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Lunyong Zhang Hongbo Zuo Fuyang Cao Dawei Xing Jianfei Sun Xiaohong Wang Jiecai Han 《Crystal Research and Technology》2012,47(2):175-182
A mathematical model has been proposed to design the process for growing a shaped crystals by Kyropoulos method or SAPMAC method. Crystal shape evolution behaviours under various processes were analysed. The results show that the crystal would go through a transitory shoulder‐expanding stage after which the crystal diameter rapidly decreases under a constant pulling rate and a constant heater temperature. Reducing pulling rate and heater temperature could depress the decrease of crystal diameter after the shoulder‐expanding stage so that enhance the length of crystal. However, the crystal diameter is more sensitive to pulling rate than to heater temperature, and an equal‐diameter crystal can not be grown in non‐undercooled melt by soley reducing the heater temperature. That means that adjusting the pulling rate is the most effective and convenient approach for controlling crystal diameter evolution and simultaneously decreasing both the pulling rate and the heater temperature is the optimal process for growing an equal‐diameter crystal. Moreover, a numerical approach for quantifactional designing crystal shape and corresponding growth processes was proposed according to the model, an example of crystal shape design was given out. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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锰锌铁氧体纳米粉体的烧结过程及其性能测试分析 总被引:2,自引:0,他引:2
本文研究了锰锌铁氧体纳米粉体的烧结过程及晶粒生长规律,采用传统成型工艺和分段烧结方式,研究坯体的致密化和晶粒生长情况.分别采用阿基米德法、扫描电镜(SEM)和X射线衍射仪(XRD)对烧结体的密度、微观结构和相组成进行测试分析.烧结体的磁性能用振动样品磁强计(VSM)来测定.另外,根据[311]衍射峰的半高宽,利用Scherrer公式计算烧结体晶粒的大小.结果表明,在900℃烧结时,烧结体的密度达到了功率锰锌铁氧体材料所需的最佳密度,此时晶粒生长较好,得出900℃为Mn-Zn铁氧体纳米粉体的最佳烧结温度,此时烧结体的密度为4.8245g/cm3. 相似文献