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PIMNT单晶是近年来最新发现的弛豫铁电晶体材料,该三元固溶体单晶具有比较理想的压电、铁电和介电性能,本文报道了大尺寸PIMNT单晶的熔体坩埚下降法生长的实验研究结果。采用固相合成钙钛矿相多晶料,采用垂直坩埚下降法成功生长出最大直径为3英寸的PIMNT单晶;从所生长单晶原胚的三方相区段切割加工出(001)取向晶片,就(001)晶片的介电、压电及铁电性能进行了测试表征,表明其材料性能能够满足相关超声换能器件制作的实用需求。本论文还着重讨论了PIMNT单晶生长所涉及的系列关键技术问题,如富铅熔体对铂金坩埚的侵蚀、晶体原胚的单晶性表征、晶体生长过程的组分偏析与单晶原胚的性能分布等。 相似文献
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本文介绍了最近几年在SiC单晶生长和晶片加工技术产业化进程中的系列进展。研究出SiC单晶生长的扩径技术,4英寸SiC晶体单晶直径达105 mm。晶体质量逐步提高,至2011年,大部分晶片微管密度小于1个/cm2,反映晶体结晶质量的X射线摇摆曲线半高宽小于20″;生长的导电型SiC晶体电阻率小于0.02Ω.cm,半绝缘型SiC晶体电阻率大于108Ω.cm,电阻率分布均匀性良好。研究出即开即用SiC晶片批量加工技术,晶片表面粗糙度低于0.2 nm,翘曲度和总厚度变化满足工业化批量生产要求。与此同时,在基础物性研究方面也取得了系列研究成果。首次在实验上给出了直接证据证明SiC晶体中的双空位能够诱导出磁性,并从理论上予以证明。利用多种方法在SiC衬底上成功制备出大面积、高质量、性能优异的石墨烯。 相似文献
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以In2O3、Nb2O5、4MgCO3·Mg(OH)2·4H2O、TiO2、PbO为初始试剂,先合成出前体化合物MgNb2O6和InNbO4;按照0.25Pb( In1/2 Nb1/2) O3-0.44Pb( Mg1/2 Nbv3)O3-0.31PbTiO3的组分比例,添加1.5 mol%过量PbO,通过高温固相反应合成出PIMNT多晶料.X射线粉末衍射、差热/热重分析表明,PIMNT多晶系钙钛矿结构的固溶体化合物.采用本实验合成PIMNT多晶料锭,通过坩埚下降法成功生长出25mm直径的PIMNT单晶,证实采用预先合成多晶料有助于钙钛矿相PIMNT单晶的稳定生长. 相似文献
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蓝宝石晶体的生长方向研究 总被引:4,自引:3,他引:1
本实验采用提拉法,在中频感应加热单晶炉内,进行了不同生长方向蓝宝石晶体的生长工作,分别取[11-20]和[0001]生长的晶体c面(0001)的晶片.通过应力仪、显微观测和X射线衍射等方式对晶片的位错密度等微观缺陷以及晶体结构进行了检测.实验表明:不同的生长方向生长得到的蓝宝石晶体的质量存在一定的差别,一般情况下,[11-20]方向生长的蓝宝石晶体质量优于[0001]方向生长的晶体. 相似文献
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通过高温固相反应或湿化学法合成ZnWO4多晶料,采用垂直坩埚下降法生长出φ25 mm× 60 mm的透明完整钨酸锌单晶.应用X射线粉末衍射分析证实了所制备钨酸锌多晶与单晶的结晶物相,测试了钨酸锌单晶的紫外可见透射光谱、光致发射光谱和X射线激发发射光谱,讨论了此闪烁单晶的氧气氛退火效应.结果表明,该单晶的透射光谱在400~800 nm波长区域呈现典型光学透过性,其吸收截止边位于380 nm左右,在紫外激发光或X射线激发作用下,此单晶具有峰值波长位于470 nm的荧光发射;此单晶经980℃温度下的氧气氛退火处理,其晶体着色有所变浅而光学透过性得以明显改善. 相似文献
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Xian Wang Haiwu Zhang Di Lin Sheng Wang Xiangyong Zhao Jianwei Chen Hao Deng Xiaobing Li Haiqing Xu Haosu Luo 《Crystal Research and Technology》2014,49(2-3):122-128
Compositional segregation usually has negative effects on the growth of solid solution ferroelectric single crystals of Pb(In1/2Nb1/2)O3‐Pb(Mg1/3Nb2/3)O3‐PbTiO3 (abbr. PIN‐PMN‐PT or PIMNT). A modified Bridgman method was adopted in this work to control the segregation and improve the compositional homogeneity significantly. The characteristic of this work is to use multiround growths and gradient composition raw materials in order to keep the PbTiO3 concentration constant during the crystal growth. As an example, the two‐round growth of ternary PIN‐PMN‐PT single crystal is conducted in the same Pt crucible with gradient raw materials, where the first‐round boule was used as the seed crystal for the second‐round growth. Our results show that the as‐grown (Ф80 mm × 270 mm) PIN‐PMN‐PT crystals exhibit higher phase transition temperatures (Tc∼180 °C, Tr/t∼110 °C) and larger coercive field (Ec∼5–5.5 kV/cm), which are much better than the performances of Pb(Mg1/3Nb2/3)O3‐PbTiO3 crystals, and similar dielectric and piezoelectric performances (ε∼5000, tanδ∼1.25%, d33∼1500 pC/N, kt∼60%). And about 85 percent of the crystal boule grown by the two‐round growth technique could maintain its compositions around the morphotropic phase boundary. 相似文献
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Cuprous iodide crystals have been grown with decomplexation method in silica gel. Various crystal morphologies, such as polycrystalline aggregate, skeletal, dendrite, hopper crystals and regular tetrahedron crystals, were observed in different growth regions with an optical microscope. Their surfaces were photographed using a binocular metallographic microscope and the results were explained with the crystal growth mechanism which was determined by supersaturation. These observations support the general hypothesis that the concentration of reactant affects the relative growth rate by controlling the nucleation and diffusion. The mutual influence of the crystals grown in different regions was also discussed. Additionally, the suitable condition for getting regular tetrahedron crystals or large hopper crystals was obtained by changing the concentration of CuI·HI complex in the later period of crystal growth. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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对三联苯是一种常见的有机闪烁剂,通常用作闪烁计数器的发光材料。对三联苯闪烁晶体具有对中子探测效率高以及不易潮解等特性,这使其在实际应用中具有广阔的前景。本文采用坩埚下降法,使用单层安瓿成功生长出φ12 mm×30 mm对三联苯晶体。在生长开始前通过差热分析,确定晶体的生长温度。生长完成后测试了晶体粉末的X射线衍射谱、摇摆曲线、红外光谱、荧光光谱和拉曼光谱。X射线衍射结果表明,生长的晶体为纯对三联苯相。从摇摆曲线结果可以看出,生长晶体质量良好。红外和拉曼分析结果显示,峰位并没有出现明显的偏移,表明晶体中杂质含量较少并未引起晶体分子化学结构的变化。荧光光谱没有杂质峰的出现也说明对三联苯晶体存在较少杂质或晶格缺陷。 相似文献
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Nonlinear optical single crystals of YCOB with good optical quality were grown by the flux technique for the first time. Polycrystalline YCOB samples were synthesized by solid state reaction method. The thermal analysis of the sample was performed with lithium carbonate flux in different weight proportions and the growth temperature was optimised. Single crystals of YCOB with dimensions 3 × 3 × 5 mm3 were obtained by the method of ‘slow‐cooling’. The grown crystals were characterized by XRD, UV‐VIS‐NIR, EDAX, FTIR and etching studies. The powder XRD pattern revealed the formation of YCOB compound. The lattice parameters were identified through single crystal XRD studies. The UV‐VIS‐NIR results showed that the crystal has a sharp cutoff at 220 nm and is nearly 55% transparent over a wide wavelength range enabling applications in the UV region. The EDAX measurement revealed the ‘flux‐free’ crystal formation. The presence of the functional groups belonging to the YCOB crystals was identified by the FTIR results. ‘Hillock‐like’ patterns are observed in the etching studies. The primary emphasis in this study is laid to describe ‘flux technique’ as an alternative method to grow YCOB crystals. The results are presented and discussed. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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KLN, Fe:KLN, Mn:KLN and Cu:KLN crystals were grown by Czochraski method. The structure of crystal was measured by X‐ray diffraction technique. The results indicated that the doped crystals kept the same structural characteristics as the pure KLN crystal, but the lattice constants of Fe:KLN and Mn:KLN crystals became smaller than that of pure KLN crystal, and that values of Cu:KLN crystal became larger than that of pure KLN crystal. This indicated that Fe and Mn cations replaced Nb cation, and Cu cation replace K cation after they entered into the lattice of KLN crystal. The result of ultraviolet‐visible absorption spectra was identified with that of X‐ray diffraction analysis. 相似文献