低位错ZnSe单晶的生长

采用化学气相输运法(CVT)在适合的温度和I2含量的条件下,生长出了25mm×3mm的ZnSe单晶,位错密度为6.5×103个/cm2.对ZnSe单晶进行光学性能分析,在10.6μm处的透过率超过70;,在10.6μm处的吸收系数为7.72×10-4/cm.     

ZnSe单晶生长及性能研究

采用物理气相输运法对ZnSe(4N)多晶原料在850℃±10℃进行提纯,再用高压坩埚下降法在1530℃、氩气保护气氛下生长出高质量ZnSe单晶体.研究了提纯过程温度的选择以及氧含量和压力对于晶体生长的影响.对生长出的单晶体进行均匀性测试表明ZnSe单晶完整性和均匀性良好.对ZnSe单晶进行光学性能测试分析表明ZnSe单晶的折射率高,吸收系数低,红外透过率大于70;.     

单质直接气相生长ZnMgSe单晶

采用高纯Zn、Mg、Se2单质为原料,以NH4Cl作为反应输运剂,用化学气相输运(CVT)的方法一步成功生长出ZnMgSe单晶。通过XRD、RO-XRD、EDS、紫外可见分光光度计和光致发光(PL)技术研究了ZnMgSe晶体的结构、成份以及光学特性。结果表明:ZnMgSe单晶具有良好的结晶性能,在400～800 nm范围内透过率达到40%～50%,在2.2～2.6 eV范围内存在与深能级电子复合相关的发光带。研究证明由Zn、Mg、Se2单质在输运剂NH4Cl辅助下一步直接合成ZnMgSe单晶是可行的。     

CVT一步生长的ZnSe单晶的光电特性研究

本文采用化学气相输运(CVT)法,由Zn(5N)和Se(5N)一步直接生长了片状ZnSe单晶,并对其结构特性和光电性能进行分析。研究表明,生长出的ZnSe单晶仅显露(111)面,红外透过率约为40%～42%,具有较高的结晶质量。该ZnSe单晶可与In电极形成良好的欧姆接触,其体电阻率约为7.3×109Ω.cm。     

Zn-Mg-Se-I2系统生长ZnMgSe单晶及其特征

以高纯的Zn、Mg以及Se2单质为生长原料,加入高纯的碘单质作为反应输运剂,采用化学气相输运(CVT)方法成功制备了ZnMgSe单晶,并且分别采用X射线衍射、双晶衍射、紫外可见分光光度计、红外光谱仪以及光致发光(PL)技术研究了晶体的结构、结晶质量以及光学性质.结果表明,制备的单晶结晶性能良好,在500 ～ 1500 nm波长范围内的透过率接近50;,在400 ～ 4000 cm-1波长范围内的透过率达到42;,在2.0～2.6 eV范围内有三个明显的空位与杂质发光带.以Zn、Mg及Se2单质为生长原料,在输运剂I2的帮助下可以实现ZnMgSe单晶的生长.     

ZnSe和Cr∶ ZnSe单晶的温梯法制备及光学性能研究

采用温度梯度法(TGT)生长了直径为32 mm大尺寸ZnSe晶体.对生长出的ZnSe单晶进行了光学性能分析.采用磁控溅射方法在ZnSe晶体上镀铬膜,通过热扩散方法成功制备出中红外Cr∶ ZnSe激光晶体,并研究了Cr∶ZnSe晶体的光谱性能.吸收光谱测试观察到了Cr2+(3d4)取代四面体配位Zn2的5T2→5E能级的跃迁在1800nm的吸收带.77 K低温的光致发光光谱表明Cr∶ ZnSe晶体具有中心波长位于2.2 μm的宽谱带发射特征.     

ZnSe红外窗口材料的性能及其制备

ZnSe是一种优秀的红外窗口材料,得到广泛的关注.在本文叙述了ZnSe红外窗口材料的光学特性和力学特性,以及详细地描述ZnSe体单晶熔体法、气相法、溶液法和固相再结晶制备技术及其影响因素.     

水热法生长纯相磷酸铁锂单晶

以碳包覆磷酸铁锂为前驱体,磷酸二氢锂为矿化剂,采用水热法制备出纯相磷酸铁锂体单晶,单晶宏观呈类六棱柱形态.晶体由三个主要生长面(010)、(101)、(100)构成.对单晶结构进行分析,获得晶胞结构为D2h16,Pbnm空间群,其中a=1.03217 nm,b=0.60042 nm,c=0.46889 nm,α=β=γ=90°.LiFePO4晶体的拉曼图谱显示的三个强峰分别是949 cm-1,996 cm-1和1068 cm-1,可以作为区分磷酸铁的特征峰.     

铌锌酸铅-钛酸铅单晶的生长及性能

本文系统地研究了(1-x)Pb(Zn1/3 Nb2/3)O3-xPbTiO3(PZN-PT)单晶的光学透过率与结晶取向和组分的关系,发现四方相单晶的透过率明显大于三方相和准同型相界(MPB).[001]方向极化的四方相PZN-12％PT单晶在0.5～5.8μm的波段范围内,未镀增透膜的晶片透过率约为65％;准同型相界处...     

CdSe单晶体的生长及其特性研究

本文报道了用改进的垂直气相法(多级提纯垂直气相法)生长富Cd的CdSe单晶体,并对晶体的性能进行了观测,其电阻率为107Ωcm量级,电子陷阱浓度为108cm-3量级,第一次报道了(110)面的腐蚀形貌。结果表明：采用这种方法制备CdSe单晶,设备简单,易于操作,在提纯和生长过程中不需要转移原料,有利于减少晶体中的杂质含量,降低位错密度,改善晶体的电学性能。多级提纯垂直气相法是一种有前途的CdSe单晶体生长的新方法。     

Growth of Vanadyl Pyrophosphate Single Crystals

The present work communicates about the first successful attempt at growing of sizeable single crystals of vanadyl pyrophosphate (VO)₂P₂O₇ (VOPO) — a low dimensional antiferromagnet. The growth of VOPO is complicated by two features of this compound. The first is a strong sensitivity of the oxydation state of vanadium (and stability of VOPO) to the oxygen content in the growth atmosphere. The second is a tendency of the VOPO-melt to glass formation during the cooling due to its high viscosity. Therefore the growth has to be carried out with a very low growth rate and in an atmosphere with exactly controllable oxygen content. The best results were achieved with a combination of Czochralski and Kyropoulos techniques, i.e. pulling of crystals with simultaneous cooling of the melt. Crystals of VOPO with sizes up to 10 × 5 × 3 mm³ have been grown. The growth from the melt is accompanied by growth from gaseous phase also (sublimation). Since the VOPO phase has a homogeneity range in oxygen content, attention was paid to the composition of the grown crystals. Growth experiments combined with TGA and XRD measurements show, that the oxygen content and thus the oxidation state of vanadium in the crystals can be adjusted accurately.     

Preferred Growth of Antimony Single Crystals

Single Crystals of antimony were grown by the Chalmer's method from the melt. The crystals were grown under different temperature gradients of 92 °C/cm, 75 °C/cm and 52 °C per cm. The growth velocities were varied from 1.5 cm/hr to 9 cm/hr. At low growth velocities antimony exhibits a preferred orientation in the range 1 cm/hr to 6 cm/hr. No effect of temperature gradient is observed. The results are compared with those of bismuth, cadmium and zinc which are contradictory to what has been observed.     

Growth and Characterisation of Potassium Pentaborate Single Crystals

Single crystals of potassium pentaborate were grown by the solution growth method. The grown crystals were characterised by optical transmission spectrum, differential thermal analysis, and thermogravimetric analysis. The coefficient of thermal expansion was also determined and the results discussed.