SiC衬底上生长的GaN外延层的高分辨X射线衍射分析

通过高分辨X射线衍射(HRXRD)技术,对金属有机化合物气相外延(MOCVD)生长的GaN外延膜及SiC衬底的相对取向,晶格常数和应力情况,位错密度等进行了分析.分析表明,GaN和SiC具有一致的a轴取向,GaN外延层弛豫度超过90;,GaN外延层的晶格常数与体块材料相近,在GaN中存在压应力,SiC衬底和GaN外延层中的位错密度分别为107和108量级.     

宏观内应力掠入射衍射分析中X射线折射作用引入的误差

宏观内应力X射线掠入射衍射分析中,X射线折射作用引入的衍射角测定误差必然对分析产生影响.本文基于数值方法计算了Euler角定位及Hauk角定位的X射线掠入射衍射分析中因X射线折射作用引入的衍射角测定误差及其在几种宏观内应力测试方法中引入的应变测定误差.在一定角度范围内采用侧倾法可避免X射线折射作用引入的应变测定误差,而采用侧倾法及固定X射线有效穿透深度的Ψ-Ω法测试时必须对测定结果进行数据修正.     

X射线粉末衍射解析三元化合物ErCo0.67Ga1.33晶体结构

采用水冷铜舟真空电弧炉在高纯氩气保护下熔制ErCo0.67Ga1.33合金样品,并进行高温长时间真空退火,获得单相ErCo0.67Ga1.33三元化合物,然后利用X射线粉末衍射技术和Rietveld结构精修法解析化合物ErCo0.67Ga1.33晶体结构,其晶体结构数据如下:a=0.43084(1)nm,b=0.68911(2)nm,c=0.75135(2)nm,Z=4,密度Dcalc=8.937 g/cm3,正交结构类型,空间群Imma(No.74),与CeCu2同构.Rietveld结构修正的结果为:峰形因子Rp=9.67;,权重因子Rwp=12.66;.计算德拜温度ΘD=392.7 K.     

醇热合成ZrO2粉末的X射线衍射及拉曼散射特征

以氧氯化锆和氨水为反应原料,在醇热条件下进行了合成纳米ZrO2的实验.对甲醇、乙醇、正丁醇介质中合成的ZrO2进行了X射线衍射和激光拉曼散射表征.结果表明,在150℃,填充度为75;的醇热实验条件下合成了晶粒度为纳米级的氧化锆粉体;粉体为由四方相ZrO2和单斜相ZrO2组成的混合物;甲醇、乙醇、正丁醇介质中合成的ZrO2的拉曼活性依次增强;正丁醇中反应时间延长,合成的ZrO2的拉曼活性增强.     

高分辨X射线衍射术对NdP5O14晶体的自发应变及铁弹畴结构的研究

利用助溶剂法,已经生长出15mm×25mm×60mm的大尺寸NdP5O14(NPP)晶体.用高分辨X射线衍射术对自发应变及铁弹畴结构进行了研究.对几个不同的反射,可在其摇摆曲线上观测到由基体畴和铁弹畴之间的取向差导致的反射峰的分离.通过反射峰分离的特点,可以确定铁弹畴结构.NPP晶体中大多数铁弹畴为a型畴,b型畴只出现在严重形变的区域. 基于NdP5O14晶体畴结构,我们分别计算了802,402和204反射的峰分离量.实验测量结果符合计算结果.另外,通过测量基体畴和铁弹畴的800反射的峰分离量我们确定了NdP5O14的自发应变是0.0082.通过结构和对称性分析,我们对这种晶体的畴结构进行了详细讨论.     

高分辨X射线衍射法研究碳化硅单晶片中的多型结构

我们采用高分辨X射线衍射法对SiC单晶片中的多型结构进行了研究,研究发现在以4H-SiC为籽晶的晶体生长过程中,4H-SiC、6H-SiC、15R-SiC出现两相共存或三相共存现象.在单相、两相或三相共存区,X射线摇摆曲线具有明显不同的特征.根据多型结构,可以对摇摆曲线中的衍射峰进行鉴定.     

软X射线分光晶体研究进展

本文介绍了软X射线分光晶体的应用及研究重要性,以及从X射线分光晶体的组成、结构与性能的关系介绍了分光晶体的分类,并对近代晶体生长的方法作了简要的描述。     

RF-PECVD制备微晶硅薄膜的X射线衍射研究

采用X射线衍射(XRD)技术连续扫描法和薄膜衍射法对RF-PECVD制备的微晶硅薄膜结构进行了研究.改变硅烷浓度和反应功率,控制薄膜的生长速率,已达到制备不同材料的目的.根据硅基薄膜的电学特性和XRD测试,随着反应功率的增加,硅基薄膜的生长速率不断提高,微晶硅薄膜的晶化程度不断增大.     

β-Ga2O3体单晶X射线光电子能谱分析

通过对导模法制备的非故意掺杂、Si掺杂β-Ga2 O3晶体和Si掺杂后退火处理的β-Ga2 O3晶体进行了X射线光电子能谱分析(XPS),对比分析不同样品的Ga3d、Ga2p、O1s特征峰位和峰强度变化,并结合文献报道中β-Ga2O3薄膜及单晶材料的报道结果,进一步确认β-Ga2 O3体单晶特征峰峰值.同时,通过对各峰强度的变化进行对比分析,对次峰产生的原因进行推测,获得Si掺杂及退火对晶体表面及晶体内部个特征峰的变化规律.     

Diffraction reflection of a focused X-ray wave by a multilayer crystal

The Bragg diffraction of a narrow X-ray beam in a multilayer crystal is studied in the reflection geometry. It is shown by computer simulation of the experiment that strong integrated kinematic reflection occurs at any boundary of a multilayer crystal at the point of intersection of a narrow beam with the boundary. In contrast to the dynamic diffraction of a plane wave, attenuation of a narrow incident beam due to the reflection is small in comparison with the conventional absorption. As an example of a multilayer crystal, a Fabry-Perot interferometer is considered, which consists of two 70-μm-thick crystal Si layers separated by a 100-μm-thick air layer. The 12 4 0 reflection is studied at a photon energy of 15 keV. Three methods of formation of a narrow beam are considered: wavefront limitation by a slit, focusing with a parabolic lens, and focusing with a zone plate. It is shown that, for a local analysis of the thickness of layers and scattering parameters, the method of parabolic lens focusing has some advantages in comparison with the other methods.     

Stereometrical X-ray Interferometric Diffraction Topography of Crystal Imperfection

A method for X-ray interferometric investigation of the deformation field of crystal imperfections by means of double and triple interferometers is proposed. It is shown experimentally that by means of double and triple interferometers it is possible to detect segregation lines, displacement lines, and the Moiré patterns of different type imperfections as well.     

大面积自支撑CVD金刚石厚膜的应力研究

在HFCVD系统中制备了直径为φ100 mm的自支撑CVD金刚石厚膜,利用XRD研究了自支撑CVD金刚石厚膜的应力.结果显示制备的大面积自支撑CVD金刚石厚膜处于较低的应力水平,应力分布较均匀,生长面应力状态为压应力,成核面应力状态为张应力.     

Melt-Growth of Single Crystals of Cadmium Iodide and Study of Their Polytypsim by X-ray Diffraction

Single crystals of cadmium iodide have been grown from melt using Bridgman-Stockbarger system and their polytypism studied by X-ray diffraction. The initially grown crystals were found to stick to the walls of the ampoule and had black specks of impurity suspended in them. A systematic study has been carried out to determine the effect of degree of vacuum, material of the ampoule and quality of raw material on crystal growth. It has been concluded and later verified using zone-refined material that the observed sticking essentially stems from the presence of impurities in the raw material. From X-ray diffraction it is found that all crystals belong to the most common polytype 4H alone.     

Single Crystal X-ray Diffraction Study of a Pure Natrolite Sample

The crystal structure of a pure natrolite sample, Na₂(Al₂Si₃O₁₀)·2H₂O, coming from Asheken, Ethiopia, has been analysed by single crystal X-ray diffraction. It crystallizes within the orthorhombic space group Fdd2, with the following cell constants: a = 18.2930(2) Å; b = 18.6430(5) Å; c = 6.5860(5) Å; V = 2246.07(18) Å³. The three-dimensional framework of this hydrated aluminosilicate zeolite is made up by chains of corner-sharing SiO₄ and AlO₄ tetrahedra down c; the chains are held together by sharing the external vertices of tetrahedra; water molecules and Na⁺ extra-framework cations fill up the resulting cavities, the latter forming irregular NaO₆ octahedra. Hydrogen bonds complete the array.     

X-ray Diffraction and DFT Studies of 2-Methoxy-5-phenylaniline

Abstract 2-Methoxy-5-phenylaniline, a promissor monomer for PANI studies, has been characterized by single-crystal X-ray diffraction at two temperatures: orthorhombic, space group P2₁2₁2₁, Z = 12 with a = 5.9900(2) ?, b = 20.4873(6) ?, c = 26.3727(8) ? and R = 0.0868 for 293(2) K and a = 5.8337(9) ?, b = 20.4428(31) ?, c = 26.0773(40) ? and R = 0.0669 for 120(2) K. There are three independent molecules in the unit cell. One of them is approximately planar, the other two have the phenyl rings rotated. At room temperature the two latter molecules are joined in dimers through H-bonds and at low temperature the same molecules are joined in columns that run along the a-axis. Index Abstract X-ray Diffraction and DFT Studies of 2-Methoxy-5-phenylaniline Ana T. Marques, Joana A. Silva, Manuela Ramos Silva, Ana Matos Beja, Licinia L. G. Justino, Abilio J. F. N. Sobral 2-Methoxy-5-phenylaniline, a promissor monomer for PANI studies, has been characterized by single-crystal X-ray diffraction at 293(2) K and 120(2) K. The three independent molecules in the unit cell show different conformations and establish distinct intermolecular H-bonds.