Growth and Structural Characterization of Znse Single Crystals

1989 ◽  
Vol 152 ◽  
Author(s):  
Elmer E. Anderson ◽  
Hai- Yuin Cheng ◽  
Michael J. Edgell
Keyword(s):  
Single Crystals ◽  
Electron Spectroscopy ◽  
Vapor Transport ◽  
X Ray Diffraction ◽  
Etch Pits ◽  
X Ray ◽  
Etch Pit ◽  
Auger Microscopy ◽  
Transport Method

ABSTRACTSingle crystals of ZnSe have been grown by the physical vapor transport method in sealed quartz ampoules. The largest crystal grown measures 1 cm x 4 mm x 2 mm and required a total growing time of 11 days. Polished wafers cut from the crystals have been etched and examined by optical microscopy, x-ray diffraction, scanning electron microscopy (SEM), Auger electron spectroscopy (AES) and scanning Auger microscopy (SAM). No impurities or unwanted phases were detected, but frequent twinning occurs. Zn-rich {111} faces were identified by SAM. Triangular etch pits are observed on Zn {lll} faces but not on Se faces. Etch pit densities are about 104 per cm2 on slow-cooled samples but are about 100 times greater when cooling is more rapid.

Characterization of Natural and Synthesized FeTiO3 Crystals With RBS/PIXE/XRD

1997 ◽  
Vol 07 (03n04) ◽  
pp. 265-275
Author(s):  
R. Q. Zhang ◽  
S. Yamamoto ◽  
Z. N. Dai ◽  
K. Narumi ◽  
A. Miyashita ◽  
...  
Keyword(s):  
Single Crystals ◽  
Ion Beam ◽  
Pressure Control ◽  
Floating Zone ◽  
X Ray Diffraction ◽  
X Ray ◽  
Beam Analysis ◽  
Ppm Level

Natural FeTiO 3 (illuminate) and synthesized FeTiO 3, single crystals were characterized by Rutherford backscattering spectroscopy combined with channeling technique and particle-induced x-ray emission (RBS-C and PIXE). The results obtained by the ion beam analysis were supplemented by the x-ray diffraction analysis to identify the crystallographic phase. Oriented single crystals of synthesized FeTiO 3 were grown under the pressure control of CO 2 and H 2 mixture gas using a single-crystal floating zone technique. The crystal quality of synthesized FeTiO 3 single crystals could be improved by the thermal treatment but the exact pressure control is needed to avoid the precipitation of Fe 2 O 3 even during the annealing procedure. Natural FeTiO 3 contains several kinds of impurities such as Mn , Mg , Na and Si . The synthesized samples contain Al , Si and Na which are around 100 ppm level as impurities. The PBS-C results of the natural sample imply that Mn impurities occupy the Fe sublattice in FeTiO 3 or in mixed phase between ilmenite and hematite.

Characterization of hydrofluoric acid treated Y–Ba–Cu–O oxides

1989 ◽  
Vol 4 (6) ◽  
pp. 1320-1325 ◽  
Author(s):  
Q. X. Jia ◽  
W. A. Anderson
Keyword(s):  
Hydrofluoric Acid ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Surface Passivation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Zero Resistance ◽  
Reaction With Water ◽  
Scanning Electron

Effects of hydrofluoric acid (HF) treatment on the properties of Y–Ba–Cu–O oxides were investigated. No obvious etching of bulk Y–Ba–Cu–O and no degradation of zero resistance temperature were observed even though the oxides were placed into 49% HF solution for up to 20 h. Surface passivation of Y–Ba–Cu–O due to HF immersion was verified by subsequent immersion of Y–Ba–Cu–O in water. A thin layer of amorphous fluoride formed on the surface of the Y–Ba–Cu–O during HF treatment, which limited further reaction between Y–Ba–Cu–O and HF, and later reaction with water. Thin film Y–Ba–Cu–O was passivated by HF vapors and showed no degradation in Tc-zero after 30 min immersion in water. The properties of the surface layer of Y–Ba–Cu–O oxide after HF treatment are reported from Auger electron spectroscopy, x-ray diffraction, and scanning electron microscopy studies.

Growth and Characterization of bulk GaN by Ga Vapor Transport

2004 ◽  
Vol 831 ◽  
Author(s):  
Phanikumar Konkapaka ◽  
Huaqiang Wu ◽  
Yuri Makarov ◽  
Michael G. Spencer
Keyword(s):  
Growth Rates ◽  
Vapor Transport ◽  
Spiral Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Bulk Gan ◽  
Diffraction Patterns

ABSTRACTBulk GaN crystals of dimensions 8.5 mm × 8.5 mm were grown at growth rates greater than 200μm/hr using Gallium Vapor Transport technique. GaN powder and Ammonia were used as the precursors for growing bulk GaN. Nitrogen is used as the carrier gas to transport the Ga vapor that was obtained from the decomposition of GaN powder. During the process, the source GaN powder was kept at 1155°C and the seed at 1180°C. Using this process, it was possible to achieve growth rates of above 200 microns/hr. The GaN layers thus obtained were characterized using X-Ray diffraction [XRD], scanning electron microscopy [SEM], and atomic force microscopy [AFM]. X-ray diffraction patterns showed that the grown GaN layers are single crystals oriented along c direction. AFM studies indicated that the dominant growth mode was dislocation mediated spiral growth. Electrical and Optical characterization were also performed on these samples. Hall mobility measurements indicated a mobility of 550 cm2/V.s and a carrier concentration of 6.67 × 1018/cm3

Structural Characterization of the Growth Front of 4H-SiC Boules Grown Using the Physical Vapor Transport Growth Method

2018 ◽  
Vol 924 ◽  
pp. 15-18
Author(s):  
Masashi Sonoda ◽  
Kentaro Shioura ◽  
Takahiro Nakano ◽  
Noboru Ohtani ◽  
Masakazu Katsuno ◽  
...  
Keyword(s):  
High Resolution ◽  
Surface Morphology ◽  
Defect Structure ◽  
Growth Front ◽  
Vapor Transport ◽  
Physical Vapor Transport ◽  
X Ray Diffraction ◽  
X Ray ◽  
Growth Method

The defect structure at the growth front of 4H-SiC boules grown using the physical vapor transport (PVT) method has been investigated using high resolution x-ray diffraction and x-ray topography. The crystal parameters such as the c-lattice constant exhibited characteristic variations across the growth front, which appeared to be caused by variation in surface morphology of the as-grown surface of the boules rather than the defect structure underneath the surface. X-ray topography also revealed that basal plane dislocations are hardly nucleated at the growth front during PVT growth of 4H-SiC crystals.

Synthesis and Characterization of Large Single Crystals of Silicon and Germanium Clathrate-II Compounds and a New Tin Compound with Clathrate Layers

2000 ◽  
Vol 626 ◽  
Author(s):  
Svilen Bobev ◽  
Slavi C. Sevov
Keyword(s):  
Alkali Metal ◽  
Single Crystals ◽  
Alkali Metals ◽  
Measured Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mixed Alkali ◽  
Pauli Paramagnetism ◽  
Silicon And Germanium

ABSTRACTWe have synthesized large single crystals of clathrate-II compounds with frameworks of silicon and germanium by employing mixed alkali metal countercations. The combinations of alkali metals are rationally selected in order to fit the different cages of the clathrate-II structure. This approach leads to the following stoichiometric and fully “stuffed” compounds: Cs8Na16Si136, Cs8Na16Ge136, Rb8Na16Si136 and Rb8Na16Ge136. The structures and the corresponding Si-Si and Ge-Ge distances are elucidated and established with high accuracy from extensive single crystal X-ray diffraction work. The compounds are stoichiometric, metallic, and are very stable at a variety of extreme conditions such as heat, concentrated acids, hydrothermal treatment etc. No evidence was found for vacancies in the silicon and germanium networks or partial occupancies of the alkali metal sites. The stoichiometry of these fully “stuffed” clathrates is consistent with the measured temperature independent Pauli paramagnetism, supported also by the conductivity measurements on single crystals and thermopower measurements on pellets. A new compound with novel clathrate-like structure forms when small and large cations are combined with tin. The new materials, A6Na18Sn46 (A = K, Rb, Cs), are made of clathrate layers and the interlayer space filled with Sn4-tetrahedra and alkali-metal cations. Its formula can be rationalized as A6Na6Sn34 + 3·Na4Sn4 (one clathrate layer and three tin tetrahedra). The compound is stable in air and is being currently tested at other conditions. Detailed measurements of its transport properties are under way.

scholarly journals Growth and Characterization of Pure and Doped L-Alanine Tartrate Single Crystals

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
K. Rajesh ◽  
B. Milton Boaz ◽  
P. Praveen Kumar
Keyword(s):  
Single Crystals ◽  
Vickers Microhardness ◽  
Diffraction Method ◽  
Dielectric Studies ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

Single crystals of pure and Lanthanum doped L-Alanine Tartrate were grown by slow evaporation method. The cell parameters were determined using single crystal X-ray diffraction method. To improve the physical properties of the LAT crystal, Lanthanum dopant was added by 2 mol%. ICP studies confirm the presence of Lanthanum in the grown LAT crystal. Transparency range of the crystal was determined using UV-VIS-NIR spectrophotometer. The functional groups of pure and doped LAT crystals were analyzed by FT-IR spectroscopy. Using Vickers microhardness tester, mechanical strength of the material was found. Dielectric studies of pure and doped LAT single crystals were carried out. The doped LAT crystal is found to have efficiency higher than that of pure LAT crystal.

scholarly journals Micro-focused X-ray diffraction characterization of high-quality [6,6]-phenyl-C61-butyric acid methyl ester single crystals without solvent impurities

2013 ◽  
Vol 1 (36) ◽  
pp. 5619 ◽  
Author(s):  
Giuseppe Paternò ◽  
Anna J. Warren ◽  
Jacob Spencer ◽  
Gwyndaf Evans ◽  
Victoria García Sakai ◽  
...  
Keyword(s):  
Methyl Ester ◽  
Single Crystals ◽  
Butyric Acid ◽  
Acid Methyl Ester ◽  
X Ray Diffraction ◽  
High Quality ◽  
X Ray ◽  
Acid Methyl ◽  
Butyric Acid Methyl Ester
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