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Showing papers on "Single crystal published in 2002"


Patent
31 Oct 2002
TL;DR: A natural superlattice homologous single crystal thin film, characterized in that it comprises a composite oxide which is represented by the formula M1M2O3(ZnO)m, is a natural number of 1 or more as discussed by the authors.
Abstract: A natural superlattice homologous single crystal thin film, characterized in that it comprises a composite oxide which is represented by the formula M1M2O3(ZnO)m, wherein M1 is at least one of Ga, Fe, Sc, In, Lu, Yb, Tm, Er, Ho and Y, M2 is at least one of Mn, Fe, Ga, In and Al, and m is a natural number of 1 or more, and has been grown epitaxially on an epitaxial thin film formed on a single crystal substrate, or on said single crystal substrate from which said epitaxial thin film has disappeared, or on a ZnO single crystal; a method for preparing the natural superlattice thin film which comprises depositing the composite oxide, and diffusing the resultant laminated film by heating it. The natural superlattice homologous single crystal thin film is suitably used in an optical device, an electronic device, an X-ray optical device and the like.

1,090 citations


Patent
11 Sep 2002
TL;DR: In this paper, the authors used a homologous compound single crystal InMO 3 (ZnO) m (M=In, Fe, Ga, or Al; m=an integer of 1 to 49) thin film as an active layer to construct a transparent thin film field effect type transistor having a good switching characteristic.
Abstract: PROBLEM TO BE SOLVED: To solve the problem that in ZnO as a transparent oxide semiconductor, it is difficult to reduce an electric conductivity and it is impossible to constitute a normally off field effect type transistor, or as it is difficult to form an amorphous state, an amorphous transistor adaptive for a large area cannot be manufactured. SOLUTION: In a homologous compound InMO 3 (ZnO) m (M=In, Fe, Ga or Al; m=an integer of 1 to 49) single crystal thin film manufactured by a reactive solid-phase epitaxial method, a deviation from a stoichiometry is very small and a good insulator is obtained near room temperatures. By using the homologous compound single crystal InMO 3 (ZnO) m (M=In, Fe, Ga or Al; m=an integer of 1 to 49) thin film as an active layer, a transparent thin film field effect type transistor having a good switching characteristic can be manufactured by a normally off operation. COPYRIGHT: (C)2004,JPO

1,056 citations


Journal ArticleDOI
Xun Wang1, Yadong Li1
TL;DR: In this article, a selective control hydrothermal method has been developed in the preparation of α- and β-MnO2 single-crystal nanowires, which can be influenced by the concentration of NH4+ and SO42-.
Abstract: A selective-control hydrothermal method has been developed in the preparation of α- and β-MnO2 single-crystal nanowires. The crystal structure and morphology of the final products can be influenced by the concentration of NH4+ and SO42-.

978 citations


Journal ArticleDOI
TL;DR: Wurtzite InN films were grown on a thick GaN layer by metalorganic vapor phase epitaxy as discussed by the authors, and growth of a (0001)-oriented single crystalline layer was confirmed by Raman scattering, x-ray diffraction, and reflection high energy electron diffraction.
Abstract: Wurtzite InN films were grown on a thick GaN layer by metalorganic vapor phase epitaxy. Growth of a (0001)-oriented single crystalline layer was confirmed by Raman scattering, x-ray diffraction, and reflection high energy electron diffraction. We observed at room temperature strong photoluminescence (PL) at 0.76 eV as well as a clear absorption edge at 0.7–1.0 eV. In contrast, no PL was observed, even by high power excitation, at ∼1.9 eV, which had been reported as the band gap in absorption experiments on polycrystalline films. Careful inspection strongly suggests that a wurtzite InN single crystal has a true bandgap of 0.7–1.0 eV, and the discrepancy could be attributed to the difference in crystallinity.

692 citations


Journal ArticleDOI
TL;DR: The cubic-tetragonal phase transition of CH 3 NH 3 PbI 3 was investigated by single crystal X-ray diffractometry as discussed by the authors, where the crystal structure was refined at five temperatures in the teragonal phase.
Abstract: The cubic–tetragonal phase transition of CH 3 NH 3 PbI 3 was investigated by single crystal X-ray diffractometry. The crystal structure was refined at five temperatures in the teragonal phase. The PbI 6 octahedron rorates around the c -axis alternatively to construct the SrTiO 3 -type tetragonal structure. A methylammonium ion is partially orderd; 24 disordered states in the cubic phase are reduced to 8. With decreasing temperature, the rotation angle of the octahedron increases monotonically, which indicates it is an order parameter of the cubic-tetragonal transition.

438 citations




Journal ArticleDOI
TL;DR: In this paper, high-resolution neutron powder diffraction and single crystal measurements on the ferromagnetic shape memory compound Ni2MnGa have been carried out, which enabled the sequence of transformations which take place when the unstressed, stoichiometric compound is cooled from 400 to 20 K to be established.
Abstract: High resolution neutron powder diffraction and single crystal measurements on the ferromagnetic shape memory compound Ni2MnGa have been carried out. They enabled the sequence of transformations which take place when the unstressed, stoichiometric compound is cooled from 400 to 20 K to be established. For the first time the crystallographic structure of each of the phases which occur has been determined. At 400 K the compound has the cubic L21 structure, and orders ferromagnetically at TC ≈ 365 K. On cooling below ~ 260 K a super-structure, characterized by tripling of the repeat in one of the 110cubic directions, forms. This phase, known as the pre-martensitic phase, persists down to the structural phase transition at TM ≈ 200 K and can be described by an orthorhombic unit cell with lattice parameters aortho = 1/√2acubic, bortho = 3/√2acubic, cortho = acubic and space group Pnnm. Below TM the compound has a related orthorhombic super-cell with bortho ≈ 7/√2acubic, which can be described within the same space group. The new modulation appears abruptly at TM and remains stable down to at least 20 K.

303 citations


Journal ArticleDOI
TL;DR: In this article, a single-molecule magnet with negative magnetoanisotropy has been found to have a S = 6 ground state with considerable negative magneto-isotropic properties, where the single ion zero-field interactions (DSz2) at each cobalt ion are the origin of the negative magnetosotropy.
Abstract: A cobalt molecule that functions as a single-molecule magnet, [Co4(hmp)4(MeOH)4Cl4], where hmp− is the anion of hydroxymethylpyridine, is reported. The core of the molecule consists of four Co(II) cations and four hmp− oxygen atom ions at the corners of a cube. Variable-field and variable-temperature magnetization data have been analyzed to establish that the molecule has a S=6 ground state with considerable negative magnetoanisotropy. Single-ion zero-field interactions (DSz2) at each cobalt ion are the origin of the negative magnetoanisotropy. A single crystal of the compound was studied by means of a micro-superconducting quantum interference device magnetometer in the range of 0.040–1.0 K. Hysteresis was found in the magnetization versus magnetic field response of this single crystal.

249 citations


Journal ArticleDOI
TL;DR: Using grazing-incidence x-ray diffraction and scanning tunneling microscopy (STM), this article showed that the thermal decomposition of an electronic-grade wafer of 6H-SiC after annealing at increasing temperatures TA between 1080 and 1320°C leads to the layer-by-layer growth of unconstrained, heteroepitaxial single-crystalline graphite.
Abstract: Using grazing-incidence x-ray diffraction and scanning tunneling microscopy (STM), we show that the thermal decomposition of an electronic-grade wafer of 6H-SiC after annealing at increasing temperatures TA between 1080 and 1320 °C leads to the layer-by-layer growth of unconstrained, heteroepitaxial single-crystalline graphite. The limited width of the in-plane diffraction rod profiles of graphite reveals large terraces, with an average size larger than 200 A and a very small azimuthal disorientation. The overlayer is unstrained and adopts the crystalline parameter of bulk graphite even at the smallest coverage studied, which corresponds to a single graphene plane, as inferred from the flat out-of-plane diffraction profile. By increasing TA, additional graphene planes can be grown below this graphite layer from the solid-state decomposition of SiC, forming the AB stacking of Bernal graphite. A C-rich precursor is evidenced in STM by an intrinsic (6×6) reconstruction made of ordered ring or starlike structures. The resulting epitaxial film is indistinguishable from a bulk graphite single crystal.

230 citations


Journal ArticleDOI
TL;DR: In this paper, a strain gradient dependent crystal plasticity approach is used to model the constitutive behavior of polycrystal FCC metals under large plastic deformation, where material points are considered as aggregates of grains, subdivided into several fictitious grain fractions: a single crystal volume element stands for the grain interior whereas grain boundaries are represented by bi-crystal volume elements.
Abstract: A strain gradient dependent crystal plasticity approach is used to model the constitutive behaviour of polycrystal FCC metals under large plastic deformation. Material points are considered as aggregates of grains, subdivided into several fictitious grain fractions: a single crystal volume element stands for the grain interior whereas grain boundaries are represented by bi-crystal volume elements, each having the crystallographic lattice orientations of its adjacent crystals. A relaxed Taylor-like interaction law is used for the transition from the local to the global scale. It is relaxed with respect to the bi-crystals, providing compatibility and stress equilibrium at their internal interface. During loading, the bi-crystal boundaries deform dissimilar to the associated grain interior. Arising from this heterogeneity, a geometrically necessary dislocation (GND) density can be computed, which is required to restore compatibility of the crystallographic lattice. This effect provides a physically based method to account for the additional hardening as introduced by the GNDs, the magnitude of which is related to the grain size. Hence, a scale-dependent response is obtained, for which the numerical simulations predict a mechanical behaviour corresponding to the Hall–Petch effect. Compared to a full-scale finite element model reported in the literature, the present polycrystalline crystal plasticity model is of equal quality yet much more efficient from a computational point of view for simulating uniaxial tension experiments with various grain sizes.

Journal ArticleDOI
TL;DR: In this paper, a bulk crystal of γ-glycine has been grown at ambient temperature from aqueous solution in the presence of small amount of sodium chloride, and the chemical composition of the grown crystal was determined by CHN analysis and infrared spectroscopy.

Journal ArticleDOI
TL;DR: In this article, Nd-doped YAG (Y3Al5O12) ceramics that contained from 1.1 to 4.8 at.% Nd additives and exhibited nearly the same optical properties as those of a single crystal was fabricated by a solid-state reaction method using high-purity powders.

Journal ArticleDOI
TL;DR: In this paper, the structural, electrical and optical properties of a single-crystal aluminum-doped zinc oxide (AZO) film were investigated as a function of substrate deposition temperature and background gas pressure.

Journal ArticleDOI
TL;DR: In this paper, the surface structures of a Nb(100) single crystal in the initial stages of oxidation have been investigated by ultrahigh vacuum (UHV) scanning tunneling microscopy (STM).

Journal ArticleDOI
TL;DR: In this paper, gold Schottky-barrier diodes were fabricated on vapor-phase-grown single-crystal ZnO. Deep-level transient spectroscopy, using these SBDs, revealed the presence of four electron traps, the major two having levels at 0.12 eV and 0.57 below the conduction band.
Abstract: Gold Schottky-barrier diodes (SBDs) were fabricated on vapor-phase-grown single-crystal ZnO. Deep-level transient spectroscopy, using these SBDs, revealed the presence of four electron traps, the major two having levels at 0.12 eV and 0.57 below the conduction band. Comparison with temperature-dependent Hall measurements suggests that the 0.12 eV level has a temperature activated capture cross section with a capture barrier of about 0.06 eV and that it may significantly contribute to the free-carrier density. Based on the concentrations of defects other than this shallow donor, we conclude that the quality of the vapor-phase-grown ZnO studied here supercedes that of other single-crystal ZnO reported up to now.


Journal ArticleDOI
TL;DR: In this paper, the crystal structure of the Cu2Zn/Cd,Hg/SnSe4 compounds were investigated using X-ray powder diffraction and the results showed that these compounds crystallize in the stannite structure (space group I 4 2m).

Journal ArticleDOI
TL;DR: In this paper, the surface treatment of the copper single crystal electrodes was studied in detail, and the reproducibility of the CO2 reduction was greatly improved by using the X-ray back reflection method.

Journal ArticleDOI
Xiangyong Zhao1, Bijun Fang1, Hu Cao1, Yiping Guo1, Haosu Luo1 
TL;DR: In this paper, a detailed study of the dependence of the dielectric and piezoelectric performance on the composition, poling field and crystallographic direction for Pb(Mg 1/3 Nb 2/3 )O 3 PbTiO 3 (PMN-PT) single crystal plates with compositions around the rombohedral-tetragonal morphotropic phase boundary (MPB).
Abstract: This paper presents a detailed study of the dependence of the dielectric and piezoelectric performance on the composition, poling field and crystallographic direction for Pb(Mg 1/3 Nb 2/3 )O 3 PbTiO 3 (PMN–PT) single crystal plates with compositions around the rombohedral–tetragonal morphotropic phase boundary (MPB). The Tmax of the plates lies in the range of 130–160 °C. Influence of poling field in a range of 0–3 kV mm −1 on their properties was investigated. Under appropriate poling conditions and with proper compositions, the plates show excellent piezoelectric property with d 33 larger than 1800 pC N −1 along 〈001〉 and 〈011〉, and 1300 pC N −1 along 〈111〉, respectively. It is also suggested that the relaxor nature of PMN, the domain structure modulation and the MPB effect all play important roles in influencing the piezoelectric performance. The possibility of the existence of the induced orthorhombic or monoclinic phase is also discussed in this paper.

Journal ArticleDOI
23 Jan 2002-Langmuir
TL;DR: In this paper, the structure of the molecular film, determined separately via low-energy electron diffraction, includes a c(23 × √3) stripe phase and c(3 × 2√ 3) saturated phases.
Abstract: The chemisorption of 1-decanethiol on the Au(111) single crystal has been studied with synchrotron-based, high-resolution photoemission spectroscopy with molecular film prepared from both gas-phase dosing and solution immersion to vary surface coverage over a wider range. The structure of the molecular film, determined separately via low-energy electron diffraction, includes a c(23 × √3) stripe phase and c(3 × 2√3) saturated phases. Careful curve fitting of the S 2p2/3 core level reveals that there is only one sulfur species at a binding energy of 162.1 eV in the film and the spectrum of the S 2p core level does not vary with the surface coverage and existence temperature of the decanethiolate. This finding is inconsistent with the sulfur-pairing model proposed based on X-ray scattering and standing wave studies. Up to two C 1s core levels at 284.0 and 285.0 eV can be observed, depending on the surface coverage. Angle-resolved X-ray photoelectron spectroscopy measurements are utilized to provide a direct ...

Journal ArticleDOI
TL;DR: In this article, the tilt angle between the ethane C-C bond and the equatorial plane of the large cage was found to be 23°, in good agreement with the value of 25.2° found previously from NMR studies.

Journal ArticleDOI
TL;DR: In this article, applications of synchrotron X-ray scattering to electrochemistry problems are briefly reviewed ranging from submonolayer level phenomena, through nanometer size phenomena, to submicron size phenomena; that is, covering the full range of the 'interphase' at an electrode surface.

Journal ArticleDOI
TL;DR: Heat-capacity measurements of a 39 microg MgB2 single crystal in fields up to 14 T and below 3 K allow the determination of the low-temperature linear term of the specific heat, its field dependence, and its anisotropy.
Abstract: Heat-capacity measurements of a 39 microg MgB2 single crystal in fields up to 14 T and below 3 K allow the determination of the low-temperature linear term of the specific heat, its field dependence, and its anisotropy. Our results are compatible with two-band superconductivity, the band carrying the smaller gap being isotropic, that carrying the larger gap having an anisotropy of approximately 5. Three different upper critical fields are thus needed to describe the superconducting state of MgB2.

Journal ArticleDOI
TL;DR: In this paper, a large quantity of single-crystal MoO3 nanobelts were synthesized by a low-temperature, simple solution method without using any templates or catalysts.
Abstract: Bulk quantities of single-crystal MoO3 nanobelts were synthesized by a low-temperature, simple solution method without using any templates or catalysts. X-ray powder diffraction, transmission electron microscopy, high-resolution transmission electron microscopy, selected area electron diffraction, and energy-dispersive x-ray analysis indicated that as-synthesized nanobelts were pure orthorhombic structured MoO3 grown along [001], with the lengths up to more than 10 μm, width ranging between 50 and 400 nm, and width-to-thickness ratios of about 5 to 20. The possible growth mechanism and the influence factors were reported.

Journal ArticleDOI
TL;DR: In this article, the authors used photolithography and a reactive ion etching method to fabricate a serially grafted (conjunct) waveguide of DAST with a transparent polymer waveguide.
Abstract: In order to use the large, electro-optic coefficient of a nonlinear optical ionic crystal, 4-(p-dimethylaminostyryl)-1-methylpyridinium tosylate (DAST), a channel optical waveguide structure is needed. We successfully fabricated a waveguide using two methods: by a dry-etching technique and by photo-bleaching. Because DAST has a large optical loss, parts of the waveguide should be composed of a transparent polymer. We used photolithography and a reactive ion etching method to fabricate a serially grafted (conjunct) waveguide of DAST with a transparent polymer waveguide. The waveguide was also fabricated by photobleaching, whereby the refractive indices of the crystal’s a- and b-axes were decreased by degrading the crystal. The cladding part of the DAST waveguide was photobleached by irradiating with UV light. The under- and over-cladding layers of these channel waveguides were composed of a UV-cured resin that did not dissolve the DAST crystal. The loss of the crystal waveguide for the crystal b-direction was around 10 dB/cm, due to the scattering loss of the DAST single crystal.

Journal ArticleDOI
TL;DR: In this paper, single-crystalline GaN nanorods are formed on a sapphire substrate by hydride vapor phase epitaxy (HVPE) and their structural and optical properties are investigated by x-ray diffraction, scanning and transmission electron microscopy, and cathodoluminescence (CL) techniques.
Abstract: Single-crystalline GaN nanorods are formed on a sapphire substrate by hydride vapor phase epitaxy (HVPE). Their structural and optical properties are investigated by x-ray diffraction, scanning and transmission electron microscopy, and cathodoluminescence (CL) techniques. The high density of straight and well-aligned nanorods with a diameter of 80–120 nm formed uniformly over the entire 2 in. sapphire substrate. The x-ray diffraction patterns and transmission electron microscopic images indicate that the formed GaN nanorods are a pure single crystal and preferentially oriented in the c-axis direction. We observed a higher CL peak position of individual GaN nanorods than that of bulk GaN as well as a blueshift of CL peak position with decreasing the diameter of GaN nanorods, which are attributed to quantum confinement effect in one-dimensional GaN nanorods. We demonstrate that the well-aligned, single-crystalline GaN nanorods with high density, high crystal quality, and good spatial uniformity are formed b...

Journal ArticleDOI
TL;DR: In this paper, the electronic anisotropy of the MgB 2 superconductor was studied using the in-plane resistivity measurements in the magnetic field applied perpendicular and parallel to Mg and B planes of Mg b 2 single crystals.
Abstract: We report on the study of the electronic anisotropy of the MgB 2 superconductor using the in-plane resistivity measurements in the magnetic field applied perpendicular and parallel to Mg and B planes of MgB 2 single crystals. The results show the temperature dependent anisotropy of the upper critical field with the anisotropy ratio γ=H c 2 | | /H c 2 increasing from 2.2 close to T c up to about 3 below 30 K. Our estimation of the in-plane and out-of-plane coherence length of about ξ a b (0) = 68 A and ξ c (0) = 23 A and the electronic mean-free path l a b =240 A and l c =60 A, respectively, indicates MgB 2 single crystal approaches the clean limit type-II superconductor.

Journal ArticleDOI
TL;DR: In this article, the change in interface morphology with ionic vacancy concentration and the correlation between interface structure and grain growth behavior in strontium titanate (SrTiO3) have been investigated using single crystals and powder compacts.

Journal ArticleDOI
TL;DR: In this paper, a method of fabricating single crystal silver nanowires based on the electroless deposition of silver into the pores of the polycarbonate membranes by the metal amplification process is presented.
Abstract: We present a method of fabricating single crystal silver nanowires based on the electroless deposition of silver into the pores of the polycarbonate membranes by the metal amplification process. A gold film on one side of the nanoporous membrane is used as the initiation layer for the silver crystal growth, while the pores of the membrane are used for guiding the growth of the silver crystal into a cylindrical nanostructure. Optical microscopy and spectroscopy of individual nanowires, transmission electron microscopy (TEM), and TEM diffraction crystallography were used to characterize the silver nanostructures. The metal amplification technique presents an electroless, simple, and inexpensive solution to the challenge of fabricating silver nanowires for electronic, optical, and biological applications.