Showing papers on "Single crystal published in 1983"
TL;DR: Theoretical and experimental aspects of this method in a single reflection mode are discussed in this paper, where vibrational frequencies of the C-O stretch allow determination of adsorption sites.
947 citations
TL;DR: In this article, a reproducible process for growing a thick single-crystal layer of cubic SiC on a singlecrystal Si wafer by chemical vapor deposition is described, where a buffer layer, grown in situ, is used between the SiC and the Si substrate to minimize the effect of lattice mismatch.
Abstract: A reproducible process is described for growing a thick single-crystal layer of cubic SiC on a single-crystal Si wafer by chemical vapor deposition. A buffer layer, grown in situ, is used between the cubic SiC and the Si substrate to minimize the effect of lattice mismatch. Layers of up to 34 microns thick and several sq cm in area have been grown. Wafers are obtained by chemically removing the Si substrates from the grown layers. Excellent electron channeling patterns produced by these wafers indicate very good crystal quality. Preliminary electrical measurements have yielded electron mobilities up to 380 sq cm/Vs.
862 citations
TL;DR: In this paper, the a.c. conductivity σ(ω) of ionic materials is derived from the new expression ω(0) = A ωpn and the carrier concentration is estimated from σ (0).
435 citations
375 citations
TL;DR: Most of the shallow acceptor levels due to boron in single-crystal silicon can be neutralized by atomic hydrogen at temperatures between 65 and 300 C as discussed by the authors, which can result in a sixfold increase in resistivity.
Abstract: Most of the shallow acceptor levels due to boron in single-crystal silicon can be neutralized by atomic hydrogen at temperatures between 65 and 300\ifmmode^\circ\else\textdegree\fi{}C. This treatment can result in a sixfold increase in resistivity.
353 citations
TL;DR: In this article, the light output was 1.3 times larger than that of the best Bi4Ge3O12, and the decay constant was 60 ns at room temperature.
Abstract: Cerium‐activated phosphors are characterized by their fast luminescence decay. Gadolinium orthosilicate (Gd2SiO5) is a material possessing a high atomic number, and can also play host to the cerium activator. Cerium‐doped Gd2SiO5 single crystals were grown by the Czochralski technique, and their luminescence properties were examined. The light output was 1.3 times larger than that of the best Bi4Ge3O12, and the decay constant was 60 ns at room temperature.
342 citations
Journal Article•
TL;DR: In this article, high-resolution silicon-29 magic-angle sample-spinning NMR spectroscopic studies of a wide range of natural and synthetic silicates indicate considerable overlap among the ranges of isotropic chemical shifts for crystals of different polymer types.
Abstract: High-resolution silicon-29 magic-angle sample-spinning NMR spectroscopic studies of a wide range of natural and synthetic silicates indicate (l) considerable overlap among the ranges of isotropic chemical shifts for crystals of different polymer types. This expands upon the work of Lippmaa et a/. (1980), who found well-separated ranges; (2) a wide range of chemical shift anisotropies (CSA) and asymmetry parameters (q) that are related to symmetry and structure; (3) a relatively poor correlation between isotropic chemical shift and average Si-O bond length; (4) a better correlation between isotropic chemical shift and total cation-oxygen bond strength for the four oxygens ofeach silicon tetrahedron;,and (5) discrepancies between the NMR results and crystal structure refinements for kyanite and wollastonite. These results indicate that both the Si-O bond length-chemical shift and bond strength-chemical shift relationships are useful tools for investigating the structures of crystalline silicates and, perhaps more importantly, silicate glasses, clays, and zeolites that cannot be examined by single crystal X-ray or neutron diffraction methods.
255 citations
TL;DR: A relationship between the a.c. and d.c components of ionic conductivity, established for single crystal Na β-alumina, is critically examined in this article.
225 citations
TL;DR: In this paper, surface alloys were formed by heating the Pt(111) crystal that was covered with a Au multilayer, and the surfaces were characterized with Auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and temperature-programmed desorption (TPD) of CO.
195 citations
TL;DR: In this article, the electronic properties of Me2O3 oxides (Me = Ti, V, Cr) were determined from XPS valence band and core level measurements.
Abstract: The electronic structure behaviour of Me2O3 oxides (Me = Ti, V, Cr) has been determined from XPS valence band and core level measurements. From Ti to Cr sesquioxide the relative intensity of the 3d band increases systematically which can be explained by the (atomic) photoelectric cross section and the number of 3d electrons. Simultaneously the 3d-2p band separation decreases indicating a more stronger band overlap equivalent an enhanced covalent bonding component. The different electrical properties among the corundum structure oxides are determined by the trigonal field splitted a1g and eg orbitals, their occupation and relative energy position at the Fermi level. The observations confirm the change from itinerant to more localized behaviour of d electrons caused by crystal structure parameter change (c/a ratio).
170 citations
TL;DR: In this paper, the authors used backscattering spectrometry and glancing-angle x-ray diffraction to investigate the silicide formation with single crystal Si and amorphous Si.
Abstract: Silicide formation with Ti deposited on single crystal Si and Ti deposited on amorphous Si layers sequentially without breaking the vacuum was investigated using backscattering spectrometry and glancing-angle x-ray diffraction. For Ti deposited on amorphous Si, TiSi2 was formed with a rate proportional to (time)^1/2 and an activation energy of 1.8±0.1 eV. For Ti deposited on single crystal Si, the reaction rate was slower and the silicide layer was nonuniform in thickness. We attribute the difference in behavior to the presences of interfacial impurities in the case where Ti was deposited on single crystal Si.
TL;DR: In this article, the first-order Raman spectra of FeS2, MnS2 and SiP2 were measured at room temperature and the frequencies of all Raman-active phonons were obtained.
TL;DR: The kinetics of formation of anodic oxide films can be derived from measurements of current density iox, thickness d and electrode capacity C in dependence on the polarization potential e and time t.
TL;DR: In this paper, a novel crystal growth technique for silicide epitaxy is presented which utilizes thin silicide (<60 A) template layers to pin the subsequent growth under ultrahigh vacuum conditions.
Abstract: A novel crystal growth technique for silicide epitaxy is presented which utilizes thin silicide (<60 A) template layers to pin the subsequent growth under ultrahigh vacuum conditions. Single crystal NiSi2 films can be grown with either type A or type B orientations on Si (111). Continuous single crystal NiSi2 is grown on Si (100) with a flat interface and uniform thickness. Thick CoSi2 can be grown on Si (111) by a similar process using thicker templates.
TL;DR: The dependence of diffraction peak intensities upon temperature for the scattering of helium from various copper surfaces has been experimentally determined for two incident energies (21 −63 meV) and a large range of incidence angles.
TL;DR: In this paper, the authors studied the dynamics properties of a face centered cubic crystal-vapor system and found that all three faces exhibit a signficant degree of surface disorder and atomic mobility near the bulk melting point.
Abstract: Dynamical properties of the (111), (100), and (110) faces of a face centered cubic crystal–vapor system have been obtained at a series of temperatures along the crystal–vapor coexistence line by molecular dynamics techniques. The particles interact by means of a Lennard‐Jones potential. We find that all three faces exhibit a signficant degree of surface disorder and atomic mobility near the bulk melting point. Although the diffusion coefficients in the surface layers vary markedly, the total surface mass transport is approximately equal for the three faces.
TL;DR: The surface of single crystal MoO 3 has been prepared and examined using LEED, XPS, UPS, and ELS as mentioned in this paper, and the surface periodicity is the same as that of the bulk (010).
TL;DR: In this article, the Mott-Schottky plots of the capacitance data have been observed on zirconium-doped α-Fe 2 O 3 single-crystal electrodes and the energy, volume density and time constant of this level were obtained from impedance measurements over a wide frequency range.
TL;DR: In this paper, the growth rate and degree of supercooling were analyzed in CaMgSi2O6-CaTiAl 2O6 clinopyroxene crystals using seed crystals.
Abstract: Sector zoning has been experimentally reproduced in CaMgSi2O6-CaTiAl2O6 clinopyroxene crystals by isothermal crystallization using seed crystals. Element partitioning in different growth sectors and between the core and rim portions in single crystals was analysed in relation to growth rate R and degree of supercooling Δ T. The TiO2 and Al2O3 contents increase with increase in R and Δ T, but when they are compared between different sectors in a single crystal grown at the same Δ T, they correlate negatively with R. The order of faces in respect of contents of TiO2 and Al2O3 is (100)>(110)≳(010)≳(111) at ΔT= 13° C and 18° C but changes to (110)>(100)>(010)>(111) at Δ T= 25° C. The growth mechanism is concluded to be controlled by interface kinetics at ΔT= 13–25° C for all these faces, while at Δ T=45° C this relation holds for (100) and (010) faces, but not for (110) and (111), based on the growth rate versus supercooling relation and surface microtopographic observations. The interface kinetics play the essential role in the formation of sector zoning, when the layer growth mechanism takes place.
TL;DR: TEM examinations of cross-sectioned Ni electrodeposits grown on oriented substrates show that their structure results of a competition between an epitaxial growth process and a non-epitaxial growing initiated by a substrate independent nucleation as discussed by the authors.
TL;DR: In this paper, the structure of the FeIIIF6 octahedra is derived from single crystal X-ray diffraction data (605 independent reflections) and refined to R = 0.019 (Rω =0.021).
TL;DR: The NASICON structure domain of stability has been investigated in the ZrO 2 -P 2 O 5 -M 2 O-SiO 2 (M = Li, Na, K, Ag) system (Hf, Ti and partial Ta substitutions of Zr ions have also been studied) using X-Ray diffraction and vibrational spectroscopy as discussed by the authors.
TL;DR: In this article, single crystals of a new delafossite-type compound CuYO2 were grown from a Cu2OY2O3 melt by slow cooling from 1210°C.
TL;DR: In this paper, the effect of crystallographic orientation and test temperature on hardness of WC single crystals was investigated along with the hot hardness of poly crystalline tungsten carbide.
Abstract: The effect of crystallographic orientation and test temperature on hardness of WC single crystals was investigated along with the hot hardness of poly crystalline tungsten carbide. Also investigated was the effect of carbide grain size and the amount of binder phase on the hot hardness of some cemented tungsten carbides. The hot hardness of single crystal WC on all major crystallographic orientations evaluated decreases very rapidly for increasing temperature, and the single crystal hardness on its hardest orientation is only about half of the polycrystalline material depending on the test temperature. Because of its polycrystalline character, some cobalt bonded cemented tungsten carbides can be harder than single crystal WC over some intermediate temperature range.
TL;DR: In this article, a well-annealed W(110) single crystal was used as a fast-to-slow positron moderator, and the measured moderator efficiency at room temperature using a 58Co positron source in the backscattering geometry is roughly a factor of three better than the best previously reported Cu(111)+S moderator.
Abstract: A well-annealed W(110) single crystal was used as a fast-to-slow positron moderator. The measured moderator efficiency at room temperature using a58Co positron source in the backscattering geometry isɛ =(3.2±0.4)×10−3, roughly a factor of three better thanɛ for the best previously reported Cu(111)+S moderator. We find a stable positron moderation efficiency over a period of several weeks when maintained at pressures around 10−9 Torr and an energy spreadΔE = 0.7 eV of the emitted slow positrons. An initial attempt was made to fabricate a hybrid Cu on W(110) moderator, which yieldedɛ of about 1.2×10−3 after annealing.
TL;DR: In this article, the authors describe new variations of the Ag-crystal decoration technique which expand its applicability and make it far easier to use, eliminating the need for tedious dark room procedures in the handling of the nuclear AgBr emulsions 4'5.
Abstract: There is a limited number of techniques to reveal the microstructural distribution of hydrogen near a surface or at the exit points of the hydrogen flux from the metal into the gas phase. The most prominent techniques are tritium autoradiography, I ion microprobe experiments, 2,3 Ag-crystal decoration, 4'5 and several nuclear techniques (see, for example, Reference 6). In particular, the Ag-crystal decoration technique 4'5 uses the special activity of atomic hydrogen on a metal surface to reduce Ag ions in AgBr into elemental Ag. It is therefore sensitive to the hydrogen flux across the interface. This Communication describes new variations of the Ag-crystal decoration technique which expand its applicability and make it far easier to use. Also, the need for tedious dark room procedures in the handling of the nuclear AgBr emulsions 4'5 is eliminated. The principle of the present techniques is the reduction of dissolved Ag, Au, and Pd compounds by atomic hydrogen and the subsequent formation of visible elemental metal crystals at surface locations of high hydrogen activity. The samples used in this work were annealed high-purity polycrystalline Ni sheet and single crystal Ni slabs which were electropolished prior to cathodic hydrogen charging (in 0.1 N H2804, i = 10 to 100 mA/cm 2, t 103 S, T = 20 ~ Several areas on each surface were also masked off with acid resistant lacquer (which was removed right after loading) to have "reference areas" which were not exposed to hydrogen.* After hydrogen loading, the surfaces were
TL;DR: In this paper, the growth of metastable semiconductors with pseudobinary phase diagram was reviewed and an attempt was made to establish a foundation for understanding and modeling crystal growth of this new class of semiconducting materials.
Abstract: Several research groups have recently reported the growth of metastable semiconductors which were not only single phase but, in many cases, high quality single crystals. The systems reported to date include the (III–V)1−xIVx alloys (GaAs)1−xSix, (GaAs)1−xGex, and (GaSb)1−x Gex, the nonisostructural alloys Pb1−xCdxS, InSb1−xBix, and Ge1−xSnx, elemental α‐Sn, and GaAs1−xSbx with x values within the miscibility gap. Several of these systems have been grown with compositions ranging across the pseudobinary phase diagram and have been found to exhibit good thermal stability against phase separation at temperatures ≥500 °C. In addition to crystal growth studies, structural, optical, electrical, lattice dynamic, and thermodynamic measurements have been carried out. These results are reviewed and an attempt is made to establish a foundation for understanding and modeling crystal growth of this new class of semiconducting materials.
TL;DR: In this paper, the direct current conductivity of MgO single crystals of nominally highest purity (with respect to cation impurities), grown by arc-fusion, was studied in argon or oxygen between 500-1200 K with special reference to both hysteresis effects during heating and cooling cycles and conductivity phenomena which occur underneath the surface in a thin subsurface zone.
TL;DR: In this paper, the crystal structures have been determined from automated three-dimensional single crystal X-ray diffraction analyses, which yielded final weighted R-values equal to 00.035, 0.037, and 0.036, respectively.
TL;DR: In this paper, a silicon wafer was implanted with 200 keV oxygen to dosss of up to 2.4 × 10 18 O + /cm 2 at implantation temperatures of 325°C to 600°C.