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Sample records for cubic inn films

  1. Growth, Nitrogen Vacancy Reduction and Solid Solution Formation in Cubic GaN Thin Films and the Subsequent Fabrication of Superlattice Structures Using AIN and InN

    Science.gov (United States)

    1992-12-01

    AD-A258 804 Final Technical Report Ii Growth, Nitrogen Vacancy Reduction and Solid Solution Formation in Cubic GaN Thin Films and the Subsequent...Technical 6/1/86-12/31/92 4. TITLE AND SUBTITLE Growth, Nitrogen Vacancy Reduction and 5. FUNDING NUMBERS Solid Solution Formation in Cubic GaN Thin...According to the structural and chemical analyses, there is no reason to believe that a homogeneous solid solution close to this composition had

  2. Natural oxidation of InN quantum dots: the role of cubic InN

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, David; Lozano, Juan G.; Herrera, Miriam; Garcia, Rafael [Departamento de Ciencia de los Materiales e Ingenieria Metalurgica y Quimica Inorganica, Universidad de Cadiz, Apdo. 40, E-11510 Puerto Real (Cadiz) (Spain); Browning, Nigel D. [Department of Chemical Engineering and Materials Science, University of California-Davis, One Shields Ave, Davis, CA 95616 (United States); Chemistry, Materials and Life Sciences Directorate, Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, CA 94550 (United States); Ruffenach, Sandra; Briot, Olivier

    2010-01-15

    The natural aging process occured in indium nitride quantum dots (QDs) heterostructures as a consequence of exposure to the atmosphere has been studied by means of transmission electron microscopy and electron beam related techniques. The comparison between GaN-capped and uncapped InN QDs kept at room conditions during 36 months indicates the structural changes that take place. While the capping layer seems to act in a protective way avoiding any change in the QDs, the uncapped structures suffer a series of phase transformations, where the original wurtzite structure is replaced by a layer of cubic phases. The main constituent of this layer is shown to be bcc-In{sub 2}O{sub 3} formed by the substitution of the nitrogen atoms by oxygen from the atmosphere. This supposes a transformation from a hexagonal to a cubic structure, explained by the existence of an oxygen-rich cubic InN acting as an intermediate phase. The difference in the formation enthalpy between the original and the final product, together with the good match between the crystals would explain this transformation that shows the high instability of InN at environmental conditions. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Growth, Nitrogen Vacancy Reduction and Solid Solution Formation in Cubic GaN Thin Films and the Subsequent Fabrication of Superlattice Structures Using AIN and InN

    Science.gov (United States)

    1992-02-01

    n majmiy of t studies have Ween conduted on pu. gallium nitrid thin films having the wutzite scur, and this emphasis contu.s to we pnt day. Recent...adherence and thermal contact The s-bsuates underwent an initial low temperature (=701C) outgasing in the load lock followed by slow heating in the...SEM. Several samples became p-type, as confirmed by the I-V and thermal probe measurements. Figure 2 shows the change in the I-V curves obtained from

  4. Growth, Nitrogen Vacancy Reduction and Solid Solution Formation in Cubic GaN Thin Films and the Subsequent Fabrication of Superlattice Structures Using AlN and InN

    Science.gov (United States)

    1992-06-01

    AD-A253 331 Semiannual Report Growth, Nitrogen Vacancy Reduction and Solid Solution Formation in Cubic GaN Thin Films and the Subsequent Fabrication...Growth, Nitrogen Vacancy Reduction and Solid Solution Formation in Cubic GaN Thin Films and the Subsequent Fabrication of Superlattice Structures Using...34 substrates, such as using a graded AlxGal-xN solid solution as a buffer layer. E. Conclusion We have shown that in the use of our modified gas source MBE

  5. Growth, Nitrogen Vacancy Reduction and Solid Solution Formation in Cubic GaN Thin Films and the Subsequent Fabrication of Superlattice Structures Using AlN and InN

    Science.gov (United States)

    1990-07-01

    that the BGaN film remained predominantly single crystal, but shows both a normal cubic [110] pattern and a second hexagonal pattern [0110]. By contrast...27 Transmission electron microscopy (iEM) was used (Hitachi H-800) to more closely examine the microstructural evolution of the BN/ BGaN /GaN epitaxial...area diffraction (SAD) also showed the BGaN layer to be a mixture of cubic and wurtzitic phases. This layer was heavily faulted. The latter phenomenon

  6. Growth, Nitrogen Vacancy Reduction and Solid Solution Formation in Cubic GaN Thin Films and Subsequent Fabrication of Superlattice Structures Using AlN and InN

    Science.gov (United States)

    1990-12-01

    Laboratories, Inc. 3. Structural Analysis Reflection high-energy electron diffraction performed during growth indicated that the BGaN film remained...was used (Hitachi H-800) to more closely examine the microstructural evolution of the BN/ BGaN /GaN epitaxial films. Cross-section TEM specimens were... BGaN layer to be a mixture of cubic and wurtzitic phases. This layer was heavily faulted. The latter phenomenon is to be expected given the high

  7. Tetragonal Distortion of InN Thin Films by RBS/Channeling

    Institute of Scientific and Technical Information of China (English)

    DING Zhi-Bo; WU Wei; WANG Kun; FA Tao; YAO Shu-De

    2009-01-01

    Rutherford backscattering and channeling spectrometry (RBS/C) are used to identify the crystalline quality (Xmin = 4.87%) of an InN thin film as a function of depth,and make a non-destructive quantitative analysis of the structure,in order to analyze the tetragonal distortion of the InN thin film at the depth determined.

  8. The growth temperatures dependence of optical and electrical properties of InN films

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    InN films grown on sapphire at different substrate temperatures from 550℃ to 700℃ by metalorganic chemical vapor deposition were investigated. The low-temperature GaN nucleation layer with high-temperature annealing (1100℃) was used as a buffer for main InN layer growth. X-ray diffraction and Raman scattering measurements reveal that the quality of InN films can be improved by increasing the growth temperature to 600℃. Further high substrate temperatures may promote the thermal decomposition of InN films and result in poor crystallinity and surface morphology. The photoluminescence and Hall measurements were employed to characterize the optical and electrical properties of InN films,which also indicates strong growth temperature dependence. The InN films grown at temperature of 600℃ show not only a high mobility with low carrier concentration,but also a strong infrared emission band located around 0.7 eV. For a 600 nm thick InN film grown at 600℃,the Hall mobility achieves up to 938 cm2/Vs with electron concen-tration of 3.9×1018 cm-3.

  9. Anomalous magnetism of superconducting Mg-doped InN film

    Directory of Open Access Journals (Sweden)

    P. H. Chang

    2016-02-01

    Full Text Available We report on the Meissner effect of Mg-doped InN film with superconducting transition onset temperature Tc,onset of 5 K. Mg-doped InN is magnetically ordered and exhibits a simultaneous first-order magnetic and electric transition near 50 K. Its behavior is similar to that of iron-based superconductors. A strong correlation is proposed to exist between structural distortion and superconductivity when Mg is doped into InN. The suppression of magnetic ordering close to Tc by doping is further demonstrated by anisotropic magnetoresistance and M-H measurements. The findings suggest that the superconducting mechanism in the system may not be conventional BCS.

  10. Influence of N2 Flux on InN Film Deposition on Sapphire (0001) Substrates by ECR-PEMOCVD

    Institute of Scientific and Technical Information of China (English)

    ZHOU Zhi-Feng; QIN Fu-Wen; ZANG Hai-Rong; ZHANG Dong; CHEN Wei-Ji; ZHI An-Bo; LIU Xing-Long; YU Bo; JIANG Xin

    2011-01-01

    Highly preferred InN films are deposited on sapphire (0001) substrates by electron cyclotron resonance plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD) without using a buffer layer. The structure, surface morphological and electrical characteristics of InN are investigated by in-situ reflection high energy electron diffraction, x-ray diffraction, x-ray photoelectron spectroscopy, atomic force microscopy and Hall effect measurement. The quality of the as-grown InN films is markedly improved at the optimized N2 flux of 100sccm.The results show that the properties of the films are strongly dependent on N2 flux.%@@ Highly preferred InN Rims are deposited on sapphire (0001) substrates by electron cyclotron resonance plasma enhanced metal organic chemical vapor deposition (ECR-PEMOCVD) without using a buffer layer.The structure, surface morphological and electrical characteristics of InN are investigated by in-situ reflection high energy electron diffraction, x-ray diffraction, x-ray photoelectron spectroscopy, atomic force microscopy and Hall effect measurement.The quality of the as-grown InN films is markedly improved at the optimized N2 flux of 100 sccm.The results show that the properties of the Rims are strongly dependent on N2 flux.

  11. Tight-binding branch-point energies and band offsets for cubic InN, GaN, AlN, and AlGaN alloys

    Science.gov (United States)

    Mourad, Daniel

    2013-03-01

    Starting with empirical tight-binding band structures, the branch-point (BP) energies and resulting valence band offsets for the zincblende phase of InN, GaN, and AlN are calculated from their k-averaged midgap energy. Furthermore, the directional dependence of the BPs of GaN and AlN is discussed using the Green's function method of Tersoff. We then show how to obtain the BPs for binary semiconductor alloys within a band-diagonal representation of the coherent potential approximation and apply this method to cubic AlGaN alloys. The resulting band offsets show good agreement to available experimental and theoretical data from the literature. Our results can be used to determine the band alignment in isovalent heterostructures involving pure cubic III-nitrides or AlGaN alloys for arbitrary concentrations.

  12. Low pressure growth of cubic boron nitride films

    Science.gov (United States)

    Ong, Tiong P. (Inventor); Shing, Yuh-Han (Inventor)

    1997-01-01

    A method for forming thin films of cubic boron nitride on substrates at low pressures and temperatures. A substrate is first coated with polycrystalline diamond to provide a uniform surface upon which cubic boron nitride can be deposited by chemical vapor deposition. The cubic boron nitride film is useful as a substitute for diamond coatings for a variety of applications in which diamond is not suitable. any tetragonal or hexagonal boron nitride. The cubic boron nitride produced in accordance with the preceding example is particularly well-suited for use as a coating for ultra hard tool bits and abrasives, especially those intended to use in cutting or otherwise fabricating iron.

  13. Growth and Characterization of InN Thin Films on Sapphire by MOCVD

    Institute of Scientific and Technical Information of China (English)

    XIE Zi-Li; ZHANG Rong; XIU Xiang-Qian; LIU Bin; LI Liang; HAN Ping; GU Shu-Lin; SHI Yi; ZHENG You-Dou

    2007-01-01

    Indium nitride thin films are grown on sapphire substrates by metal-organic chemical vapour deposition(MOCVD).By employing three-step layer buffers,the mirror-like layers on two-inch sapphire wafers have been obtained.The structural,optical and electrical characteristics of InN are investigated by x-ray diffraction,scanning electron microscopy,atomic force microscopy,photoluminescence and infrared optical absorpton.The photoluminescence and the absorption studies of the materials reveal a marked energy bandgap structure around 0.70 eV at room temperature.The room-temperature Hall mobility and carrier concentration of the film are typically 939 cm2/Vs,and 3.9×1018cm-3,respectively.

  14. Photonic Crystal Cavities in Cubic Polytype Silicon Carbide Films

    CERN Document Server

    Radulaski, Marina; Buckley, Sonia; Rundquist, Armand; Provine, J; Alassaad, Kassem; Ferro, Gabriel; Vučković, Jelena

    2013-01-01

    We present the design, fabrication, and characterization of high quality factor and small mode volume planar photonic crystal cavities from cubic (3C) thin films (thickness ~ 200 nm) of silicon carbide (SiC) grown epitaxially on a silicon substrate. We demonstrate cavity resonances across the telecommunications band, with wavelengths from 1250 - 1600 nm. Finally, we discuss possible applications in nonlinear optics, optical interconnects, and quantum information science.

  15. High-quality InN films on MgO (100) substrates: The key role of 30° in-plane rotation

    Energy Technology Data Exchange (ETDEWEB)

    Compeán García, V. D.; López Luna, E.; Rodríguez, A. G.; Vidal, M. A. [Coordinación para la Innovación y Aplicación de la Ciencia y Tecnología (CIACyT), Universidad Autónoma de San Luis Potosí (UASLP), Álvaro Obregón 64, 78000 San Luis Potosí (Mexico); Orozco Hinostroza, I. E. [Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José 2055, Col. Lomas 4a Sección, 78216 San Luis Potosí (Mexico); Escobosa Echavarría, A. [Electric Engineering Department, Centro de Investigación y Estudios Avanzados del IPN, Apartado Postal 14-740, 07000 México D.F. (Mexico)

    2014-05-12

    High crystalline layers of InN were grown on MgO(100) substrates by gas source molecular beam epitaxy. Good quality films were obtained by means of an in-plane rotation process induced by the annealing of an InN buffer layer to minimize the misfit between InN and MgO. In situ reflection high-energy electron diffraction showed linear streaky patterns along the [011{sup ¯}0] azimuth and a superimposed diffraction along the [112{sup ¯}0] azimuth, which correspond to a 30° α-InN film rotation. This rotation reduces the mismatch at the MgO/InN interface from 19.5% to less than 3.5%, increasing the structural quality, which was analyzed by high-resolution X-ray diffraction and Raman spectroscopy. Only the (0002) c plane diffraction of α-InN was observed and was centered at 2θ = 31.4°. Raman spectroscopy showed two modes corresponding to the hexagonal phase: E1(LO) at 591 cm{sup −1} and E2(high) at 488 cm{sup −1}. Hall effect measurements showed a carrier density of 9 × 10{sup 18} cm{sup −3} and an electron Hall mobility of 340 cm{sup 2}/(V s) for a film thickness of 140 nm.

  16. Field-effect transistors based on cubic indium nitride.

    Science.gov (United States)

    Oseki, Masaaki; Okubo, Kana; Kobayashi, Atsushi; Ohta, Jitsuo; Fujioka, Hiroshi

    2014-02-04

    Although the demand for high-speed telecommunications has increased in recent years, the performance of transistors fabricated with traditional semiconductors such as silicon, gallium arsenide, and gallium nitride have reached their physical performance limits. Therefore, new materials with high carrier velocities should be sought for the fabrication of next-generation, ultra-high-speed transistors. Indium nitride (InN) has attracted much attention for this purpose because of its high electron drift velocity under a high electric field. Thick InN films have been applied to the fabrication of field-effect transistors (FETs), but the performance of the thick InN transistors was discouraging, with no clear linear-saturation output characteristics and poor on/off current ratios. Here, we report the epitaxial deposition of ultrathin cubic InN on insulating oxide yttria-stabilized zirconia substrates and the first demonstration of ultrathin-InN-based FETs. The devices exhibit high on/off ratios and low off-current densities because of the high quality top and bottom interfaces between the ultrathin cubic InN and oxide insulators. This first demonstration of FETs using a ultrathin cubic indium nitride semiconductor will thus pave the way for the development of next-generation high-speed electronics.

  17. Characterizations of Cubic ZnMgO Films Grown on Si(111) at Low Substrate Temperature

    Institute of Scientific and Technical Information of China (English)

    邱东江; 吴惠桢; 陈乃波; 徐天宁

    2003-01-01

    Cubic ZnMgO thin films in the (100) orientation were grown on Si (111) substrates by reactive electron beamevaporation at low substrate temperature. X-ray photoelectron spectroscopy (XPS) analyses show that Mgcontent as high as 75 at.% in the cubic ZnMgO film can be obtained. Secondary ion mass spectroscopy (SIMS)measurement indicates the evidence of Mg richness in the interface between the ZnMgO film and the Si substrate,and it is probably the primary reason to form the MgO-like cubic ZnMgO structures rather than the wurtziteone. The optical band gap of cubic ZnMgO is estimated to be 5.76eV, which was measured by the transmissionspectrum of the cubic ZnMgO film grown on the sapphire substrate under the same growth condition with thaton Si (111). The band gap is of 2.39eV blueshifted compared with that of ZnO (3.37eV), which should renderapplications in the fabrication of ZnMgO-related heterostructures.

  18. Low energy radiation stability of nano-crystalline cubic Zirconia films

    Science.gov (United States)

    Kalita, Parswajit; Ghosh, Santanu; Avasthi, Devesh K.

    2016-07-01

    The radiation stability of nano-crystalline cubic Zirconia films was investigated under 41 keV He ion irradiation. These ions were chosen to simulate alpha particles (produced during fission events) because of the similar electronic energy loss in Zirconia. The ZrO2 films, with an average grain size of 8 nm, were grown on Si (1 0 0) substrates by electron beam assisted thermal evaporation. Although the cubic structure was retained upon irradiation, a slight reduction in crystallinity in the irradiated films was detected as compared to the as-deposited film. No bulk amorphization was however observed for any of the fluences and hence these films are radiation tolerant to alpha particles.

  19. Nanotwin hardening in a cubic chromium oxide thin film

    Directory of Open Access Journals (Sweden)

    Kazuma Suzuki

    2015-09-01

    Full Text Available NaCl-type (B1 chromium oxide (CrO has been expected to have a high hardness value and does not exist as an equilibrium phase. We report a B1-based Cr0.67O thin film with a thickness of 144 nm prepared by pulsed laser deposition as an epitaxial thin film on a MgO single crystal. The thin film contained a number of stacking faults and had a nanotwinned structure composed of B1 with disordered vacancies and corundum structures. The Cr0.67O thin film had a high indentation hardness value of 44 GPa, making it the hardest oxide thin film reported to date.

  20. Dislocation and Elastic Strain in an InN Film Characterized by Synchrotron Radiation X-Ray Diffraction and Rutherford Backscattering/Channeling

    Institute of Scientific and Technical Information of China (English)

    CHENG Feng-Feng; FA Tao; WANG Xin-Qiang; YAO Shu-De

    2012-01-01

    Dislocation information and strain-related tetragonal distortion as well as crystalline qualities of a 2-μm-thick InN film grown by molecular beam epitaxy (MBE) are characterized by Rutherford backscattering/channeling (RBS/C) and synchrotron radiation x-ray diffraction (SR-XRD).The minimum yield xmin=2.5% deduced from the RBS/C results indicates a fairly good crystalline quality.From the SR-XRD results,we obtain the values of the screw and edge densities to be ρscrew =7.0027 X 109 and ρedge =8.6115 × 109 cm-2,respectively.The tetragonal distortion of the sample is found to be -0.27 % by angular scans,which is close to the -0.28 % derived by SR-XRD.The value of |e(⊥)/e‖| =0.6742 implies that the InN layer is much stiffer along the a axis than that along the c axis,where e‖ is the parallel elastic strain,and e⊥ is the perpendicular elastic strain.Photoluminescence results reveal a main peak of 0.653eV with the linewidth of 60meV,additional shoulder band could be due to impurities and related defects.%Dislocation information and strain-related tetragonal distortion as well as crystalline qualities of a 2-μm-thick InN film grown by molecular beam epitaxy (MBE) are characterized by Rutherford backscattering/'channeling (RBS/C) and synchrotron radiation x-ray diffraction (SR-XRD). The minimum yield Xmin=2.5% deduced from the RBS/C results indicates a fairly good crystalline quality. From the SR-XRD results, we obtain the values of the screw and edge densities to be pscrew = 7.0027 ×109 and pedge = 8.6115 ×109 cm-2, respectively. The tetragonal distortion of the sample is found to be-0.27% by angular scans, which is close to the -0.28 % derived by SR-XRD. The value of |e⊥/e|| | = 0.6742 implies that the InN layer is much stiffer along the a axis than that along the c axis, where e|| is the parallel elastic strain, and e⊥ is the perpendicular elastic strain. Photoluminescence results reveal a main peak of 0.653eV with the linewidth of 60me

  1. Ion-induced stress relaxation during the growth of cubic boron nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Abendroth, B.E.

    2004-08-01

    in this thesis the deposition of cubic boron nitride films by magnetron sputtering is described. The deposition process is analyzed by Langmuir-probe measurement and energy resolved mass spectroscopy. the films are studied by stress measurement, spectroscopic ellipsometry, infrared spectroscopy, elastic recoil detection analysis, Rutherford backscattering spectroscopy, X-ray absorption near edge spectroscopy, X-ray diffraction, and transmission electron microscopy. Discussed are the stress relaxation and the microstructure and bonding characteristics together with the effects of ion bombardement. (HSI)

  2. Applications of Cubic MgZnO Thin Films in Metal-Insulator-Silicon Structures

    Institute of Scientific and Technical Information of China (English)

    LIANG Jun; WU Hui-Zhen; LAO Yan-Feng; QIU Dong-Jiang; CHEN Nai-Bo; XU Tian-Ning

    2004-01-01

    @@ Cubic Mgo.55Zno.45O thin film alloys have been deposited on Si substrates at low growth temperature. The topography of the cross section of the epitaxial film by scanning electronic microscope demonstrates good mor phology and high interfacial quality. The high (001) orientation and wide band-gap (Eg > 5.5 eV) of the cubic Mgo.55Zno.45 O thin films accord with the guidelines for metal-insulator-silicon (MIS) device applications. Using the cubic ternary thin films as insulators, MIS structures have been fabricated. The capacitance-voltage measurements show the flat band voltage shift VFB of11.8 V and mobile ion density Dmc of 5.57 × 1010 cm-2 for the MIS structure. Leakage current density as low as ~ 10-7 A/cm2 is obtained at E = 700 kV/cm by the currentvoltage measurements. These unique structural and electrical properties of the fabricated MIS devices indicate that cubic MgZnO materials could become a new candidate for high-κ dielectrics used in silicon integrated circuit technologies.

  3. Structure and Luminescence Properties of Eu3+-Doped Cubic Mesoporous Silica Thin Films

    Directory of Open Access Journals (Sweden)

    Lu Qingshan

    2010-01-01

    Full Text Available Abstract Eu3+ ions-doped cubic mesoporous silica thin films with a thickness of about 205 nm were prepared on silicon and glass substrates using triblock copolymer as a structure-directing agent using sol–gel spin-coating and calcination processes. X-ray diffraction and transmission electron microscopy analysis show that the mesoporous silica thin films have a highly ordered body-centered cubic mesoporous structure. High Eu3+ ion loading and high temperature calcination do not destroy the ordered cubic mesoporous structure of the mesoporous silica thin films. Photoluminescence spectra show two characteristic emission peaks corresponding to the transitions of5D0-7F1 and 5D0-7F2 of Eu3+ ions located in low symmetry sites in mesoporous silica thin films. With the Eu/Si molar ratio increasing to 3.41%, the luminescence intensity of the Eu3+ ions-doped mesoporous silica thin films increases linearly with increasing Eu3+ concentration.

  4. Structure and luminescence properties of eu3+-doped cubic mesoporous silica thin films.

    Science.gov (United States)

    Lu, Qingshan; Wang, Zhongying; Wang, Peiyu; Li, Jiangong

    2010-02-11

    Eu3+ ions-doped cubic mesoporous silica thin films with a thickness of about 205 nm were prepared on silicon and glass substrates using triblock copolymer as a structure-directing agent using sol-gel spin-coating and calcination processes. X-ray diffraction and transmission electron microscopy analysis show that the mesoporous silica thin films have a highly ordered body-centered cubic mesoporous structure. High Eu3+ ion loading and high temperature calcination do not destroy the ordered cubic mesoporous structure of the mesoporous silica thin films. Photoluminescence spectra show two characteristic emission peaks corresponding to the transitions of5D0-7F1 and 5D0-7F2 of Eu3+ ions located in low symmetry sites in mesoporous silica thin films. With the Eu/Si molar ratio increasing to 3.41%, the luminescence intensity of the Eu3+ ions-doped mesoporous silica thin films increases linearly with increasing Eu3+ concentration.

  5. A probabilistic model of the electron transport in films of nanocrystals arranged in a cubic lattice

    Energy Technology Data Exchange (ETDEWEB)

    Kriegel, Ilka [Department of Nanochemistry, Istituto Italiano di Tecnologia (IIT), via Morego, 30, 16163 Genova (Italy); Scotognella, Francesco, E-mail: francesco.scotognella@polimi.it [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Center for Nano Science and Technology@PoliMi, Istituto Italiano di Tecnologia, Via Giovanni Pascoli, 70/3, 20133 Milan (Italy)

    2016-08-01

    The fabrication of nanocrystal (NC) films, starting from colloidal dispersion, is a very attractive topic in condensed matter physics community. NC films can be employed for transistors, light emitting diodes, lasers, and solar cells. For this reason the understanding of the film conductivity is of major importance. In this paper we describe a probabilistic model that allows the prediction of the conductivity of NC films, in this case of a cubic lattice of Lead Selenide or Cadmium Selenide NCs. The model is based on the hopping probability between NCs. The results are compared to experimental data reported in literature. - Highlights: • Colloidal nanocrystal (NC) film conductivity is a topic of major importance. • We present a probabilistic model to predict the electron conductivity in NC films. • The model is based on the hopping probability between NCs. • We found a good agreement between the model and data reported in literature.

  6. Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Borghi, F.; Lenardi, C.; Podestà, A.; Milani, P., E-mail: pmilani@mi.infn.it [CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); Sogne, E. [CIMAINA and Dipartimento di Fisica, Università degli Studi di Milano, via Celoria 16, 20133 Milano (Italy); European School of Molecular Medicine (SEMM), IFOM-IEO, Milano (Italy); Merlini, M. [Dipartimento di Scienze della Terra “Ardito Desio”, Università degli Studi di Milano, via Mangiagalli 32, 20133 Milano (Italy); Ducati, C. [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom)

    2016-08-07

    Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments.

  7. Vector magneto-optical sensor based on transparent magnetic films with cubic crystallographic symmetry

    Science.gov (United States)

    Rogachev, A. E.; Vetoshko, P. M.; Gusev, N. A.; Kozhaev, M. A.; Prokopov, A. R.; Popov, V. V.; Dodonov, D. V.; Shumilov, A. G.; Shaposhnikov, A. N.; Berzhansky, V. N.; Zvezdin, A. K.; Belotelov, V. I.

    2016-10-01

    The concept of vector magneto-optical magnetometry is proposed and experimentally demonstrated. The key element of the vector magnetometer is a transparent high Faraday activity magnetic film with a cubic crystal lattice. Magnetocrystalline anisotropy of the film leads to the three dimensional trajectory of the film magnetization when the magnetization is rotated by the control magnetic field. It makes the magnetization sensitive to all three components of the external magnetic field. This field can be found from the harmonic composition of the Faraday rotation dependence on the azimuth angle of the control magnetic field. The demonstrated vector magnetometer is promising for mapping and visualization of ultra small magnetic fields.

  8. Cluster-assembled cubic zirconia films with tunable and stable nanoscale morphology against thermal annealing

    KAUST Repository

    Borghi, F.

    2016-08-05

    Nanostructured zirconium dioxide (zirconia) films are very promising for catalysis and biotechnological applications: a precise control of the interfacial properties of the material at different length scales and, in particular, at the nanoscale, is therefore necessary. Here, we present the characterization of cluster-assembled zirconia films produced by supersonic cluster beam deposition possessing cubic structure at room temperature and controlled nanoscale morphology. We characterized the effect of thermal annealing in reducing and oxidizing conditions on the crystalline structure, grain dimensions, and topography. We highlight the mechanisms of film growth and phase transitions, which determine the observed interfacial morphological properties and their resilience against thermal treatments. Published by AIP Publishing.

  9. Void nucleation in biaxially strained ultrathin films of face-centered cubic metals

    Science.gov (United States)

    Kolluri, Kedarnath; Gungor, M. Rauf; Maroudas, Dimitrios

    2007-05-01

    We report an analysis of void nucleation as a relaxation mechanism in freestanding biaxially strained ultrathin films of face-centered cubic metals based on large-scale molecular-dynamics simulations. Above a critical strain level, multiple threading dislocations are emitted from the film surface. The surface step traces formed by gliding dislocations on intersecting and on adjacent parallel glide planes lead to formation and growth of surface pits and grooves, while vacancies form due to gliding of jogged dislocations and dislocation intersections. Coalescence of the surface pits with vacancy clusters is the precursor to the formation of a larger void extending across the film.

  10. Growth-Parameter Spaces and Optical Properties of Cubic Boron Nitride Films on Si(001)

    Institute of Scientific and Technical Information of China (English)

    FAN Ya-Ming; ZHANG Xing-Wang; YOU Jing-Bi; YING Jie; TAN Hai-Ren; CHEN Nuo-Fu

    2009-01-01

    Cubic boron nitride (c-BN) films were deposited on Si(O01) substrates in an ion beam assisted deposition (IBAD)system under various conditions, and the growth parameter spaces and optical properties of c-BN films have been investigated systematically. The results indicate that suitable ion bombardment is necessary for the growth of c-BN films, and a well defined parameter space can be established by using the P/a-parameter. The refractive index of BN films keeps a constant of 1.8 for the c-BN content lower than 50%, while for c-BN films with higher cubic phase the refractive index increases with the c-BN content from 1.8 at χc = 50% to 2.1 at χc = 90%.Furthermore, the relationship between n and p for BN films can be described by the Anderzon-Schreiber equation,and the overlap field parameter γ is determined to be 2.05.

  11. Growth and characterization of cubic SiC single-crystal films on Si

    Science.gov (United States)

    Powell, J. Anthony; Matus, L. G.; Kuczmarski, Maria A.

    1987-01-01

    Morphological and electrical characterization results are presented for cubic SiC films grown by chemical vapor deposition on single-crystal Si substrates. The films, up to 40 microns thick, were characterized by optical microscopy, (SEM), (TEM), electron channeling, surface profilometry, and Hall measurements. A variety of morphological features observed on the SiC films are described. Electrical measurements showed a decrease in the electron mobility with increasing electron carrier concentration, similar to that observed in Si. Room-temperature electron mobilities up to 520 sq cm/V-s (at an electron carrier concentration of 5 x 10 to the 16th/cu cm) were measured. Finally, a number of parameters believed to be important in the growth process were investigated, and some discussion is given of their possible effects on the film characteristics.

  12. The electrical properties of sulfur-implanted cubic boron nitride thin films

    Institute of Scientific and Technical Information of China (English)

    Deng Jin-Xiang; Qin Yang; Kong Le; Yang Xue-Liang; Li Ting; Zhao Wei-Ping; Yang Ping

    2012-01-01

    Cubic boron nitride (c-BN) thin films are deposited on p-type Si wafers using radio frequency (RF) sputtering and then doped by implanting S ions.The implantation energy of the ions is 19 keV,and the implantation dose is between 1015 ions/cm2 and 1016 ions/cm2.The doped c-BN thin films are then annealed at a temperature between 400 ℃ and 800 ℃.The results show that the surface resistivity of doped and annealed c-BN thin films is lowered by two to three orders,and the activation energy of c-BN thin films is 0.18 eV.

  13. Evaluation of multiaxial stress in textured cubic films by x-ray diffraction

    Institute of Scientific and Technical Information of China (English)

    Zhang Jian-Min; Xu Ke-Wei

    2005-01-01

    X-ray diffraction is used extensively to determine the residual stress in bulk or thin film materials on the assumptions that the material is composed of fine crystals with random orientation and the stress state is biaxial and homogeneous through the x-ray penetrating region. The stress is calculated from the gradient of ε~ sin2 ψ linear relation. But the method cannot be used in textured films due to nonlinear relation. In this paper, a novel method is proposed for measuring the multiaxial stresses in cubic films with any [hkl] fibre texture. As an example, a detailed analysis is given for measuring three-dimensional stresses in FCC films with [111] fibre texture.

  14. High temperature ferromagnetism in cubic Mn-doped ZrO{sub 2} thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Nguyen Hoa, E-mail: nguyenhong@snu.ac.kr [Nanomagnetism Laboratory, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Park, Chul-Kwon; Raghavender, A.T. [Nanomagnetism Laboratory, Department of Physics and Astronomy, Seoul National University, Seoul 151-747 (Korea, Republic of); Ruyter, Antoine [Laboratoire GREMAN, UMR 7347 CNRS - Universite F. Rabelais, Parc de Grandmont, 37200 Tours (France); Chikoidze, Ekaterina; Dumont, Yves [Laboratoire GEMaC, UMR 8635 Universite de Versailles St Quentin en Yvelines - CNRS, 45, Av. des Etats-Unis, 78035 Versailles Cedex (France)

    2012-09-15

    Theory has predicted that high temperature ferromagnetism (FM) should be found in cubic fake-diamonds, Mn-doped ZrO{sub 2}. Experimentally, it is shown that Mn-doped ZrO{sub 2} ceramics are not ferromagnetic, but the nanosized Mn-doped ZrO{sub 2} thin films grown on LaAlO{sub 3} substrates can be ferromagnets with T{sub C} above 400 K. The largest saturated magnetic moment (M{sub s}) is huge as of about 230 emu/cm{sup 3} for the Mn{sub 0.05}Zr{sub 0.95}O{sub 2} films, and it decreases as the Mn content increases. The intrinsic FM is strongly associated with the cubic structure of Mn-doped ZrO{sub 2}, and the Mn-Mn interactions via oxygen intermediates are important. No electrical conductivity is observed. Mn-doped ZrO{sub 2} thin films can be truly considered as excellent candidates for spintronic applications. - Highlights: Black-Right-Pointing-Pointer Mn-doped ZrO2 thin films can be ferromagnetic above room temperature. Black-Right-Pointing-Pointer Huge magnetic moment of 13.8 {mu}{sub B} per Mn is found in the sampledoping with 5% of Mn. Black-Right-Pointing-Pointer Magnetic force measurements confirm intrinsic ferromagnetism. Black-Right-Pointing-Pointer Important feedback to the theoretical work. Black-Right-Pointing-Pointer Good candidates for spintronics applications.

  15. Research on the piezoelectric response of cubic and hexagonal boron nitride films

    Institute of Scientific and Technical Information of China (English)

    CHEN Xi-ming; SUN Lian-jie; YANG Bao-he; GUO Yan; WU Xiao-guo

    2012-01-01

    Boron nitride (BN) films for high-frequency surface acoustic wave (SAW) devices are deposited on Ti/A(l)/Si(111) wafers byradio frequency (RF) magnetron sputtering.The structure of BN films is investigated by Fourier transform infrared (FTIR)spectroscopy and X-ray diffraction (XRD) spectra,and the surface morphology and piezoelectric properties of BN films are characterized by atomic force microscopy (AFM).The results show that when the flow ratio of nitrogen and argon is 2∶18,the cubic BN (c-BN) film is deposited with high purity and c-axis orientation,and when the flow ratio of nitrogen and argon is 4∶20,the hexagonal BN (h-BN) film is deposited with high c-axis orientation.Both particles are uniform and compact,and the roughnesses are 1.5 nm and 2.29 nm,respectively.The h-BN films have better piezoelectric response and distribution than the c-BN films.

  16. Electrochemical properties and applications of nanocrystalline, microcrystalline, and epitaxial cubic silicon carbide films.

    Science.gov (United States)

    Zhuang, Hao; Yang, Nianjun; Zhang, Lei; Fuchs, Regina; Jiang, Xin

    2015-05-27

    Microstructures of the materials (e.g., crystallinitiy, defects, and composition, etc.) determine their properties, which eventually lead to their diverse applications. In this contribution, the properties, especially the electrochemical properties, of cubic silicon carbide (3C-SiC) films have been engineered by controlling their microstructures. By manipulating the deposition conditions, nanocrystalline, microcrystalline and epitaxial (001) 3C-SiC films are obtained with varied properties. The epitaxial 3C-SiC film presents the lowest double-layer capacitance and the highest reversibility of redox probes, because of its perfect (001) orientation and high phase purity. The highest double-layer capacitance and the lowest reversibility of redox probes have been realized on the nanocrystalline 3C-SiC film. Those are ascribed to its high amount of grain boundaries, amorphous phases and large diversity in its crystal size. Based on their diverse properties, the electrochemical performances of 3C-SiC films are evaluated in two kinds of potential applications, namely an electrochemical capacitor using a nanocrystalline film and an electrochemical dopamine sensor using the epitaxial 3C-SiC film. The nanocrystalline 3C-SiC film shows not only a high double layer capacitance (43-70 μF/cm(2)) but also a long-term stability of its capacitance. The epitaxial 3C-SiC film shows a low detection limit toward dopamine, which is one to 2 orders of magnitude lower than its normal concentration in tissue. Therefore, 3C-SiC film is a novel but designable material for different emerging electrochemical applications such as energy storage, biomedical/chemical sensors, environmental pollutant detectors, and so on.

  17. Tuning the effective band gap and finding the optimal growth condition of InN thin films on GaN/sapphire substrates by plasma assisted molecular beam epitaxy technique

    Science.gov (United States)

    Ghosh, Kankat; Rathore, Jaswant Singh; Laha, Apurba

    2017-01-01

    InN thin films are grown on GaN/sapphire substrates with varying the nitrogen plasma power in plasma assisted molecular beam epitaxy (PA-MBE) system. In order to evaluate the effect of nitrogen plasma power on the different properties of the InN films, several characterization viz. x-ray diffraction, atomic force microscopy, photoluminescence measurement, infra-red spectroscopy and Hall measurement were performed. Two interesting phenomena observed from the measurements are described in this paper. Firstly, it is found from both the photoluminescence and infrared spectroscopy that only by varying the nitrogen plasma power (thus the III/V ratio), one can fine tune the optical absorption edge, i.e., the effective band gap of InN from ∼0.72 eV to ∼ 0.77 eV. Secondly, it is inferred that the film grown with stoichiometric condition (III/V ∼ 1) exhibits the best structural and electrical properties.

  18. In situ infrared spectroscopic study of cubic boron nitride thin film delamination

    Institute of Scientific and Technical Information of China (English)

    Yang Hang-Sheng; Zhang Jian-Ying; Nie An-Min; Zhang Xiao-Bin

    2008-01-01

    This paper investigates the procedure of cubic boron nitride(cBN)thin film delamination by Fourier-transform infrared(IR)spectroscopy.It finds that the apparent IR absorption peak area near 1380 cm-1 and 1073 cm-1 attributed to the B-N stretching vibration of sp2-bonded BN and the transverse optical phonon of cBN,respectively,increased up to 195% and 175% of the original peak area after film delamination induced compressive stress relaxation.The increase of IR absorption of sp2-bonded BN is found to be non-linear and hysteretic to film delamination,which suggests that the relaxation of the turbostratic BN(tBN)layer from the compressed condition is also hysteretic to film delamination.Moreover,cross-sectional transmission electron microscopic observations revealed that cBN film delamination is possible from near the aBN(amorphons BN)/tBN interface at least for films prepared by plasma-enhanced chemical vapour deposition.

  19. Epitaxial Cubic Ce2O3 Films via Ce-CeO2 Interfacial Reaction.

    Science.gov (United States)

    Stetsovych, Vitalii; Pagliuca, Federico; Dvořák, Filip; Duchoň, Tomáš; Vorokhta, Mykhailo; Aulická, Marie; Lachnitt, Jan; Schernich, Stefan; Matolínová, Iva; Veltruská, Kateřina; Skála, Tomáš; Mazur, Daniel; Mysliveček, Josef; Libuda, Jörg; Matolín, Vladimír

    2013-03-21

    Thin films of reduced ceria supported on metals are often applied as substrates in model studies of the chemical reactivity of ceria based catalysts. Of special interest are the properties of oxygen vacancies in ceria. However, thin films of ceria prepared by established methods become increasingly disordered as the concentration of vacancies increases. Here, we propose an alternative method for preparing ordered reduced ceria films based on the physical vapor deposition and interfacial reaction of Ce with CeO2 films. The method yields bulk-truncated layers of cubic c-Ce2O3. Compared to CeO2 these layers contain 25% of perfectly ordered vacancies in the surface and subsurface allowing well-defined measurements of the properties of ceria in the limit of extreme reduction. Experimentally, c-Ce2O3(111) layers are easily identified by a characteristic 4 × 4 surface reconstruction with respect to CeO2(111). In addition, c-Ce2O3 layers represent an experimental realization of a normally unstable polymorph of Ce2O3. During interfacial reaction, c-Ce2O3 nucleates on the interface between CeO2 buffer and Ce overlayer and is further stabilized most likely by the tetragonal distortion of the ceria layers on Cu. The characteristic kinetics of the metal-oxide interfacial reactions may represent a vehicle for making other metastable oxide structures experimentally available.

  20. The physical properties of cubic plasma-enhanced atomic layer deposition TaN films

    Science.gov (United States)

    Kim, H.; Lavoie, C.; Copel, M.; Narayanan, V.; Park, D.-G.; Rossnagel, S. M.

    2004-05-01

    Plasma-enhanced atomic layer deposition (PE-ALD) is a promising technique to produce high quality metal and nitride thin films at low growth temperature. In this study, very thin (<10 nm) low resistivity (350 μΩ cm) cubic TaN Cu diffusion barrier were deposited by PE-ALD from TaCl5 and a plasma of both hydrogen and nitrogen. The physical properties of TaN thin films including microstructure, conformality, roughness, and thermal stability were investigated by various analytical techniques including x-ray diffraction, medium energy ion scattering, and transmission electron microscopy. The Cu diffusion barrier properties of PE-ALD TaN thin films were studied using synchrotron x-ray diffraction, optical scattering, and sheet resistance measurements during thermal annealing of the test structures. The barrier failure temperatures were obtained as a function of film thickness and compared with those of PE-ALD Ta, physical vapor deposition (PVD) Ta, and PVD TaN. A diffusion kinetics analysis showed that the microstructure of the barrier materials is one of the most critical factors for Cu diffusion barrier performance.

  1. Effect of post-deposition annealing on the growth and properties of cubic SnS films

    Science.gov (United States)

    Chalapathi, U.; Poornaprakash, B.; Park, Si-Hyun

    2017-03-01

    We report a detailed investigation of the effect of post-deposition annealing on the growth and physical properties of chemically grown cubic SnS films. Chemically deposited cubic SnS films were subjected to annealing in a graphite box with loaded elemental sulfur under N2 at 150-350 °C for 10, 30, and 60 min in order to understand the grain growth and morphology of the films. Films annealed at 150-250 °C for 10 min showed improved grain size and a more uniform grain morphology. Films annealed at 150-250 °C for 30 and 60 min showed a decrease in the grain size and non-uniform grain morphology for the cubic SnS phase. Films annealed at 300 and 350 °C for 10 min revealed the formation of minor secondary phase SnS2, and the grain morphology changed from round shape to flake-like. Longer annealing at 300 and 350 °C improved the extent of the SnS2 phase, and it was found to be the dominant phase after annealing at 350 °C for 60 min. The direct optical band gap of SnS films is 1.75-1.67 eV, depending on the annealing temperature and time. The films exhibited p-type electrical conductivity. The films annealed at 250 °C for 10 min showed a higher hole mobility of 77.7 cm2V-1s-1. Thus, lower annealing temperatures and shorter annealing times are favorable conditions to produce high-quality cubic SnS films.

  2. 氮化时间对RF-MBE法生长InN薄膜晶体结构的影响%Influence of Nitridation Time on the RF-MBE Growth of InN Films Crystalline Structure

    Institute of Scientific and Technical Information of China (English)

    高芳亮; 管云芳; 李国强

    2013-01-01

    采用射频等离子体分子束外延(RF-MBE)技术在蓝宝石(Al2O3)衬底上外延生长了InN薄膜,在生长之前对其进行不同时间的氮化处理.通过扫描电子显微镜(SEM)和X射线衍射(XRD)对薄膜的形貌和结构进行了表征,发现氮化时间小于60 min时获得的InN薄膜的晶体结构为多晶且表面粗糙,而氮化时间为60 min及120 min时获得的InN薄膜为单晶结构,表面粗糙度有所下降.分析表明,氮化时间对InN薄膜的晶体结构有很重要的影响.%InN thin films with different nitridation time were grown by radio frequency plasma molecular beam epitaxy (RF-MBE) on sapphire (A12O3) substrate. By means of SEM and X-ray diffraction scanning, InN thin films obtained by nitridation time of less than 60 min present polycrystalline structure and rough surface morphology, while InN thin films obtained by nitridation time of 60 and 120 min have single crystal structure and less rough surface morphology. It shows that the nitridation time plays an important role in the formation of the InN crystal structure.

  3. Superconductivity in MBE grown InN

    Energy Technology Data Exchange (ETDEWEB)

    Gunes, M.; Balkan, N. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, CO4 3SQ, Colchester (United Kingdom); Tiras, E.; Ardali, S. [Department of Physics, Faculty of Science, Anadolu University, Yunus Emre Campus, 26470, Eskisehir (Turkey); Ajagunna, A.O.; Iliopoulos, E.; Georgakilas, A. [Microelectronics Research Group, IESL, FORTH and Physics Department, University of Crete, P.O. Box 1385, 71110 Heraklion, Crete (Greece)

    2011-05-15

    We present the experimental investigation of superconductivity in unintentionally doped MBE grown InN samples with various InN film thicknesses. A significant change in resistivity was observed at 3.82 K, for an 1080 nm InN layer with carrier concentration n{sub 3D}=1.185x10{sup 19} cm{sup -3}. However, no significant resistance change was observed in the case of InN samples with carrier density of 1.024x10{sup 19} cm{sup -3}, 1.38x10{sup 19} cm{sup -3}, and thicknesses of 2070 and 4700 nm, respectively. The carrier density of all investigated samples was within the range of values between the Mott transition (2x10{sup 17} cm{sup -3}) and the superconductivity to metal transition (7x10{sup 20} cm{sup -3}). We believe that at lower temperatures ({sup 3}He) which we cannot achieve with our set-up, the phase transition in other samples is likely to be observed. The origin of the observed anisotropic type-II superconductivity is discussed (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Thickness dependencies of structural and magnetic properties of cubic and tetragonal Heusler alloy bilayer films

    Science.gov (United States)

    Ranjbar, R.; Suzuki, K. Z.; Sugihara, A.; Ando, Y.; Miyazaki, T.; Mizukami, S.

    2017-07-01

    The thickness dependencies of the structural and magnetic properties for bilayers of cubic Co-based Heusler alloys (CCHAs: Co2FeAl (CFA), Co2FeSi (CFS), Co2MnAl (CMA), and Co2MnSi (CMS)) and D022-MnGa were investigated. Epitaxy of the B2 structure of CCHAs on a MnGa film was achieved; the smallest thickness with the B2 structure was found for 3-nm-thick CMS and CFS. The interfacial exchange coupling (Jex) was antiferromagnetic (AFM) for all of the CCHAs/MnGa bilayers except for unannealed CFA/MnGa samples. A critical thickness (tcrit) at which perpendicular magnetization appears of approximately 4-10 nm for the CMA/MnGa and CMS/MnGa bilayers was observed, whereas this thickness was 1-3 nm for the CFA/MnGa and CFS/MnGa films. The critical thickness for different CCHAs materials is discussed in terms of saturation magnetization (Ms) and the Jex .

  5. The Adhesion Improvement of Cubic Boron Nitride Film on High Speed Steel Substrate Implanted by Boron Element

    Institute of Scientific and Technical Information of China (English)

    CAI Zhi-hai; ZHANG Ping; TAN Jun

    2005-01-01

    Cubic boron nitride(c-BN) films were deposited on W6Mo5Cr4V2 high speed steel(HSS) substrate implanted with boron ion by RF-magnetron sputtering. The films were analyzed by the bending beam method, scratch test, XPS and AFM. The experimental results show that the implantation of boron atom can reduce the in ternal stress and improve the adhesion strength of the films. The critical load of scratch test rises to 27.45 N, compared to 1.75 N of c-BN film on the unimplanted HSS. The AFM shows that the surface of the c-BN film on the implanted HSS is low in roughness and small in grain size. Then the composition of the boron implanted layer was analyzed by the XPS. And the influence of the boron implanted layer on the internal stress and adhesion strength of c-BN films were investigated.

  6. Optical properties of InN studied by spectroscopic ellipsometry

    Science.gov (United States)

    Chunya, Ye; Wei, Lin; Jin, Zhou; Shuping, Li; Li, Chen; Heng, Li; Xiaoxuan, Wu; Songqing, Liu; Junyong, Kang

    2016-10-01

    With recently developed InN epitaxy via a controlling In bilayer, spectroscopic ellipsometry (SE) measurements had been carried out on the grown InN and the measured ellipsometric spectra were fitted with the Delta Psi2 software by using a suitable model and the dispersion rule. The thickness was measured by a scanning electron microscope (SEM). Insight into the film quality of InN and the lattice constant were gained by X-ray diffraction (XRD). By fitting the SE, the thickness of the InN film is consistent with that obtained by SEM cross-sectional thickness measurement. The optical bandgap of InN was put forward to be 1.05 eV, which conforms to the experimental results measured by the absorption spectrum and cathodoluminescence (CL). The refractive index and the extinction coefficient of interest were represented for InN, which is useful to design optoelectronic devices. Project supported by the State Key Development Program for Basic Research of China (No. 2012CB619301), the National High Technology Research and Development Program of China (No. 2014AA032608), the National Natural Science Foundation of China (Nos. 11204254, 11404271), and the Fundamental Research Funds for the Central Universities (Nos. 2012121014, 20720150027).

  7. Interplay of uniaxial and cubic anisotropy in epitaxial Fe thin films on MgO (001 substrate

    Directory of Open Access Journals (Sweden)

    Srijani Mallik

    2014-09-01

    Full Text Available Epitaxial Fe thin films were grown on annealed MgO(001 substrates at oblique incidence by DC magnetron sputtering. Due to the oblique growth configuration, uniaxial anisotropy was found to be superimposed on the expected four-fold cubic anisotropy. A detailed study of in-plane magnetic hysteresis for Fe on MgO thin films has been performed by Magneto Optic Kerr Effect (MOKE magnetometer. Both single step and double step loops have been observed depending on the angle between the applied field and easy axis i.e. along ⟨100⟩ direction. Domain images during magnetization reversal were captured by Kerr microscope. Domain images clearly evidence two successive and separate 90° domain wall (DW nucleation and motion along cubic easy cum uniaxial easy axis and cubic easy cum uniaxial hard axis, respectively. However, along cubic hard axis two 180° domain wall motion dominate the magnetization reversal process. In spite of having four-fold anisotropy it is essential to explain magnetization reversal mechanism in 0°< ϕ < 90° span as uniaxial anisotropy plays a major role in this system. Also it is shown that substrate rotation can suppress the effect of uniaxial anisotropy superimposed on four-fold anisotropy.

  8. Effects of low energy ion bombardment on the formation of cubic iron mononitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Prieto, Pilar [Departamento de Física Aplicada M-12, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Figuera, Juan de la [Instituto de Química-Física “Rocasolano”, CSIC, Serrano 119, 28006 Madrid (Spain); Sanz, José M. [Departamento de Física Aplicada M-12, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Marco, José F. [Instituto de Química-Física “Rocasolano”, CSIC, Serrano 119, 28006 Madrid (Spain)

    2013-07-31

    The formation of cubic nitrides with stoichiometry close to FeN obtained by ion assisted sputter deposition has been studied as a function of deposition parameters. In particular, we have explored the influence of the energy deposited by the assistant beam per deposited Fe atom to understand changes in composition, phase formation and nanocrystallinity of the films. An optimum N{sub 2}{sup +} ion energy and a J{sub N}/J{sub Fe} ratio (J{sub N} and J{sub Fe} represent the current density of N{sub 2}{sup +} ions and Fe atoms respectively) have been determined in order to obtain only iron mononitride phases. X-ray diffraction and Mössbauer spectroscopy revealed a phase evolution from ε-Fe{sub x(x≈2)}N to γ″ and γ‴-FeN as the N{sub 2}{sup +} ion energy and the J{sub N}/J{sub Fe} flux ratio increase. Pure nanocrystalline iron mononitride, with nitrogen content close to 50%, is obtained when J{sub N}/J{sub Fe} ratio reaches 5.9 and the N{sub 2}{sup +} ion energy is 63.4 eV. Further increments of N{sub 2}{sup +} energies and J{sub N}/J{sub Fe} values reverse this behavior and a phase evolution from γ″ and γ‴-FeN to ε-Fe{sub x(x≈2)}N is found. This behavior is attributed to energy damage and resputtering phenomena. It has also been found that γ‴-FeN phase coexists with γ″-FeN phase when the deposition is performed at room temperature. - Highlights: • We have grown iron nitride FeN{sub x(0.6} {sub ≤x≤1)} thin films by dual ion beam sputtering. • Effects of N{sub 2}{sup +} ion assistance in the formation of Fe mononitride phases are studied. • Nanocrystalline Fe mononitride with a composition FeN{sub x≈1} is obtained. • A phase evolution ε → γ‴ + γ″ → ε is observed as E{sub Fe} increases. • γ‴-FeN phase coexists with γ″-FeN at room temperature deposition conditions.

  9. Formation of InN nanoparticle and nanorod structures by nitrogen plasma annealing method

    Indian Academy of Sciences (India)

    Ajay Kumar Mann; Deepak Varandani; Bodh Raj Mehta; Lalit Kumar Malhotra; G Mangamma; A K Tyagi

    2008-06-01

    In the present study, a novel method involving nitrogen plasma annealing has been reported for preparing InN nanoparticle/nanorod structures and for improving the properties of InN nanoparticle layers. Plasma annealed structures have been characterized by X-ray diffraction, atomic force microscopy and photoluminescence spectroscopy techniques. InN nanoparticle layers have been prepared using activated reactive evaporation set up. It has been observed that there is a remarkable improvement in the conductivity and crystallinity of InN nanoparticle layers on annealing in nitrogen plasma. This has been attributed to the increase in the nitrogen content of the samples. Experiments involving plasma annealing of In nanorods deposited oxide template has also been carried out. It was found that on plasma treatment In nanorods get converted to mixed phase InN nanorods with hexagonal and cubic fractions.

  10. Optical properties of InN grown on Si(111) substrate

    Energy Technology Data Exchange (ETDEWEB)

    Sakalauskas, E.; Schley, P.; Raethel, J.; Klar, T.A.; Mueller, R.; Pezoldt, J.; Tonisch, K.; Goldhahn, R. [Institut fuer Mikro- und Nanotechnologien, Technische Universitaet Ilmenau (Germany); Grandal, J.; Sanchez-Garcia, M.A.; Calleja, E. [ISOM y Departamento de Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria (Spain); Vilalta-Clemente, A.; Ruterana, P. [CIMAP UMR 6252 CNRS-ENSICAEN-CEA-UCBN, Caen (France)

    2010-05-15

    A comprehensive characterization of the optical properties of wurtzite InN films grown by molecular beam epitaxy on Si(111) substrates is presented. Two types of films are investigated in this work: InN on AlN/Si(111) and InN on GaN/AlN/Si(111). Their properties are compared to a layer deposited on GaN/sapphire substrate. The dielectric function (DF) is obtained from spectroscopic ellipsometry (SE). The infrared studies yield the plasma frequency and thus the electron density, while the interband absorption is probed between 0.56 and 9.8 eV. For InN grown on Si(111) substrate, the absorption onset is slightly shifted to higher energies with respect to the InN film grown on GaN/sapphire which can be attributed to higher electron concentrations. Despite this, strongly pronounced optical transitions due to critical points of the band structure are found in the high-energy part of the DF. It emphasizes the already promising quality of the InN films on silicon. Band-gap renormalization (BGR), band filling, and strain are taken into account in order to estimate the intrinsic band gap of wurtzite InN. For the InN layers on silicon, we get a band gap between 0.66 and 0.685 eV. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  11. Exploiting the P L2,3 absorption edge for optics: spectroscopic and structural characterization of cubic boron phosphide thin films

    NARCIS (Netherlands)

    Huber, S.P.; Medvedev, V.V.; Meyer-Ilse, J.; Gullikson, E.; Padavala, B.; Edgar, J.H.; Sturm, J.M.; Kruijs, van de R.W.E.; Prendergast, D.; Bijkerk, F.

    2016-01-01

    The transmission of cubic boron phosphide (c-BP) thin films, prepared by chemical vapor deposition (CVD), was evaluated near the phosphorous L2,3 and boron K absorption edge. The c-BP films were analyzed with transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray ab

  12. Stable protein device platform based on pyridine dicarboxylic acid-bound cubic-nanostructured mesoporous titania films.

    Science.gov (United States)

    Kim, Hwajeong; Park, Sung Soo; Seo, Jooyeok; Ha, Chang-Sik; Moon, Cheil; Kim, Youngkyoo

    2013-08-14

    Here we shortly report a protein device platform that is extremely stable in a buffer condition similar to human bodies. The protein device platform was fabricated by covalently attaching cytochrome c (cyt c) protein molecules to organic coupler molecules (pyridine dicarboxylic acid, PDA) that were already covalently bound to an electron-transporting substrate. A cubic nanostructured mesoporous titania film was chosen as an electron-transporting substrate because of its large-sized cubic holes (∼7 nm) and highly crystalline cubic titania walls (∼0.4 nm lattice). Binding of PDA molecules to the mesoporous titania surface was achieved by esterification reaction between carboxylic acid groups (PDA) and hydroxyl groups (titania) in the presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) mediator, whereas the immobilization of cyt c to the PDA coupler was carried out by the EDC-mediated amidation reaction between carboxylic acid groups (PDA) and amine groups (cyt c). Results showed that the 2,4-position isomer among several PDAs exhibited the highest oxidation and reduction peak currents. The cyt c-immobilized PDA-bound titania substrates showed stable and durable electrochemical performances upon continuous current-voltage cycling for 240 times (the final current change was less than 3%) and could detect superoxide that is a core indicator for various diseases including cancers.

  13. Epitaxial growth of cubic Gd2O3 thin films on Ge substrates

    Science.gov (United States)

    Molle, A.; Wiemer, C.; Bhuiyan, M. D. N. K.; Tallarida, G.; Fanciulli, M.

    2008-03-01

    Gd2O3 thin films were grown on Ge (001) substrates by molecular beam epitaxy. The epitaxial character of the film is demonstrated by electron diffraction during the growth. The structural characterization of the films shows that the Gd2O3 forms a bixbyite polymorph with a (110) out-of-plane orientation. The formation of bixbyite structured Gd2O3 is discussed in terms of the atomic arrangement of the oxide planes on the Ge(001) surface.

  14. Growth of boron doped hydrogenated nanocrystalline cubic silicon carbide (3C-SiC) films by Hot Wire-CVD

    Energy Technology Data Exchange (ETDEWEB)

    Pawbake, Amit [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Mayabadi, Azam; Waykar, Ravindra; Kulkarni, Rupali; Jadhavar, Ashok [School of Energy Studies, Savitribai Phule Pune University, Pune 411 007 (India); Waman, Vaishali [Modern College of Arts, Science and Commerce, Shivajinagar, Pune 411 005 (India); Parmar, Jayesh [Tata Institute of Fundamental Research, Colaba, Mumbai 400 005 (India); Bhattacharyya, Somnath [Department of Metallurgical and Materials Engineering, IIT Madras, Chennai 600 036 (India); Ma, Yuan‐Ron [Department of Physics, National Dong Hwa University, Hualien 97401, Taiwan (China); Devan, Rupesh; Pathan, Habib [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India); Jadkar, Sandesh, E-mail: sandesh@physics.unipune.ac.in [Department of Physics, Savitribai Phule Pune University, Pune 411007 (India)

    2016-04-15

    Highlights: • Boron doped nc-3C-SiC films prepared by HW-CVD using SiH{sub 4}/CH{sub 4}/B{sub 2}H{sub 6}. • 3C-Si-C films have preferred orientation in (1 1 1) direction. • Introduction of boron into SiC matrix retard the crystallanity in the film structure. • Film large number of SiC nanocrystallites embedded in the a-Si matrix. • Band gap values, E{sub Tauc} and E{sub 04} (E{sub 04} > E{sub Tauc}) decreases with increase in B{sub 2}H{sub 6} flow rate. - Abstract: Boron doped nanocrystalline cubic silicon carbide (3C-SiC) films have been prepared by HW-CVD using silane (SiH{sub 4})/methane (CH{sub 4})/diborane (B{sub 2}H{sub 6}) gas mixture. The influence of boron doping on structural, optical, morphological and electrical properties have been investigated. The formation of 3C-SiC films have been confirmed by low angle XRD, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Fourier transform infra-red (FTIR) spectroscopy and high resolution-transmission electron microscopy (HR-TEM) analysis whereas effective boron doping in nc-3C-SiC have been confirmed by conductivity, charge carrier activation energy, and Hall measurements. Raman spectroscopy and HR-TEM analysis revealed that introduction of boron into the SiC matrix retards the crystallanity in the film structure. The field emission scanning electron microscopy (FE-SEM) and non contact atomic force microscopy (NC-AFM) results signify that 3C-SiC film contain well resolved, large number of silicon carbide (SiC) nanocrystallites embedded in the a-Si matrix having rms surface roughness ∼1.64 nm. Hydrogen content in doped films are found smaller than that of un-doped films. Optical band gap values, E{sub Tauc} and E{sub 04} decreases with increase in B{sub 2}H{sub 6} flow rate.

  15. Cubic-to-monoclinic phase transition during the epitaxial growth of crystalline Gd2O3 films on Ge(001) substrates

    Science.gov (United States)

    Molle, Alessandro; Wiemer, Claudia; Bhuiyan, Md. Nurul Kabir; Tallarida, Grazia; Fanciulli, Marco; Pavia, Giuseppe

    2007-05-01

    Thin crystalline films of Gd2O3 are grown on an atomically flat Ge(001) surface by molecular beam epitaxy and are characterized in situ by reflection high energy electron diffraction and x-ray photoelectron spectroscopy, and ex situ by x-ray diffraction (XRD), atomic force microscopy (AFM), and transmission electron microscopy. The first stage of the growth corresponds to a cubic (110) structure, with two equiprobable, 90° rotated, in-plane domains. Increasing the thickness of the films, a phase transition from cubic (110) to monoclinic (100) oriented crystallites is observed which keeps the in-plane domain rotation, as evidenced by XRD and AFM.

  16. Pure Cubic-Phase Hybrid Iodobismuthates AgBi2 I7 for Thin-Film Photovoltaics.

    Science.gov (United States)

    Kim, Younghoon; Yang, Zhenyu; Jain, Ankit; Voznyy, Oleksandr; Kim, Gi-Hwan; Liu, Min; Quan, Li Na; García de Arquer, F Pelayo; Comin, Riccardo; Fan, James Z; Sargent, Edward H

    2016-08-08

    Bismuth-based hybrid perovskites are candidates for lead-free and air-stable photovoltaics, but poor surface morphologies and a high band-gap energy have previously limited these hybrid perovskites. A new materials processing strategy to produce enhanced bismuth-based thin-film photovoltaic absorbers by incorporation of monovalent silver cations into iodobismuthates is presented. Solution-processed AgBi2 I7 thin films are prepared by spin-coating silver and bismuth precursors dissolved in n-butylamine and annealing under an N2 atmosphere. X-ray diffraction analysis reveals the pure cubic structure (Fd3m) with lattice parameters of a=b=c=12.223 Å. The resultant AgBi2 I7 thin films exhibit dense and pinhole-free surface morphologies with grains ranging in size from 200-800 nm and a low band gap of 1.87 eV suitable for photovoltaic applications. Initial studies produce solar power conversion efficiencies of 1.22 % and excellent stability over at least 10 days under ambient conditions.

  17. Tricontinuous Cubic Nanostructure and Pore Size Patterning in Mesostructured Silica Films Templated with Glycerol Monooleate.

    Science.gov (United States)

    Dunphy, Darren R; Garcia, Fred L; Kaehr, Bryan; Khripin, Constantine Y; Collord, Andrew D; Baca, Helen K; Tate, Michael P; Hillhouse, Hugh W; Strzalka, Joseph W; Jiang, Zhang; Wang, Jin; Brinker, C Jeffrey

    2011-04-26

    The fabrication of nanostructured films possessing tricontinuous minimal surface mesophases with well-defined framework and pore connectivity remains a difficult task. As a new route to these structures, we introduce glycerol monooleate (GMO) as a template for evaporation-induced self-assembly. As deposited, a nanostructured double gyroid phase is formed, as indicated by analysis of grazing-incidence small-angle x-ray scattering data. Removal of GMO by UV/O(3) treatment or acid extraction induces a phase change to a nanoporous body-centered structure which we tentatively identify as based on the IW-P surface. To improve film quality, we add a co-surfactant to the GMO in a mass ratio of 1:10; when this co-surfactant is cetyltrimethylammonium bromide, we find an unusually large pore size (8-12 nm) in acid extracted films, while UV/O(3) treated films yield pores of only ca. 4 nm. Using this pore size dependence on film processing procedure, we create a simple method for patterning pore size in nanoporous films, demonstrating spatially-defined size-selective molecular adsorption.

  18. Periodic Arrays of Film-Coupled Cubic Nanoantennas as Tunable Plasmonic Metasurfaces

    Directory of Open Access Journals (Sweden)

    Vassilios Yannopapas

    2015-03-01

    Full Text Available We show theoretically that a two-dimensional periodic array of metallic nanocubes in close proximity to a metallic film acts as a metasurface with tunable absorbance. The presence of a metallic film underneath the array of plasmonic nanocubes leads to an impedance matched plasmonic metasurface enhancing up to 4 times the absorbance of incident radiation, in the spectral region below 500 nm. The absorbance spectrum is weakly dependent on the angle of incidence and state of polarization of incident light a functionality which can find application in thermo-photovoltaics. Our calculations are based on a hybrid layer-multiple-scattering (hLMS method based on a discrete-dipole approximation (DDA/T-matrix point matching method.

  19. Influence of Different Interlayers on Growth Mode and Properties of InN by MOVPE

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ri-Qing; LIU Xiang-Lin; KANG Ting-Ting; HU Wei-Guo; YANG Shao-Yan; JIAO Chun-Mei; ZHU Qing-Sheng

    2008-01-01

    We grow InN epilayers on different interlayers by metal organic vapour phase epitaxy(MOVPE)method,and investigate the effect of interlayer on the properties and growth mode of InN films.Three InN samples were deposited on nitrided sapphire,low-temperature InN(LT-InN)and high-temperature GaN(HT-GaN),respectively.The InN layer grown directly on nitrided sapphire owns the narrowest x-ray diffraction rocking curve(XRC)width of 300 arcsec among the three samples,and demonstrates a two-dimensional(2D)step-flow-like lateral growth mode,which is much different from the three-dimensional(3D)pillar-like growth mode of LT-InN and HT-GaN buffered samples.It seems that mismatch tensile strain is helpful for the lateral epitaxy of InN film.whereas compressive strain promotes the vertical growth of InN films.

  20. Growth and characterization of {beta}-In N films on Mg O: the key role of a {beta}-Ga N buffer layer in growing cubic In N

    Energy Technology Data Exchange (ETDEWEB)

    Navarro C, H.; Perez C, M.; Rodriguez, A. G.; Lopez L, E.; Vidal, M. A. [Universidad Autonoma de San Luis Potosi, Coordinacion para la Innovacion y la Aplicacion de la Ciencia y la Tecnologia, Alvaro Obregon 64, 78000 San Luis Potosi (Mexico)

    2012-07-01

    Cubic In N samples were grown on Mg O (001) substrates by gas source molecular beam epitaxy. In general, we find that In N directly deposited onto the Mg O substrate results in polycrystalline or columnar films of hexagonal symmetry. We find that adequate conditions to grow the cubic phase of this compound require the growth of an initial cubic Ga N buffer interlayer ({beta}-t Ga N) on the Mg O surface. Subsequently, the growth conditions were optimized to obtain good photoluminescence (Pl) emission. The resultant In N growth is mostly cubic, with very small hexagonal inclusions, as confirmed by X-ray diffraction and scanning electron microscopy studies. Good crystalline quality requires that the samples to be grown under rich Indium metal flux. The cubic {beta}-t In N/Ga N/Mg O samples exhibit a high signal to noise ratio for Pl at low temperatures (20 K). The Pl is centered at O.75 eV and persist at room temperature. (Author)

  1. Epitaxial relationship of semipolar s-plane (1101) InN grown on r-plane sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Dimitrakopulos, G. P. [Department of Physics, Aristotle University of Thessaloniki, GR 541 26 Thessaloniki (Greece)

    2012-07-02

    The heteroepitaxy of semipolar s-plane (1101) InN grown directly on r-plane sapphire by plasma-assisted molecular beam epitaxy is studied using transmission electron microscopy techniques. The epitaxial relationship is determined to be (1101){sub InN} Parallel-To (1102){sub Al{sub 2O{sub 3}}}, [1120]{sub InN} Parallel-To [2021]{sub Al{sub 2O{sub 3}}}, [1102]{sub InN}{approx} Parallel-To [0221]{sub Al{sub 2O{sub 3}}}, which ensures a 0.7% misfit along [1120]{sub InN}. Two orientation variants are identified. Proposed geometrical factors contributing to the high density of basal stacking faults, partial dislocations, and sphalerite cubic pockets include the misfit accommodation and reduction, as well as the accommodation of lattice twist.

  2. Effect of Phase Purity on Dislocation Density of Pressurized-Reactor Metalorganic Vapor Phase Epitaxy Grown InN

    Science.gov (United States)

    Iwabuchi, Takuya; Liu, Yuhuai; Kimura, Takeshi; Zhang, Yuantao; Prasertsuk, Kiattiwut; Watanabe, Haruna; Usami, Noritaka; Katayama, Ryuji; Matsuoka, Takashi

    2012-04-01

    The effect of the metastable zincblende (ZB) InN inclusion in the stable wurtzite (WZ) InN on the threading dislocation densities (TDDs) of an InN film grown by pressurized-reactor metalorganic vapor phase epitaxy has been studied by X-ray diffraction measurements. InN films are directly grown on c-plane sapphire substrates with nitrided surfaces at 1600 Torr with the different growth temperature from 500 to 700 °C. Films including ZB-InN show the correlation between the ZB volume fraction and the edge component of TDDs, not the screw component of TDDs. This result can be crystallographically understood by a simple model explaining how the ZB structure is included, i.e., ZB domains existing side-by-side with WZ domains and twined ZB domains. This can be clearly observed by electron backscatter diffraction.

  3. Low-temperature self-limiting atomic layer deposition of wurtzite InN on Si(100

    Directory of Open Access Journals (Sweden)

    Ali Haider

    2016-04-01

    Full Text Available In this work, we report on self-limiting growth of InN thin films at substrate temperatures as low as 200 °C by hollow-cathode plasma-assisted atomic layer deposition (HCPA-ALD. The precursors used in growth experiments were trimethylindium (TMI and N2 plasma. Process parameters including TMI pulse time, N2 plasma exposure time, purge time, and deposition temperature have been optimized for self-limiting growth of InN with in ALD window. With the increase in exposure time of N2 plasma from 40 s to 100 s at 200 °C, growth rate showed a significant decrease from 1.60 to 0.64 Å/cycle. At 200 °C, growth rate saturated as 0.64 Å/cycle for TMI dose starting from 0.07 s. Structural, optical, and morphological characterization of InN were carried out in detail. X-ray diffraction measurements revealed the hexagonal wurtzite crystalline structure of the grown InN films. Refractive index of the InN film deposited at 200 °C was found to be 2.66 at 650 nm. 48 nm-thick InN films exhibited relatively smooth surfaces with Rms surface roughness values of 0.98 nm, while the film density was extracted as 6.30 g/cm3. X-ray photoelectron spectroscopy (XPS measurements depicted the peaks of indium, nitrogen, carbon, and oxygen on the film surface and quantitative information revealed that films are nearly stoichiometric with rather low impurity content. In3d and N1s high-resolution scans confirmed the presence of InN with peaks located at 443.5 and 396.8 eV, respectively. Transmission electron microscopy (TEM and selected area electron diffraction (SAED further confirmed the polycrystalline structure of InN thin films and elemental mapping revealed uniform distribution of indium and nitrogen along the scanned area of the InN film. Spectral absorption measurements exhibited an optical band edge around 1.9 eV. Our findings demonstrate that HCPA-ALD might be a promising technique to grow crystalline wurtzite InN thin films at low substrate temperatures.

  4. In induced reconstructions of Si(1 1 1) as superlattice matched epitaxial templates for InN growth

    Energy Technology Data Exchange (ETDEWEB)

    Kuyyalil, Jithesh [FOTON, UMR 6082, INSA, F-35708 Rennes (France); Tangi, Malleswararao [Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India); Shivaprasad, S.M., E-mail: smsprasad@jncasr.ac.in [Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur P.O., Bangalore 560064 (India)

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► A novel growth method to form InN at low growth temperatures. ► Use of Si reconstruction as a growth template for group III nitrides. ► Band gap variation of InN – Moss–Burstein shift – non-parabolic conduction band for InN. ► Super lattice matching epitaxy of metal induced reconstructions with III–V unit cell. -- Abstract: Indium induced surface reconstructions of Si(1 1 1)-7 × 7 are used as templates to grow high quality InN. We grow InN on Si(1 1 1)-7 × 7, Si(1 1 1)-4 × 1-In and Si(1 1 1)-1 × 1-In reconstructed surfaces and study the quality of the films formed using complementary characterization tools. InN grown on Si(1 1 1)-1 × 1-In reconstruction shows superior film quality with lowest band-edge emission having a narrow full width at half maximum, intense and narrow 0 0 0 2 X-ray diffraction, low surface roughness and carrier concentration an order lower than other samples. We attribute the high quality of the film formed at 300 °C to the integral matching of InN and super lattice dimensions, we also study the reasons for the band gap variation of InN in the literature. Present study demonstrates the proposed Superlattice Matched Epitaxy can be a general approach to grow good quality InN at much lower growth temperature on compatible In induced reconstructions of the Si surface.

  5. The competitive growth of cubic domains in Ti(1-x)AlxN films studied by diffraction anomalous near-edge structure spectroscopy.

    Science.gov (United States)

    Pinot, Y; Tuilier, M-H; Pac, M-J; Rousselot, C; Thiaudière, D

    2015-11-01

    Titanium and aluminium nitride films deposited by magnetron sputtering generally grow as columnar domains made of oriented nanocrystallites with cubic or hexagonal symmetry depending on Al content, which are embedded in more disordered grain boundaries. The substitution of Al atoms for Ti in the cubic lattice of the films improves their resistance to wear and oxidation, allowing their use as protective coatings. Ti K-edge X-ray absorption spectroscopy, which probes both crystallized and more disordered grain boundaries, and X-ray diffraction anomalous fine structure, which is sensitive to short- and long-range order within a given crystallized domain, are carried out on a set of Ti(1-x)AlxN films deposited by magnetron sputtering on Si substrates. Attention is paid to the shape of the pre-edge region, which is sensitive to the symmetry of the site occupied by Ti atoms, either octahedral in face-centred-cubic Ti-rich (TiN, Ti0.54Al0.46N) samples or tetrahedral in hexagonal-close-packed Al-rich (Ti0.32Al0.68N) films. In order to obain information on the titanium environment in the well crystallized areas, subtraction of the smooth part of the energy-dependent structure factor for the Bragg reflections is applied to the pre-edge region of the diffraction anomalous data in order to restore their spectroscopic appearance. A flat pre-edge is related to the typical octahedral environment of Ti atoms for cubic reflections. The difference observed between pre-edge spectra associated with face-centred-cubic 200 and 111 Bragg reflections of Ti0.54Al0.46N is assigned to Ti enrichment of 111 large well ordered domains compared with the more disordered 200 ones. The sharp peak observed in the spectrum recorded from the hexagonal 002 peak of Ti0.32Al0.68N can be regarded as a standard for the pure tetrahedral Ti environment in hexagonal-close-packed nitride.

  6. Hetero-epitaxial growth of the cubic single crystalline HfO 2 film as high k materials by pulsed laser ablation

    Science.gov (United States)

    Zhang, Xinqiang; Tu, Hailing; Wang, Xiaona; Xiong, Yuhua; Yang, Mengmeng; Wang, Lei; Du, Jun

    2010-10-01

    We report a hetero-epitaxial growth of cubic single crystalline HfO 2 film on Si substrates as high k materials by pulse laser ablation (PLA) at 820 °C. To eliminate the interfacial defects, the HfO 2 film has then been annealed at 900 °C for 5 min in N 2. Reflection high-energy electron diffraction (RHEED) results indicate orientation of the HfO 2 film on Si substrates corresponding to (∥( and [∥[. An interface layer has been revealed by high-resolution transmission electron microscope (HRTEM). Through capacitance-voltage ( C- V) and current-voltage ( I- V), it has been obtained that the leakage current of the HfO 2 gate insulator with dielectric constant of 26 is 5×10 -6 A/cm 2 at -1 V.

  7. Phenomenological theory of phase transitions in epitaxial BaxSr1-xTiO3 thin films on (111)-oriented cubic substrates

    Science.gov (United States)

    Shirokov, V. B.; Shakhovoy, R. A.; Razumnaya, A. G.; Yuzyuk, Yu. I.

    2015-07-01

    A phenomenological thermodynamic theory of BaxSr1-xTiO3 (BST-x) thin films epitaxially grown on (111)-oriented cubic substrates is developed using the Landau-Devonshire approach. The group-theoretical analysis of the low-symmetry phases was performed taking into account two order parameters: the polarization related to ionic shifts in polar zone-center F1u mode and the out-of-phase rotation of TiO6 octahedra corresponding to the R25 zone-boundary mode in the parent cubic phase P m 3 ¯ m . The eight-order thermodynamic potential for BST-x solid solutions was developed and analyzed. We constructed the "concentration-misfit strain" phase diagram for BST-x thin films at room temperature and found that polar rhombohedral R3m phase with the polarization normal to the substrate is stable for x > 0.72 and negative misfit strains, while ferroelectric monoclinic C2 and Cm phases with in-plane polarization are stable for much smaller x and positive or slightly negative misfit strains. We constructed the "temperature-misfit strain" phase diagrams for several concentrations (x = 1, 0.8, 0.6, 0.4, and 0.2). Systematic changes of the phase transition lines between the paraelectric and ferroelectric phases are discussed. The phase diagrams are useful for practical applications in thin-film engineering.

  8. Annealing behavior of hexagonal phase content in cubic GaN thin films grown on GaAs (001) by MOCVD

    Institute of Scientific and Technical Information of China (English)

    孙小玲; 杨辉; 王玉田; 李国华; 郑联喜; 李建斌; 徐大鹏; 王占国

    1999-01-01

    The annealing behavior of the hexagonal phase content in cubic GaN (c-GaN) thin films grown on GaAs (001) by MOCVD is reported. C-GaN thin films are grown on GaAs (001) substrates by metalorganic chemical vapor deposition (MOCVD). High temperature annealing is employed to treat the as-grown c-GaN thin films. The characterization of the c-GaN films is investigated by photoluminescence (PL) and Raman scattering spectroscopy. The change conditions of the hexagonal phase content in the metastable c-GaN are reported. There is a boundary layer existing in the c-GaN/GaAs film. When being annealed at high temperature, the intensity of the TOB and LOB phonon modes from the boundary layer weakens while that of the E2 phonon mode from the hexagonal phase increases. The content change of hexagonal phase has closer relationship with annealing temperature than with annealing time period.

  9. The Profile of Romanian Urban Inns

    Directory of Open Access Journals (Sweden)

    Monica Maria Coroș

    2016-11-01

    Full Text Available This paper is the third of a series of studies dedicated to tourist inns on the Romanian market. The previous papers focused on the identification of the tourist inns that currently function on the domestic market. Further, their potential as rural facilities was highlighted and their authenticity was discussed. The relevance of this research is linked to the fact that in the early 1990s tourist inns were excluded from the lists of lodging and food-serving facilities, ceasing to be officially ranked. Consequently, the inns’ owners were forced to reclassify as other accepted types or, even worse, to function in the shadow economy , without any official ranking. Moreover, the absence of inns on the market and the incoherent development of certain types of lodgings in Romania, have also led to the fact that entrepreneurs and tourists tend to be confused and, sometimes, not able to differentiate one type of accommodation unit from another. The main purpose of this research is to determine the extent to which urban inns can contribute to the authenticity of the Romanian tourism. From a methodological perspective, the paper relies on both official data (collected and processed based on the official Lists of Hospitality Facilities and on the information available on specialized websites. Thorough analyses have been run in order to identify the tourist structures pretending to be inns, to further categorize and discuss them according to various criteria. The main findings and conclusions of this paper reveal that inns have the potential to contribute to the authenticity of Romania’s hospitality industry .

  10. Extended metastable Al solubility in cubic VAlN by metal-ion bombardment during pulsed magnetron sputtering: film stress vs subplantation

    Science.gov (United States)

    Greczynski, G.; Mráz, S.; Ruess, H.; Hans, M.; Lu, J.; Hultman, L.; Schneider, J. M.

    2017-07-01

    Dynamic ion-recoil mixing of near-film-surface atomic layers is commonly used to increase the metastable solubility limit xmax in otherwise immiscible thin film systems during physical vapor deposition. Recently, Al subplantation achieved by irradiating the film growth surface with Al+ metal-ion flux was shown to result in an unprecedented xmax for VAlN, far above values obtained with gas ion irradiation. However, it is reasonable to assume that ion irradiation necessary for subplantation also leads to a compressive stress σ buildup. In order to separate the effects of Al+ bombardment on σ and xmax, and realize low-stress high-xmax nitride alloys, we grow metastable cubic V1-xAlxN (0.17 ≤ x ≤ 0.74) films using reactive magnetron sputtering under different ion irradiation conditions. Al and V targets are operated in Ar/N2 discharges employing (i) conventional DC (Ar+, N2+), (ii) hybrid High-power pulsed magnetron sputtering (HIPIMS)/DC processing with one type of metal ion present (Al+ or V+/V2+), and (iii) HIPIMS with concurrent Al+ and V+/V2+ fluxes. Comparison to the ab initio calculated Al solubility limit reveals that xmax = 0.55 achieved with V+/V2+ irradiation is entirely accountable for by stress. In contrast, Al+ fluxes provide a substantial increase in xmax to 0.63, which is 12% higher than that expected based on the stress-induced increase in metastable solubility. Correlative stress and atom probe tomography data confirm that the metastable Al solubility enhancement is enabled by Al+ subplantation. The here proposed processing strategy allows for growth of single-phase cubic nitride alloys with significantly increased Al concentrations embodying tremendous promise for substantial improvements in high temperature oxidation resistance and mitigates the risk of stress-induced adhesive or cohesive coating failure.

  11. Optical, structural and fluorescence properties of nanocrystalline cubic or monoclinic Eu:Lu{sub 2}O{sub 3} films prepared by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Martinet, C. [Laboratoire de Physico-Chimie des Materiaux Luminescents, CNRS-Universite Lyon1, 10, rue Andre-Marie Ampere, 69622 Villeurbanne Cedex (France)]. E-mail: martinet@pcml.univ-lyon1.fr; Pillonnet, A. [Laboratoire de Physico-Chimie des Materiaux Luminescents, CNRS-Universite Lyon1, 10, rue Andre-Marie Ampere, 69622 Villeurbanne Cedex (France); Lancok, J. [Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, 18221 Prague (Czech Republic); Garapon, C. [Laboratoire de Physico-Chimie des Materiaux Luminescents, CNRS-Universite Lyon1, 10, rue Andre-Marie Ampere, 69622 Villeurbanne Cedex (France)

    2007-10-15

    Eu{sup 3+}-doped lutetium oxide (Eu:Lu{sub 2}O{sub 3}) nanocrystalline films were grown on fused-silica substrates by pulsed laser deposition. Depending on deposition conditions (oxygen pressure, temperature and laser energy), the structure of the films changed from amorphous to crystalline and the cubic or monoclinic phases were obtained with varying preferential orientation and crystallite size. The monoclinic phase could be prepared for the first time at temperatures as low as 240 deg. C and in a narrow range of parameters. Although this phase has been previously reported for powder samples, it occurs only for high pressures and high temperatures preparation conditions. The refractive indices were measured by m-lines spectroscopy for both crystalline phases and their dispersion curve fitted by the Sellmeier expression. The specific Eu{sup 3+} fluorescence properties of the different phases, monoclinic and cubic, were registered and show modifications due to the disorder induced by the nanometric size of the crystallites, emphasised in particular by quasi-selective excitation in the charge transfer band.

  12. Friction behaviour of TiAlN films around cubic/hexagonal transition: A 2D grazing incidence X-ray diffraction and electron energy loss spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Pinot, Y. [Université de Haute Alsace, Laboratoire Physique et Mécanique Textiles (EA 4365), F-68093 Mulhouse (France); Pac, M.-J., E-mail: marie-jose.pac@uha.fr [Université de Haute Alsace, Laboratoire Physique et Mécanique Textiles (EA 4365), F-68093 Mulhouse (France); Henry, P. [Université de Haute Alsace, Laboratoire Physique et Mécanique Textiles (EA 4365), F-68093 Mulhouse (France); Rousselot, C. [Université de Franche-Comté, FEMTO-ST (UMR CNRS 6174), F-25211 Montbéliard (France); Odarchenko, Ya.I.; Ivanov, D.A. [Université de Haute Alsace, Institut de Science des Matériaux de Mulhouse (UMR 7361 CNRS), F-68093 Mulhouse (France); Ulhaq-Bouillet, C.; Ersen, O. [Université de Strasbourg, Institut de Physique et Chimie des Matériaux de Strasbourg (UMR CNRS 7504), F-67087 Strasbourg (France); Tuilier, M.-H. [Université de Haute Alsace, Laboratoire Physique et Mécanique Textiles (EA 4365), F-68093 Mulhouse (France)

    2015-02-27

    The properties at different scales of Ti{sub 1−x}Al{sub x}N films deposited by reactive magnetron sputtering from TiAl sintered (S) targets produced by powder metallurgy are compared with those of a set of films previously deposited in the same conditions from mosaic targets (M) made of pure Ti and Al metals. For compositions close to the hcp/fcc transition (around x = 0.6), the friction behaviour, growth directions and organization of crystallized domains are found to be sensitive to the type of target used. The resistance to crack creation is higher for Ti{sub 0.54}Al{sub 0.46}N (S) and Ti{sub 0.38}Al{sub 0.62}N (S) than for Ti{sub 0.50}Al{sub 0.50}N (M) and Ti{sub 0.32}Al{sub 0.68}N (M). From the measurement of mechanical properties, toughness, and wear volumes and from the observation of wear tracks, it is found that films prepared from sintered targets exhibit a better wear resistance. Grazing incidence X-ray diffraction and electron energy loss spectroscopy in Transmission Electronic Microscopy are used to investigate the long- and short-range orders within the films. The morphology of Ti{sub 0.54}Al{sub 0.46}N (S) film can be considered as an array of crystalline domains having reciprocal-space vectors 111 and 200 directed along the meridian but with random in-plane orientation. Ti{sub 0.38}Al{sub 0.62}N (S) Al-rich film presents a random orientation of the crystalline domains whereas Ti{sub 0.32}Al{sub 0.68}N (M) deposited from composite targets exhibits a well-oriented fibrillar structure. The N K-edge Electron Energy Loss Near Edge Spectra are discussed with previous results of Extended X-ray Absorption Fine Structure Spectroscopy, which has evidenced different values of Al–N and Ti–N bond lengths, either octahedral (cubic-like) or tetrahedral (hexagonal-like) within Ti{sub 0.50}Al{sub 0.50}N (M) and Ti{sub 0.32}Al{sub 0.68}N (M) films. For similar compositions, films deposited from sintered alloys contain more nitrogen atoms in octahedral cubic

  13. Growth and Characterization of Single Crystalline InN Grown on GaN by RF Sputtering for Robust Schottky Contacts

    Science.gov (United States)

    Harotoonian, Vache; Woodall, Jerry M.

    2016-12-01

    High-quality, single crystal wurtzite InN films were fabricated by radio-frequency magnetron reactive sputtering on GaN templates. The sputtered InN films in this study were about 100 nm thick. Atomic force microscopy analysis revealed the sputtered InN film had root-mean-square surface roughness of about 0.4 nm, which is comparable to the underlying GaN template. Coupled x-ray diffraction (XRD) measurements confirmed the (0001) preferred growth orientation and ω-rocking curve full-width-half-maximum (FWHM) = 0.85° for the symmetrical (0002) diffraction peak. The present InN film has the best crystal quality in terms of narrower FWHM of XRD rocking curve among reported sputtered InN thin films. In-plane and out-of-plane XRD measurements revealed a relaxed film. Room temperature Hall Effect measurements showed mobility of 110 cm2/V.s and electron concentration of 1-2 × 1020/cm3. The feasibility of utilizing a cost effective and productive method of sputtering to form robust Schottky contacts to GaN using InN, an immiscible and metallic-like semiconductor, was explored.

  14. The Children's Inn at NIH turns 25 | NIH MedlinePlus the Magazine

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: The Children's Inn The Children's Inn at NIH turns 25 Past Issues / ... home …" for all families! What to Expect at The Children's Inn The Children's Inn enhances opportunities for ...

  15. Electron transport in wurtzite InN

    Indian Academy of Sciences (India)

    F M Abou El-Ela; B M El-Assy

    2012-07-01

    Using ensemble Monte Carlo simulation technique, we have calculated the transport properties of InN such as the drift velocity, the drift mobility, the average electron, energy relaxation times and momentum relaxation times at high electric field. The scattering mechanisms included are polar optical phonon, ionized impurity, acoustic phonon and intervalley phonon. It is found that the maximum peak velocity only occurs when the electric field is increased to a value above a certain critical field. This critical field is strongly dependent on InN parameters. The steady-state transport parameters are in fair agreement with other recent calculations.

  16. Epitaxial growth of cubic Gd{sub 2}O{sub 3} thin films on Ge substrates

    Energy Technology Data Exchange (ETDEWEB)

    Molle, A; Wiemer, C; Bhuiyan, M D N K; Tallarida, G; Fanciulli, M [CNR-INFM, Laboratorio Nazionale MDM, via C. Olivetti 2, I-20041 Agrate Brianza (Italy)], E-mail: alessandro.molle@mdm.infm.it

    2008-03-15

    Gd{sub 2}O{sub 3} thin films were grown on Ge (001) substrates by molecular beam epitaxy. The epitaxial character of the film is demonstrated by electron diffraction during the growth. The structural characterization of the films shows that the Gd{sub 2}O{sub 3} forms a bixbyite polymorph with a (110) out-of-plane orientation. The formation of bixbyite structured Gd{sub 2}O{sub 3} is discussed in terms of the atomic arrangement of the oxide planes on the Ge(001) surface.

  17. Metastable nature of InN and In-rich InGaN alloys

    Science.gov (United States)

    Ivanov, S. V.; Shubina, T. V.; Komissarova, T. A.; Jmerik, V. N.

    2014-10-01

    The paper provides a thermodynamic insight into the metastable nature of InN and In-rich InGaN alloys, based on experimental studies of their plasma-assisted MBE growth and high-temperature decomposition, as well as on theoretical modeling of nitrogen vacancy behavior. This instability may easily result in occurrence of metallic In nanoparticles in the bulk of In(Ga)N films and in the vicinity of extended defects at high enough In content, which makes us consider this material as a metal-semiconductor composite. An overview of a wide set of experimental studies performed by us on the epitaxial films grown in many laboratories all around the world is given which proves an existence of such In nanoparticles in the films and shows how they affect optical and electrical properties of the epilayers. Possible applications of epitaxial InN layers for THz emitters and magnetic field sensors are discussed.

  18. Effect of interfacial lattice mismatch on bulk carrier concentration and band gap of InN

    Energy Technology Data Exchange (ETDEWEB)

    Kuyyalil, Jithesh [FOTON, UMR 6082, INSA, F-35708 Rennes (France); Tangi, Malleswararao; Shivaprasad, S. M. [Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore-560064 (India)

    2012-10-15

    The issue of ambiguous values of the band gap (0.6 to 2 eV) of InN thin film in literature has been addressed by a careful experiment. We have grown wurtzite InN films by PA-MBE simultaneously on differently modified c-plane sapphire substrates and characterized by complementary structural and chemical probes. Our studies discount Mie resonances caused by metallic In segregation at grain boundaries as the reason for low band gap values ( Almost-Equal-To 0.6 eV) and also the formation of Indium oxides and oxynitrides as the cause for high band gap value ( Almost-Equal-To 2.0 eV). It is observed that polycrystallinity arising from azimuthal miss-orientation of c-oriented wurtzite InN crystals increases the carrier concentration and the band gap values. We have reviewed the band gap, carrier concentration, and effective mass of InN in literature and our own measurements, which show that the Moss-Burstein relation with a non-parabolic conduction band accounts for the observed variation of band gap with carrier concentration.

  19. Transition from amorphous Fe to polycrystalline body-centred-cubic Fe in Gd/Fe and Dy/Fe multilayered thin films

    CERN Document Server

    Engl, K; Zweck, J

    2002-01-01

    Rare-earth/iron multilayered thin films were magnetron sputtered to investigate the thickness-dependent transition from amorphous iron to polycrystalline body-centred-cubic iron. To characterize this transition it is necessary to get information about the average short-range order (SRO) in the multilayers. A unique technique for measuring this SRO is calculating pair distribution functions (PDFs) from reduced intensity functions by using high-energy electron diffraction in a 300 kV transmission electron microscope. With a maximum resolution in the PDFs of 0.024 nm, this method offers a high sensitivity for the investigation of the SRO. Due to the planar probing characteristics of the experiment, one gets structure information on interfaces rather than from the bulk structure. A further advantage of this method is that no specimen preparation is necessary. Therefore preparation artefacts can be excluded.

  20. Magnetization and Coercivity in Ferromagnetic Films with Cubic Lattices%具有立方格点结构的铁磁薄膜的磁化强度和矫顽力

    Institute of Scientific and Technical Information of China (English)

    袁敏; 张君霞; 陈洪

    2005-01-01

    Using the variational cumulant expansion, the authors examine the magnetization and coercivity for spin1/2 ferromagnetic films of simple cubic, body-centered-cubic and face-centered-cubic lattices. It is shown that the magnetization and coercivity depend on the lattice structures as well as the temperature and the number of spin layers in the film.%使用变分累积展开法.计算了简单立方、体心立方、面心立方格点上自旋1/2的铁磁薄膜的磁化强度和矫玩力.显示磁化强度和矫顽力不仅依赖于温度和自旋层数,而且还依赖于格点结构.

  1. Suppression of ferromagnetism and observation of quantum well states in epitaxial thin films of the cubic ruthenate BaRuO3

    Science.gov (United States)

    Burganov, Bulat; Paik, Hanjong; Shen, Kyle; Schlom, Darrell

    The pseudocubic perovskite ruthenates ARuO3, where A is alkaline earth metal, are correlated materials where Hund's coupling drives correlations and leads to a low coherence scale, large renormalization, and formation of local moments. The ferromagnetic BaRuO3 has an ideal cubic structure and a larger bandwidth, compared to its GdFeO3-distorted counterparts, CaRuO3 and SrRuO3. In stark contrast to SrRuO3, which is a Fermi liquid below TC, BaRuO3 exhibits critical fluctuations near TC that are enhanced under hydrostatic pressure, which suppresses the Fermi liquid coherence scale and TC and drives a crossover into non-FL regime. Here we use ARPES to characterize the momentum-resolved electronic structure of strained ultrathin BaRuO3 films grown in situ by molecular beam epitaxy. The films on STO (001) are metallic down to 2 u.c. thickness and manifest clearly defined subbands of well-defined quasiparticles which arise due to quantum confinement effects. We observe that the bands are moderately renormalized compared to bare GGA bands and discover that the ferromagnetism can be suppressed in the atomically thin limit. We discuss our results on BaRuO3 in the context of our recent ARPES studies of the other perovskite ruthenates, SrRuO3 and CaRuO3.

  2. Impact of substrate nitridation on the growth of InN on In{sub 2}O{sub 3}(111) by plasma-assisted molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Cho, YongJin, E-mail: yjcho@alumni.nd.edu [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany); Sadofev, Sergey; Fernández-Garrido, Sergio [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany); Calarco, Raffaella, E-mail: calarco@pdi-berlin.de [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany); Riechert, Henning [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany); Galazka, Zbigniew; Uecker, Reinhard [Leibniz-Institut für Kristallzüchtung, Max-Born-Str. 2, 12489 Berlin (Germany); Brandt, Oliver [Paul-Drude-Institut für Festkörperelektronik, Hausvogteiplatz 5–7, 10117 Berlin (Germany)

    2016-04-30

    Highlights: • An in situ nitridation of the In{sub 2}O{sub 3}(111) substrate converts the surface of In{sub 2}O{sub 3}(111) to InN0001. • The morphology of InN films deposited on such nitridated In{sub 2}O{sub 3}(111) substrates is characteristic for growth by instable step-flow. • This different morphology is demonstrated to be a consequence of the different polarity of the InN films. • The polarity of InN films grown on In{sub 2}O{sub 3}(111) can be controlled. - Abstract: We study the growth of InN films on In{sub 2}O{sub 3}(111) substrates by plasma-assisted molecular beam epitaxy under N excess. InN films deposited directly on In{sub 2}O{sub 3}(111) exhibit a strongly faceted morphology. A nitridation step prior to growth is found to convert the In{sub 2}O{sub 3}(111) surface to InN{0001}. The morphology of InN films deposited on such nitridated In{sub 2}O{sub 3}(111) substrates is characteristic for growth by instable step-flow and is thus drastically different from the three-dimensional growth obtained without nitridation. We show that this change originates from the different polarity of the films: while InN films deposited directly on In{sub 2}O{sub 3}(111) are In-polar, they are N-polar when grown on the nitridated substrate.

  3. Cubic and hexagonal boron-nitride (c-BN/h-BN) thin films deposited in situ by r.f. magnetron sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.M.; Zambrano, G.; Baca, E.; Moran, O.; Prieto, P. [Departamento de Fisica, Universidad del Valle, A.A. 25360 Cali (Colombia); Bejarano, G. [Laboratorio de Recubrimientos Duros, CDT-ASTIN SENA, Cali (Colombia)

    2005-07-01

    Cubic boron-nitride (c-BN)/hexagonal boron nitride (h-BN) thin films were grown in situ on (100) oriented silicon substrates by r.f. (13.56 MHz) magnetron sputtering technique. In order to obtain the highest fraction of the c-BN phase, a negative d.c bias voltage, varying from 0 to -200 V was applied to the substrate during deposition. Another set of boron nitride thin films was deposited in situ on (100) oriented silicon substrates under r.f. bias voltage. The substrate holder was biased from 0 to -350 V by connecting such to an auxiliary r.f. generator (operated at 13.56 MHz). Films were characterized by Fourier Transformed Infrared Spectroscopy (FTIR) and Atomic Force Microscope (AFM). Well-defined peaks at 787 cm{sup -1}, 1100 cm{sup -1} and 1387 cm{sup -1}, corresponding to the 2{sub Au} (out-plane bending of B-N-B bond) h-BN vibration mode, the F2 (stretching) c-BN Transversal Optical (TO) mode and the E{sub 1u} (in-plane stretching of B-N bond) vibration mode of the h-BN, respectively, were observed in the FTIR spectra. A maximal fraction of the c-BN phase close to 85% was obtained under a bias voltage of -150 V at substrate temperature of 300 C and a total pressure of 4 x 10{sup -2} mbar. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Investigation of gas sensing properties of InN nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Madapu, Kishore K., E-mail: madupu@igcar.gov.in, E-mail: dhara@igcar.gov.in; Prasad, A. K.; Tyagi, A. K.; Dhara, S., E-mail: madupu@igcar.gov.in, E-mail: dhara@igcar.gov.in [Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102 (India)

    2015-06-24

    InN nanoparticles were grown by chemical vapor deposition technique using In{sub 2}O{sub 3} as precursor material. Raman spectroscopic studies show the presence of the wurtzite phase of as-grown InN. Size of the nanoparticles were in range from quantum dot (<8 nm) to larger sized particles (100 nm). We studied the gas sensing properties of InN nanoparticles with CH{sub 4} gas. Sensors substrates were fabricated with interdigitated Au electrodes. InN nanoparticles show high response towards CH{sub 4} with minimum detectable concentration of 50 ppm at 200 °C.

  5. Synthesis of [100] Wurtzite InN Nanowires and [011] Zinc-Blende InN Nanorods

    Institute of Scientific and Technical Information of China (English)

    NIE Chao; SHI Yi; ZHENG You-Dou; ZHANG Rong; XIE Zi-Li; XIU Xiang-Qiang; LIU Bin; FU De-Yi; LIU Qi-Jia; HAN Ping; GU Shu-Lin

    2008-01-01

    One-dimensional wurtzite InN nanowires and zincblende InN nanorods axe prepared by chemical vapour deposition (CVD) method on natural cleavage plane (110) of GaAs.The growth direction of InN nanowires is[100],with wurtzite structure.The stable crystal structure of InN is wurtzite (w-InN),zincblende structure (z-InN) is only reported for 2D InN crystals before.However,in this work,the zincblende InN nanorods[011]are synthesized and characterized. The SEM and TEM images show that every nanorod shapes a conical tip,which can be explained by the anisotropy of growth process and the theory of Ehrlich-Schwoebel barrier.

  6. InN nanorods prepared with CrN nanoislands by plasma-assisted molecular beam epitaxy

    Directory of Open Access Journals (Sweden)

    Young Sheng-Joue

    2011-01-01

    Full Text Available Abstract The authors report the influence of CrN nanoisland inserted on growth of baseball-bat InN nanorods by plasma-assisted molecular beam epitaxy under In-rich conditions. By inserting CrN nanoislands between AlN nucleation layer and the Si (111 substrate, it was found that we could reduce strain form Si by inserting CrN nanoisland, FWHM of the x-ray rocking curve measured from InN nanorods from 3,299 reduced to 2,115 arcsec. It is due to the larger strain from lattice miss-match of the film-like InN structure; however, the strain from lattice miss-match was obvious reduced owing to CrN nanoisland inserted. The TEM images confirmed the CrN structures and In droplets dissociation from InN, by these results, we can speculate the growth mechanism of baseball-bat-like InN nanorods.

  7. Investigation of III-V Nanowires by Plan-View Transmission Electron Microscopy: InN Case Study

    Science.gov (United States)

    Luna, Esperanza; Grandal, Javier; Gallardo, Eva; Calleja, José M.; Sánchez-García, Miguel Á.; Calleja, Enrique; Trampert, Achim

    2014-10-01

    We discuss observations of InN nanowires (NWs) by plan-view high-resolution transmission electron microscopy (TEM). The main difficulties arise from suitable methods available for plan-view specimen preparation. We explore different approaches and find that the best results are obtained using a refined preparation method based on the conventional procedure for plan-view TEM of thin films, specifically modified for the NW morphology. The fundamental aspects of such a preparation are the initial mechanical stabilization of the NWs and the minimization of the ion-milling process after dimpling the samples until perforation. The combined analysis by plan-view and cross-sectional TEM of the NWs allows determination of the degree of strain relaxation and reveals the formation of an unintentional shell layer (2-3 nm thick) around the InN NWs. The shell layer is composed of bcc-In2O3 nanocrystals with a preferred orientation with respect to the wurtzite InN: In2O3 [111] || InN [0001] and In2O3 || InN .

  8. Stability of Mg-incorporated InN surfaces: first-principles study

    Science.gov (United States)

    Akiyama, T.; Nakamura, K.; Ito, T.; Song, J.-H.; Freeman, A. J.

    2009-03-01

    InN films are attractive materials for electronic and optelectronic applications. The growth of InN eptitaxial films with n-type and p-type conductivity has traditionally been performed along the polar directionootnotetextR.E. Jones et al., Phys. Rev. Lett, 96, 125505 (2006), which may result in large polarization fields along the growth direction, reducing the radiative efficiency of quantum-well light emitters. To overcome this drawback, the growth along nonpolar orientation such as (1010) and (1120) planes and its p-type doping have been recently carried out. We have addressed this issue by performing first-principles pseudopotential calculations for Mg-incorporated InN surfaces in various orientations, including (1010) and (1120) as well as (0001) and (0001) surfacesootnotetextJ.-H. Song et al., Phys. Rev. Lett. 101, 106803 (2008). The calculated surface energies demonstrate that qualitative trends in the stability of Mg-incorporated surfaces agree with those on GaN surfaces ootnotetextJ.E. Northrup, Appl. Phys. Lett. 86, 122108 (2005), although several surface reconstructions different from those on GaN surfaces are obtained. The effects of growth conditions on p-type doping are also discussed.

  9. The Children's Inn at NIH Anniversary Key Messages | NIH MedlinePlus the Magazine

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: The Children's Inn The Children's Inn at NIH Past Issues / Summer 2014 ... Contents Anniversary Key Messages Playground and Park at The Children's Inn at NIH. Photo courtesy of Mahan ...

  10. Cubic III-nitrides: potential photonic materials

    Science.gov (United States)

    Onabe, K.; Sanorpim, S.; Kato, H.; Kakuda, M.; Nakamura, T.; Nakamura, K.; Kuboya, S.; Katayama, R.

    2011-01-01

    The growth and characterization of some cubic III-nitride films on suitable cubic substrates have been done, namely, c- GaN on GaAs by MOVPE, c-GaN and c-AlGaN on MgO by RF-MBE, and c-InN and c-InGaN (In-rich) on YSZ by RFMBE. This series of study has been much focused on the cubic-phase purity as dependent on the respective growth conditions and resulting electrical and optical properties. For c-GaN and c-InN films, a cubic-phase purity higher than 95% is attained in spite of the metastable nature of the cubic III-nitrides. However, for c-AlGaN and c-InGaN films, the cubic-phase purity is rapidly degraded with significant incorporation of the hexagonal phase through stacking faults on cubic {111} faces which may be exposed on the roughened growing or substrate surface. It has been shown that the electron mobilities in c-GaN and c-AlGaN films are much related to phase purity.

  11. 2nd INNS Conference on Big Data

    CERN Document Server

    Manolopoulos, Yannis; Iliadis, Lazaros; Roy, Asim; Vellasco, Marley

    2017-01-01

    The book offers a timely snapshot of neural network technologies as a significant component of big data analytics platforms. It promotes new advances and research directions in efficient and innovative algorithmic approaches to analyzing big data (e.g. deep networks, nature-inspired and brain-inspired algorithms); implementations on different computing platforms (e.g. neuromorphic, graphics processing units (GPUs), clouds, clusters); and big data analytics applications to solve real-world problems (e.g. weather prediction, transportation, energy management). The book, which reports on the second edition of the INNS Conference on Big Data, held on October 23–25, 2016, in Thessaloniki, Greece, depicts an interesting collaborative adventure of neural networks with big data and other learning technologies.

  12. Elimination of surface band bending on N-polar InN with thin GaN capping

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmík, J., E-mail: Jan.Kuzmik@savba.sk; Haščík, Š.; Kučera, M.; Kúdela, R.; Dobročka, E. [Institute of Electrical Engineering, Slovak Academy of Sciences, Dúbravska cesta 9, 841 04 Bratislava (Slovakia); Adikimenakis, A. [Microelectronics Research Group (MRG), IESL, FORTH, P.O. Box 1385, 71110 Heraklion, Crete (Greece); Mičušík, M. [Polymer Institute, Slovak Academy of Sciences, Dúbravska cesta 9, 845 41 Bratislava (Slovakia); Gregor, M.; Plecenik, A. [Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava, Mlynská dolina, 842 48 Bratislava (Slovakia); Georgakilas, A. [Microelectronics Research Group (MRG), IESL, FORTH, P.O. Box 1385, 71110 Heraklion, Greece and Department of Physics, University of Crete, 71203 Heraklion (Greece)

    2015-11-09

    0.5–1 μm thick InN (0001) films grown by molecular-beam epitaxy with N- or In-polarity are investigated for the presence of native oxide, surface energy band bending, and effects introduced by 2 to 4 monolayers of GaN capping. Ex situ angle-resolved x-ray photo-electron spectroscopy is used to construct near-surface (GaN)/InN energy profiles, which is combined with deconvolution of In3d signal to trace the presence of InN native oxide for different types of polarity and capping. Downwards surface energy band bending was observed on bare samples with native oxide, regardless of the polarity. It was found that the In-polar InN surface is most readily oxidized, however, with only slightly less band bending if compared with the N-polar sample. On the other hand, InN surface oxidation was effectively mitigated by GaN capping. Still, as confirmed by ultra-violet photo-electron spectroscopy and by energy band diagram calculations, thin GaN cap layer may provide negative piezoelectric polarization charge at the GaN/InN hetero-interface of the N-polar sample, in addition to the passivation effect. These effects raised the band diagram up by about 0.65 eV, reaching a flat-band profile.

  13. Investigation of III-V Nanowires by Plan-View Transmission Electron Microscopy: InN Case Study

    OpenAIRE

    Luna, E; Grandal, J.; Gallardo, E; Calleja, J.M.; Sánchez-García, M A; Calleja, E.; Trampert, A

    2013-01-01

    We discuss observations of InN nanowires (NWs) by plan-view high-resolution transmission electron microscopy (TEM). The main difficulties arise from suitable methods available for plan-view specimen preparation. We explore different approaches and find that the best results are obtained using a refined preparation method based on the conventional procedure for plan-view TEM of thin films, specifically modified for the NW morphology. The fundamental aspects of such a preparation are the initia...

  14. Optical characterization of free electron concentration in heteroepitaxial InN layers using Fourier transform infrared spectroscopy and a 2 Multiplication-Sign 2 transfer-matrix algebra

    Energy Technology Data Exchange (ETDEWEB)

    Katsidis, C. C. [Department of Materials Science and Technology, University of Crete, P.O. Box 2208, 71003 Heraklion-Crete (Greece); Ajagunna, A. O.; Georgakilas, A. [Microelectronics Research Group, IESL, FORTH, P.O. Box 1385, 71110 Heraklion-Crete (Greece); Physics Department, University of Crete, P.O. Box 2208, 71003 Heraklion-Crete (Greece)

    2013-02-21

    Fourier Transform Infrared (FTIR) reflectance spectroscopy has been implemented as a non-destructive, non-invasive, tool for the optical characterization of a set of c-plane InN single heteroepitaxial layers spanning a wide range of thicknesses (30-2000 nm). The c-plane (0001) InN epilayers were grown by plasma-assisted molecular beam epitaxy (PAMBE) on GaN(0001) buffer layers which had been grown on Al{sub 2}O{sub 3}(0001) substrates. It is shown that for arbitrary multilayers with homogeneous anisotropic layers having their principal axes coincident with the laboratory coordinates, a 2 Multiplication-Sign 2 matrix algebra based on a general transfer-matrix method (GTMM) is adequate to interpret their optical response. Analysis of optical reflectance in the far and mid infrared spectral range has been found capable to discriminate between the bulk, the surface and interface contributions of free carriers in the InN epilayers revealing the existence of electron accumulation layers with carrier concentrations in mid 10{sup 19} cm{sup -3} at both the InN surface and the InN/GaN interface. The spectra could be fitted with a three-layer model, determining the different electron concentration and mobility values of the bulk and of the surface and the interface electron accumulation layers in the InN films. The variation of these values with increasing InN thickness could be also sensitively detected by the optical measurements. The comparison between the optically determined drift mobility and the Hall mobility of the thickest sample reveals a value of r{sub H} = 1.49 for the Hall factor of InN at a carrier concentration of 1.11 Multiplication-Sign 10{sup 19} cm{sup -3} at 300 Degree-Sign {Kappa}.

  15. Terahertz Current Oscillation in Wurtzite InN

    Institute of Scientific and Technical Information of China (English)

    FENG Wei

    2012-01-01

    Current self-oscillation in doped n+nn+ wurtzite InN diodes driven by a dc electric field is theoretically investigated by solving the time-dependent drift-diffusion model. Current self-oscillation is associated with the negative differential mobility effect in the highly non-parabolic conduction band of InN. A detailed analysis of the dependence of current oscillations on the doping concentration and the applied electric Reid is presented. The current oscillation frequencies can reach up to the terahertz (THz) region. The n+nn+ InN self-oscillating diode may be a promising candidate for THz generation, and the calculation results may guide the design of the devices.%Current self-oscillation in doped n+nn+ wurtzite InN diodes driven by a dc electric field is theoretically investigated by solving the time-dependent drift-diffusion model.Current self-oscillation is associated with the negative differential mobility effect in the highly non-parabolic conduction band of InN.A detailed analysis of the dependence of current oscillations on the doping concentration and the applied electric field is presented.The current oscillation frequencies can reach up to the terahertz (THz) region.The n + nn+ InN self-oscillating diode may be a promising candidate for THz generation,and the calculation results may guide the design of the devices.

  16. Hole transport and photoluminescence in Mg-doped InN

    Energy Technology Data Exchange (ETDEWEB)

    Miller, N.; Ager III, J. W.; Smith III, H. M.; Mayer, M. A.; Yu, K. M.; Haller, E. E.; Walukiewicz, W.; Schaff, W. J.; Gallinat, C.; Koblmuller, G.; Speck, J. S.

    2010-03-24

    Hole conductivity and photoluminescence were studied in Mg-doped InN films grown by molecular beam epitaxy. Because surface electron accumulation interferes with carrier type determination by electrical measurements, the nature of the majority carriers in the bulk of the films was determined using thermopower measurements. Mg concentrations in a"window" from ca. 3 x 1017 to 1 x 1019 cm-3 produce hole-conducting, p-type films as evidenced by a positive Seebeck coecient. This conclusion is supported by electrolyte-based capacitance voltage measurements and by changes in the overall mobility observed by Hall effect, both of which are consistent with a change from surface accumulation on an n-type film to surface inversion on a p-type film. The observed Seebeck coefficients are understood in terms of a parallel conduction model with contributions from surface and bulk regions. In partially compensated films with Mg concentrations below the window region, two peaks are observed in photoluminescence at 672 meV and at 603 meV. They are attributed to band-to-band and band-to-acceptor transitions, respectively, and an acceptor binding energy of ~;;70 meV is deduced. In hole-conducting films with Mg concentrations in the window region, no photoluminescence is observed; this is attributed to electron trapping by deep states which are empty for Fermi levels close to the valence band edge.

  17. High-surface-quality nanocrystalline InN layers deposited on GaN templates by RF sputtering

    Energy Technology Data Exchange (ETDEWEB)

    Valdueza-Felip, Sirona; Naranjo, Fernando B.; Gonzalez-Herraez, Miguel [Grupo de Ingenieria Fotonica, Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala, Campus Universitario, 28871 Alcala de Henares, Madrid (Spain); Lahourcade, Lise; Monroy, Eva [Equipe mixte CEA-CNRS-UJF, Nanophysique et Semiconducteurs, INAC/SP2M/PSC, CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Fernandez, Susana [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, 28040 Madrid (Spain)

    2011-01-15

    We report a detailed study of the effect of deposition parameters on optical, structural, and morphological properties of InN films grown by reactive radio-frequency (RF) sputtering on GaN-on-sapphire templates in a pure nitrogen atmosphere. Deposition parameters under study are substrate temperature, RF power, and sputtering pressure. Wurtzite crystallographic structure with c-axis preferred growth orientation is confirmed by X-ray diffraction measurements. For the optimized deposition conditions, namely at a substrate temperature of 450 C and RF power of 30 W, InN films present a root-mean-square surface roughness as low as {proportional_to}0.4 nm, comparable to the underlying substrate. The apparent optical bandgap is estimated at 720 nm (1.7 eV) in all cases. However, the InN absorption band tail is strongly influenced by the sputtering pressure due to a change in the species of the plasma. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. A Practical Guide for X-Ray Diffraction Characterization of Ga(Al, In)N Alloys

    Institute of Scientific and Technical Information of China (English)

    ZHOU Sheng-Qiang; WU Ming-Fang; YAO Shu-De

    2005-01-01

    @@ Ga(In, Al)N alloys are used as an active layer or cladding layer in light emitting diodes and laser diodes. x-raydiffraction is extensively used to evaluate the crystalline quality, the chemical composition and the residual strain in Ga(Al,In)N thin films, which directly determine the emission wavelength and the device performance. Due to the minor mismatch in lattice parameters between Ga(Al, In)N alloy and a GaN virtual substrate, x-ray diffraction comes to a problem to separate the signal from Ga(Al,In)N alloy and GaN. We give a detailed comparison on different diffraction planes. In order to balance the intensity and peak separation between Ga(Al, In)N alloy and GaN, (0004) and (10-15) planes make the best choice for symmetric scan and asymmetric scan, respectively.

  19. Towards identification of localized donor states in InN

    Science.gov (United States)

    Plesiewicz, J.; Suski, T.; Dmowski, L.; Walukiewicz, W.; Yu, K. M.; Korman, A.; Ratajczak, R.; Stonert, A.; Lu, Hai; Schaff, W.

    2007-10-01

    Transport studies of as-grown and proton-irradiated n-InN have been performed aiming at verification of the nature of localized donor states resonant with the InN conduction band. These resonant donor states (RDS) show a clear contribution to the electrical conduction in low electron concentration InN epitaxial layers. We used proton irradiation to increase the number of incorporated native point defects of donor character in InN layers. Then, the performed studies of pressure dependence of the Hall electron concentration clearly show no increase in the number of RDS in samples exposed to irradiation in spite of the increase in the conducting electron concentration.

  20. The Children's Inn at NIH - Three Stories | NIH MedlinePlus the Magazine

    Science.gov (United States)

    ... of this page please turn JavaScript on. Feature: The Children's Inn The Children's Inn at NIH - Three Stories Past Issues / Summer 2014 Table of Contents Kristal Nemeroff—The Patient Kristal Nemeroff, age 2, at the Children's ...

  1. The Place Where Hope Lives: The Children's Inn Comforts Kids and Their Families

    Science.gov (United States)

    Skip Navigation Bar Home Current Issue Past Issues The Place Where Hope Lives: The Children's Inn Comforts Kids and Their Families Past ... Story by Melanie Modlin Photography by Veronika Lukasova The Children's Inn at NIH is a unique homeaway- ...

  2. Cubic Subalgebras and Cubic Closed Ideals of B-algebras

    Directory of Open Access Journals (Sweden)

    Tapan Senapati

    2015-06-01

    Full Text Available In this paper, the concept of cubic set to subalgebras, ideals and closed ideals of B-algebras are introduced. Relations among cubic subalgebras with cubic ideals and cubic closed ideals of B-algebras investigated. The homomorphic image and inverse image of cubic subalgebras, ideals are studied and some related properties are investigated. Also, the product of cubic B-algebras are investigated.

  3. Core levels, valence band structure and unoccupied states of clean InN surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Himmerlich, Marcel; Eisenhardt, Anja; Schaefer, Juergen A.; Krischok, Stefan [Institut fuer Physik and Institut fuer Mikro- und Nanotechnologien, TU Ilmenau (Germany)

    2008-07-01

    In this study we used a surface analytics system directly connected to a MBE growth module to study the surface properties of thin InN films. The samples were prepared by plasma assisted molecular beam epitaxy on GaN/Al{sub 2}O{sub 3}(0001) templates and exhibited a 2 x 2 reconstruction after growth. The prepared samples were analysed by photoelectron spectroscopy as well as electron energy loss spectroscopy (EELS). For the occupied states, a very good agreement to available theoretical calculations is found. Although, the valence band maximum is located at 1.6 eV, indicating strong downward band bending of {proportional_to}0.9 eV, photoemission is detected up to E{sub F}. This indicates that the Fermi level is pinned above the conduction band minimum, as recently predicted. The spin-orbit splitting of the In 4d level at 17.8 eV could be resolved using He II radiation. Furthermore, from the fine structure of the secondary electron cascade peak we extract the energy of different unoccupied states 0 eV to 9 eV above the vacuum level. These measurements enable us to identify features in the InN EELS spectra, with a loss energy larger than 16 eV, as interband transitions from the In 4d level.

  4. Coherent Fe-rich nano-scale perovskite oxide phase in epitaxial Sr2FeMoO6 films grown on cubic and scandate substrates

    Science.gov (United States)

    Deniz, Hakan; Preziosi, Daniele; Alexe, Marin; Hesse, Dietrich

    2017-01-01

    We report the growth of high-quality epitaxial Sr2FeMoO6 (SFMO) thin films on various unconventional oxide substrates, such as TbScO3, DyScO3, and Sr2Al0.3Ga0.7TaO6 (SAGT) as well as on the most commonly used one, SrTiO3 (STO), by pulsed laser deposition. The films were found to contain a foreign nano-scale phase coherently embedded inside the SFMO film matrix. Through energy dispersive X-ray spectroscopy and scanning transmission electron microscopy, we identified the foreign phase to be Sr2-xFe1+yMo1-yO6, an off-stoichiometric derivative of the SFMO compound with Fe rich content (y ≈ 0.6) and a fairly identical crystal structure to SFMO. The films on STO and SAGT exhibited very good magnetic properties with high Curie temperature values. All the samples have fairly good conducting behavior albeit the presence of a foreign phase. Despite the relatively large number of items of the foreign phase, there is no significant deterioration in the properties of the SFMO films. We discuss in detail how magneto-transport properties are affected by the foreign phase.

  5. Enhanced Performance of Dye-Sensitized Solar Cells with Nanostructure InN Compact Layer

    Science.gov (United States)

    Chen, Cheng-Chiang; Chen, Lung-Chien; Kuo, Shu-Jung

    2013-05-01

    This study presents a dye-sensitized solar cells (DSSCs) with a nanostructured InN compact layer (InN-CPL). The effect of a nanostructured InN-CPL in a DSSC structure prepared by radio frequency magnetron sputtering was examined. The InN-CPL effectively reduces the back reaction at the interface between the indium tin oxide (ITO) transparent conductive film and the electrolyte in the DSSC. DSSCs fabricated on ITO/InN-CPL/TiO2/D719 exhibited a short-circuit current density (JSC), open-circuit voltage (VOC), and power conversion efficiency (η) of 23.2 mA/cm2, 0.7 V, and 8.9%, respectively.

  6. Preparation of Cubic Boron Nitride Coating on WC-Co Substrate by Micro/Nanocrystalline Diamond Film Interlayer%基于微纳米金刚石过渡层的cBN刀具涂层制备

    Institute of Scientific and Technical Information of China (English)

    徐锋; 左敦稳; 张旭辉; 户海峰; 张骋; 王珉

    2013-01-01

    Cubic Boron Nitride(cBN) is a super-hard material, of which hardness is only less than diamond. But it has excellent chemical stability, especially no chemical reaction with ferrous materials. The cBN coating has irreplaceable function in the application of modern cutting tools. Research is carried out on the preparation of cBN coating on YG6 by micro/nanocrystalline diamond (M/NCD) film inter-layer. The micro/nanocrystalline diamond film is deposited in hot filament chemical vapor deposition system and cBN is deposited in radio frequency magnetron sputtering system. The scanning electron microscopy (SEM), Raman, atomic force microscopy(AFM), Fourier transferred infrared(FTIR) and in-denter are used to investigate the content, morphology and adhesion of the coating. The results show that the adhesion of cBN coating on WC-Co by micro/nanocrystalline diamond interlayer is much higher than that by nano diamond interlayer. The moderate bias voltage is important for the cBN film deposition in the magnetron sputtering process.%立方氮化硼(Cubic Boron Nitride,cBN)是仅次于金刚石的超硬材料,比金刚石具有更高的化学稳定性,可以胜任铁系金属的加工.本文在YG6硬质合金上基于微纳米金刚石过渡层开展cBN涂层的制备研究.本文在热丝化学气相沉积系统中制备微纳米金刚石过渡层(Micro/nanocrystalline diamond,M/NCD),在射频磁控溅射系统中制备cBN涂层,并对M/NCD与cBN涂层进行了成分、微观形貌与结合性能的研究.研究结果发现,在硬质合金基体上,M/NCD过渡层的结合性能明显优于NCD过渡层.磁控溅射制备cBN涂层过程中,存在适合cBN沉积的衬底偏压阈值,过高或过低的衬底偏压均不利于cBN含量的提高.

  7. Dependence of InN properties on MOCVD growth parameters

    Energy Technology Data Exchange (ETDEWEB)

    Tuna, Oe.; Giesen, C. [AIXTRON AG, Kaiserstr. 98, 52134 Herzogenrath (Germany); Behmenburg, H.; Kalisch, H.; Jansen, R.H. [Chair of Electromagnetic Theory, RWTH Aachen University, Kackertstr. 15-17, 52072 Aachen (Germany); Yablonskii, G.P. [Stepanov Institute of Physics, National Academy of Sciences of Belarus, Independence Ave. 68, Minsk 220072 (Belarus); Heuken, M. [AIXTRON AG, Kaiserstr. 98, 52134 Herzogenrath (Germany); Chair of Electromagnetic Theory, RWTH Aachen University, Kackertstr. 15-17, 52072 Aachen (Germany)

    2011-07-15

    In order to optimize the growth conditions, the effect of the most important growth parameters such as growth temperature, pressure and V/III ratio on MOCVD-grown InN was investigated. A series of samples were grown by changing the growth temperature from 500 C to 550 C at fixed growth pressure of 800 mbar and V/III ratio of 145000. An improvement of electrical properties with temperature increment was noted. The highest mobility of 1200 cm{sup 2}/Vs was achieved at 550 C with a bulk carrier concentration of 4.32 x 10{sup 18} cm{sup -3}. The effect of V/III ratio on In droplet formation and on carrier concentration was also studied. At fixed temperature of 520 C, reactor pressure of 200 mbar and at fixed NH{sub 3} flow of 3 slm, a rising TMIn flow from 1.2 {mu}mol/min to 2.0 {mu}mol/min results in a carrier concentration increment from 6.06 x 10{sup 18} cm{sup -3} to 1.33 x 10{sup 19} cm{sup -3}and a decrement of the mobility from 430 cm{sup 2}/Vs to 348 cm{sup 2}/Vs. X-ray diffraction measurements show that the intensity associated with In droplets on the surface is rising with increasing TMIn flow. The effect of reactor pressure on InN growth was also examined. A high sensitivity to growth pressure for crystalline quality of InN was observed. The full width at half maximum (FWHM) values of InN (0002) reflexes decreased with increasing reactor pressure. With increasing growth pressure above 200 mbar, FWHM of around 275 arcsec of InN (0002) was achieved. This FWHM value is the lowest reported in literature for MOCVD-grown InN so far. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Einsteinian cubic gravity

    Science.gov (United States)

    Bueno, Pablo; Cano, Pablo A.

    2016-11-01

    We drastically simplify the problem of linearizing a general higher-order theory of gravity. We reduce it to the evaluation of its Lagrangian on a particular Riemann tensor depending on two parameters, and the computation of two derivatives with respect to one of those parameters. We use our method to construct a D -dimensional cubic theory of gravity which satisfies the following properties: (1) it shares the spectrum of Einstein gravity, i.e., it only propagates a transverse and massless graviton on a maximally symmetric background; (2) it is defined in the same way in general dimensions; (3) it is neither trivial nor topological in four dimensions. Up to cubic order in curvature, the only previously known theories satisfying the first two requirements are the Lovelock ones. We show that, up to cubic order, there exists only one additional theory satisfying requirements (1) and (2). Interestingly, this theory is, along with Einstein gravity, the only one which also satisfies (3).

  9. Temperature switching of cavity modes in InN microcrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kazanov, D. R., E-mail: kazanovdr@gmail.com; Kaibyshev, V. H.; Davydov, V. Yu.; Smirnov, A. N.; Jmerik, V. N.; Kuznetsova, N. V.; Kopiev, P. S.; Ivanov, S. V.; Shubina, T. V. [Russian Academy of Sciences, Ioffe Physical–Technical Institute (Russian Federation)

    2015-11-15

    InN optical cavities supporting low-order whispering-gallery modes up to room temperature are formed by molecular-beam epitaxy on patterned substrates. The observed switching of the mode type with increasing temperature is explained in terms of changes in the optical parameters due to a shift of the absorption edge and modification of its shape. Modeling taking into account a variation in the refractive index reproduces the typical distributions of the electromagnetic-field intensity in the cavities.

  10. Real-Time Optical Monitoring and Simulations of Gas Phase Kinetics in InN Vapor Phase Epitaxy at High Pressure

    Science.gov (United States)

    Dietz, Nikolaus; Woods, Vincent; McCall, Sonya D.; Bachmann, Klaus J.

    2003-01-01

    Understanding the kinetics of nucleation and coalescence of heteroepitaxial thin films is a crucial step in controlling a chemical vapor deposition process, since it defines the perfection of the heteroepitaxial film both in terms of extended defect formation and chemical integrity of the interface. The initial nucleation process also defines the film quality during the later stages of film growth. The growth of emerging new materials heterostructures such as InN or In-rich Ga(x)In(1-x)N require deposition methods operating at higher vapor densities due to the high thermal decomposition pressure in these materials. High nitrogen pressure has been demonstrated to suppress thermal decomposition of InN, but has not been applied yet in chemical vapor deposition or etching experiments. Because of the difficulty with maintaining stochiometry at elevated temperature, current knowledge regarding thermodynamic data for InN, e.g., its melting point, temperature-dependent heat capacity, heat and entropy of formation are known with far less accuracy than for InP, InAs and InSb. Also, no information exists regarding the partial pressures of nitrogen and phosphorus along the liquidus surfaces of mixed-anion alloys of InN, of which the InN(x)P(1-x) system is the most interesting option. A miscibility gap is expected for InN(x)P(1-x) pseudobinary solidus compositions, but its extent is not established at this point by experimental studies under near equilibrium conditions. The extension of chemical vapor deposition to elevated pressure is also necessary for retaining stoichiometric single phase surface composition for materials that are characterized by large thermal decomposition pressures at optimum processing temperatures.

  11. Probing Nucleation Mechanism of Self-Catalyzed InN Nanostructures

    Directory of Open Access Journals (Sweden)

    Xu Guowei

    2009-01-01

    Full Text Available Abstract The nucleation and evolution of InN nanowires in a self-catalyzed growth process have been investigated to probe the microscopic growth mechanism of the self-catalysis and a model is proposed for high pressure growth window at ~760 Torr. In the initial stage of the growth, amorphous InN x microparticles of cone shape in liquid phase form with assistance of an InN x wetting layer on the substrate. InN crystallites form inside the cone and serve as the seeds for one-dimensional growth along the favorable [0001] orientation, resulting in single-crystalline InN nanowire bundles protruding out from the cones. An amorphous InN x sheath around the faucet tip serves as the interface between growing InN nanowires and the incoming vapors of indium and nitrogen and supports continuous growth of InN nanowires in a similar way to the oxide sheath in the oxide-assisted growth of other semiconductor nanowires. Other InN 1D nanostructures, such as belts and tubes, can be obtained by varying the InN crystallites nucleation and initiation process.

  12. Hexagonal-to-cubic phase transformation in composite thin films induced by FePt nanoparticles located at PS/PEO interfaces.

    Science.gov (United States)

    Aissou, Karim; Fleury, Guillaume; Pecastaings, Gilles; Alnasser, Thomas; Mornet, Stéphane; Goglio, Graziella; Hadziioannou, Georges

    2011-12-06

    The organization process of asymmetric poly(styrene-block-ethylene oxide) (PS-b-PEO) copolymer thin films blended with FePt nanoparticles is studied. In a first step, it is shown that FePt nanoparticles stabilized by oleic acid ligands are distributed within the PS matrix phase, whereas the same particles partially covered with short dopamine-terminated-methoxy poly(ethylene oxide) (mPEO-Dopa) are located at PS/PEO interfaces. The swelling of PS domains, induced by FePt_oleic acid nanoparticles during the solvent annealing process, results in formation of a disordered microstructure in comparison to the well-organized hexagonally close-packed (HCP) cylinder phase formed in the neat PS-b-PEO copolymer. The evolution of the microstructure of PS-b-PEO/FePt_mPEO-Dopa composite has been investigated for different solvent annealing treatments. Under high-humidity conditions during the vapor annealing process, the addition of FePt nanoparticles results in formation of spheres in the film split into terraces. The upper and lower terraces are occupied by spheres organized in an unusual square and HCP phases, respectively. Under low-humidity conditions, undulated PEO cylinders oriented parallel to substrate are formed in the presence of FePt nanoparticles. In this case, we observe that most of the nanoparticles accumulate within the core of topological defects, which induces a low nanoparticle concentration at the PS/PEO interfaces and so stabilizes an intermediate undulated cylinder phase.

  13. Guarded Cubical Type Theory

    DEFF Research Database (Denmark)

    Birkedal, Lars; Bizjak, Aleš; Clouston, Ranald;

    2016-01-01

    This paper improves the treatment of equality in guarded dependent type theory (GDTT), by combining it with cubical type theory (CTT). GDTT is an extensional type theory with guarded recursive types, which are useful for building models of program logics, and for programming and reasoning with co...

  14. Understanding and optimization of InN and high indium containing InGaN alloys by metal organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tuna, Oecal

    2013-07-18

    Among the III-nitride semiconductors (Ga,Al,In)N, InN is the most attractive one due to having the narrowest bandgap of 0.64 eV. The revision in the bandgap of InN makes the InGaN more important since one can cover the whole solar spectrum by only changing In composition in an InGaN layer. The comparison of quality of InN and InGaN layers grown using a metal organic chemical vapor deposition (MOCVD) and a molecular beam epitaxy (MBE) methods indicate that growth with MOCVD is the more challenging, again due to the high dissociation temperature of NH{sub 3} relative to the low decomposition temperature of InN (560-570 C). However, there is significant interest in developing an MOCVD process for InN and InGaN growth since MOCVD technology is the technology currently in use for commercial fabrication of group III nitride thin films. This thesis is therefore focused on a study of MOCVD growth of n- and p-type InN and In-rich InGaN films with the goal of providing new information on the influence of growth conditions on the film properties. Initially, a detailed investigation of MOCVD of InN is given. It is shown that MOCVD growth parameters (growth temperature and V/III ratio) have impacts on the layer properties such as In droplet formation on the surface as well as on its electrical and optical properties. PAS is employed for point defect analyzation. It is shown that In vacancies isolated by nitrogen vacancies are the dominant vacancy-type positron traps in InN. A decrease in the N vacancy concentration in InN is observed as a result of the growth temperature increase from 500 to 550 C. This is an indication of a reduction of N vacancy concentration by enhancing NH{sub 3} dissociation at high growth temperature. Results obtained from optical techniques (Raman and PL) are used to estimate the free carrier concentrations in InN. Electrical characterizations are also carried out using Hall measurements. Carrier concentration values obtained by these three techniques

  15. Optical properties of wurtzite InN and related alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sakalauskas, Egidijus

    2012-10-02

    In this work, optical properties of wurtzite structure InN and related ternary InGaN and AlInN, as well as quaternary AlInGaN alloys were investigated. The spectroscopic ellipsometer was used as the main characterization tool for the analysis of the optical properties. The InN samples grown on Si(111) substrates, as well as carbon doped InN samples were investigated from mid-infrared up to vacuum-ultraviolet spectral range. The electron concentration for InN samples were evaluated by solving a self-consistent problem that includes the IR-SE ellipsometry data analysis and the imaginary dielectric function around the band gap calculation. The intrinsic strain-free band-gap was estimated after taking into consideration a band-gap renormalization and Burstein-Moss shift, as well as a strain influence on the band gap. The k.p method was used to calculate the strain induced band-gap shift. From the analysis, it was shown that for the carbon doped InN samples the electron concentration increases linearly by increasing the CBr{sub 4} dopant pressure during the MBE growth process. The In-related alloys were investigated from near-infrared up to vacuum-ultraviolet spectral range. The analytical model of the dielectric function in the spectral range 1-10 eV was presented. From the fit of the analytical model to the experimental dielectric functions, the band gaps and high-energy inter-band transitions were estimated. The strain-free band-gap bowing parameters for ternary InGaN and AlInN alloys were obtained. It was demonstrated, that the bowing parameter for AlInN is composition dependent. With the knowledge of the bowing parameters of ternary alloys, it was possible to develop an empirical equation that allows to estimate the band gap for a quaternary AlInGaN alloy. All experimentally obtained band gaps are in good agreement with the ab-initio calculated values.

  16. Effects of growth temperature on nonpolar a-plane InN grown by molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Rajpalke, Mohana K.; Bhat, Thirumaleshwara N.; Krupanidhi, S.B. [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India); Roul, Basanta [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India); Central Research Laboratory, Bharat Electronics, Bangalore-560013 (India); Kumar, Mahesh [Materials Research Centre, Indian Institute of Science, Bangalore-560012 (India); Centre of Excellence in Information and Communication Technology, Indian Institute of Technology, Jodhpur-342011 (India); Sinha, Neeraj [Office of Principal Scientific Advisor, Government of India, New Delhi 110011 (India); Department of Materials Science, Gulbarga University, Gulbarga 585 106 (India); Jali, V.M. [Department of Physics, Gulbarga University, Gulbarga 585 106 (India)

    2014-04-15

    Nonpolar a-plane InN films were grown on r-plane sapphire substrate by plasma assisted molecular beam epitaxy with GaN underlayer. Effect of growth temperature on structural, morphological, and optical properties has been studied. The growth of nonpolar a-plane (1 1 -2 0) orientation was confirmed by high resolution X-ray diffraction study. The film grown at 500 C shows better crystallinity with the rocking curve FWHM 0.67 and 0.85 along [0 0 0 1] and [1 -1 0 0] directions, respectively. Scanning electron micrograph shows formation of Indium droplets at higher growth temperature. Room tem-perature absorption spectra show growth temperature dependent band gap variation from 0.74-0.81 eV, consistent with the expected Burstein-Moss effect. The rectifying behaviour of the I-V curve indicates the existence of Schottky barrier at the InN and GaN interface. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Convergence of valence bands for high thermoelectric performance for p-type InN

    Science.gov (United States)

    Li, Hai-Zhu; Li, Ruo-Ping; Liu, Jun-Hui; Huang, Ming-Ju

    2015-12-01

    Band engineering to converge the bands to achieve high valley degeneracy is one of effective approaches for designing ideal thermoelectric materials. Convergence of many valleys in the valence band may lead to a high Seebeck coefficient, and induce promising thermoelectric performance of p-type InN. In the current work, we have systematically investigated the electronic structure and thermoelectric performance of wurtzite InN by using the density functional theory combined with semiclassical Boltzmann transport theory. Form the results, it can be found that intrinsic InN has a large Seebeck coefficient (254 μV/K) and the largest value of ZeT is 0.77. The transport properties of p-type InN are better than that of n-type one at the optimum carrier concentration, which mainly due to the large Seebeck coefficient for p-type InN, although the electrical conductivity of n-type InN is larger than that of p-type one. We found that the larger Seebeck coefficient for p-type InN may originate from the large valley degeneracy in the valence band. Moreover, the low minimum lattice thermal conductivity for InN is one key factor to become a good thermoelectric material. Therefore, p-type InN could be a potential material for further applications in the thermoelectric area.

  18. Investigations on the structural and optical properties of sphere-shaped indium nitride (InN)

    Energy Technology Data Exchange (ETDEWEB)

    Bagavath, C.; Kumar, J. [Anna University, Crystal Growth Centre, Chennai, Tamil Nadu (India); Nasi, L. [IMEM-CNR, Parma (Italy)

    2017-04-15

    Indium nitride (InN) sphere-shaped micro crystals and nano crystals were made using sol-gel method. The crystalline size of the samples were calculated using X-ray diffraction, which were found to increase with the increase of nitridation temperature and time. High resolution-transmission electron microscopy images exhibited the distinct sphere shape of InN with different size of micro and nanometers. The calculated band gap of InN spheres using photo luminescence and UV-visible absorption spectra, was found to be 1.2 eV. Optical phonon modes of InN were determined from micro-Raman studies. (orig.)

  19. Spontaneous oscillations and pattern formation during chemical vapor deposition of metastable InN.

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, F.; Munkholm, A.; Wang, R.-V.; Streiffer, S. K.; Thompson, C.; Fuoss, P. H.; Latifi, K.; Elder, K. R.; Stephenson, G. B.; Philips Lumileds Lighting Co.; Northern Illinois Univ.; Oakland Univ.; Ohio Univ.; Intel Corp.

    2008-01-01

    We report observations of self-sustaining spatiotemporal chemical oscillations during metal-organic chemical vapor deposition of InN onto GaN. Under constant supply of vapor precursors trimethylindium and NH{sub 3}, the condensed-phase cycles between crystalline islands of InN and elemental In droplets. Propagating fronts between regions of InN and In occur with linear, circular, and spiral geometries. The results are described by a model in which the nitrogen activity produced by surface-catalyzed NH{sub 3} decomposition varies with the exposed surface areas of GaN, InN, and In.

  20. Spontaneous oscillations and waves during chemical vapor deposition of InN.

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, F.; Munkholm, A.; Wang, R.-V.; Streiffer, S. K.; Thompson, C.; Fuoss, P. H.; Latifi, K.; Elder, K. R.; Stephenson, G. B.; Philips Lumileds Lighting Co.; Northern Illinois Univ.; Oakland Univ.

    2008-08-22

    We report observations of self-sustaining spatiotemporal chemical oscillations during metal-organic chemical vapor deposition of InN onto GaN. Under constant supply of vapor precursors trimethylindium and NH{sub 3}, the condensed-phase cycles between crystalline islands of InN and elemental In droplets. Propagating fronts between regions of InN and In occur with linear, circular, and spiral geometries. The results are described by a model in which the nitrogen activity produced by surface-catalyzed NH{sub 3} decomposition varies with the exposed surface areas of GaN, InN, and In.

  1. Guarded Cubical Type Theory

    DEFF Research Database (Denmark)

    Birkedal, Lars; Bizjak, Aleš; Clouston, Ranald;

    2016-01-01

    This paper improves the treatment of equality in guarded dependent type theory (GDTT), by combining it with cubical type theory (CTT). GDTT is an extensional type theory with guarded recursive types, which are useful for building models of program logics, and for programming and reasoning...... with coinductive types. We wish to implement GDTT with decidable type-checking, while still supporting non-trivial equality proofs that reason about the extensions of guarded recursive constructions. CTT is a variation of Martin-L\\"of type theory in which the identity type is replaced by abstract paths between...... terms. CTT provides a computational interpretation of functional extensionality, is conjectured to have decidable type checking, and has an implemented type-checker. Our new type theory, called guarded cubical type theory, provides a computational interpretation of extensionality for guarded recursive...

  2. Guarded Cubical Type Theory

    DEFF Research Database (Denmark)

    Birkedal, Lars; Bizjak, Aleš; Clouston, Ranald;

    2016-01-01

    This paper improves the treatment of equality in guarded dependent type theory (GDTT), by combining it with cubical type theory (CTT). GDTT is an extensional type theory with guarded recursive types, which are useful for building models of program logics, and for programming and reasoning...... with coinductive types. We wish to implement GDTT with decidable type checking, while still supporting non-trivial equality proofs that reason about the extensions of guarded recursive constructions. CTT is a variation of Martin-L\\"of type theory in which the identity type is replaced by abstract paths between...... terms. CTT provides a computational interpretation of functional extensionality, enjoys canonicity for the natural numbers type, and is conjectured to support decidable type-checking. Our new type theory, guarded cubical type theory (GCTT), provides a computational interpretation of extensionality...

  3. Applying the INN model to the MaxClique problem

    Energy Technology Data Exchange (ETDEWEB)

    Grossman, T.

    1993-09-01

    Max-Clique is the problem of finding the largest clique in a given graph. It is not only NP-hard, but, as recent results suggest, even hard to approximate. Nevertheless it is still very important to develop and test practical algorithms that will find approximate solutions for the maximum clique problem on various graphs stemming from numerous applications. Indeed, many different types of algorithmic approaches are applied to that problem. Several neural networks and related algorithms were applied recently to combinatorial optimization problems in general and to the Max-Clique problem in particular. These neural nets are dynamical system which minimize a cost (or computational ``energy``) function that represents the optimization problem, the Max-Clique in our case. Therefore they all belong to the class of integer programming algorithms surveyed in the Pardalos and Xue review. The work presented here is a development and improvement of a neural network algorithm that was introduced recently. In the previous work, we have considered two Hopfield type neural networks, the INN and the HcN, and their application to the max-clique problem. In this paper, I concentrate on the INN network and present an improved version of the t-A algorithm that was introduced in. The rest of this paper is organized as follows: in section 2, I describe the INN model and how it implements a given graph. In section 3, it is characterized in terms of graph theory. In particular, the stable states of the network are mapped to the maximal cliques of its underling graph. In section 4, I present the t-Annealing algorithm and an improved version of it, the Adaptive t-Annealing. Several experiments done with these algorithms on benchmark graphs are reported in section 5, and the efficiency of the new algorithm is demonstrated. I conclude with a short discussion.

  4. Optical studies of cubic III-nitride structures

    OpenAIRE

    Powell, Ross E L

    2014-01-01

    The properties of cubic nitrides grown by molecular beam epitaxy (MBE) on GaAs (001) have been studied using optical and electrical techniques. The aim of these studies was the improvement of the growth techniques in order to improve the quality of grown nitrides intended for bulk substrate and optoelectronic device applications. We have also characterised hexagonal nanocolumn structures incorporating indium. Firstly, bulk films of cubic AlxGa1-xN with aluminium fractions (x) spanning the ...

  5. Understanding and optimization of InN and high indium containing InGaN alloys by metal organic chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Tuna, Oecal

    2013-07-18

    Among the III-nitride semiconductors (Ga,Al,In)N, InN is the most attractive one due to having the narrowest bandgap of 0.64 eV. The revision in the bandgap of InN makes the InGaN more important since one can cover the whole solar spectrum by only changing In composition in an InGaN layer. The comparison of quality of InN and InGaN layers grown using a metal organic chemical vapor deposition (MOCVD) and a molecular beam epitaxy (MBE) methods indicate that growth with MOCVD is the more challenging, again due to the high dissociation temperature of NH{sub 3} relative to the low decomposition temperature of InN (560-570 C). However, there is significant interest in developing an MOCVD process for InN and InGaN growth since MOCVD technology is the technology currently in use for commercial fabrication of group III nitride thin films. This thesis is therefore focused on a study of MOCVD growth of n- and p-type InN and In-rich InGaN films with the goal of providing new information on the influence of growth conditions on the film properties. Initially, a detailed investigation of MOCVD of InN is given. It is shown that MOCVD growth parameters (growth temperature and V/III ratio) have impacts on the layer properties such as In droplet formation on the surface as well as on its electrical and optical properties. PAS is employed for point defect analyzation. It is shown that In vacancies isolated by nitrogen vacancies are the dominant vacancy-type positron traps in InN. A decrease in the N vacancy concentration in InN is observed as a result of the growth temperature increase from 500 to 550 C. This is an indication of a reduction of N vacancy concentration by enhancing NH{sub 3} dissociation at high growth temperature. Results obtained from optical techniques (Raman and PL) are used to estimate the free carrier concentrations in InN. Electrical characterizations are also carried out using Hall measurements. Carrier concentration values obtained by these three techniques

  6. Determination of dislocation densities in InN

    Energy Technology Data Exchange (ETDEWEB)

    Ardali, Sukru; Tiras, Engin [Department of Physics, Faculty of Science, Anadolu University, Yunus Emre Campus, Eskisehir 26470 (Turkey); Gunes, Mustafa; Balkan, Naci [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Ajagunna, Adebowale Olufunso; Iliopoulos, Eleftherios; Georgakilas, Alexandros [Microelectronics Research Group, IESL, FORTH and Physics Department, University of Crete, P.O. Box 1385, 71110 Heraklion-Crete (Greece)

    2012-03-15

    The magneto-transport measurements, carried out at magnetic fields up to 11 T and in the temperature range between 1.8 K and 300 K, are used to investigate the scattering mechanisms in GaN/InN/AlN double heterojunctions. Theoretical modeling is based on a variational approach to solving Boltzmann transport equation. It is found that dislocation scattering is the dominant scattering mechanisms at low temperatures because of the large lattice mismatch with the substrate and hence the high density of dislocations in these material systems. Nevertheless, InN epilayers are characterized by a high background carrier density, probably associated with unwanted impurities. Therefore, we also included in our calculations the ionized impurity scattering. However, the effect of ionized impurity scattering as well as the acoustic phonon scattering, remote- background-ionized impurity scattering, and interface roughness scattering on electron mobility are much smaller than that of dislocation scattering. The dislocation densities, in samples with InN thicknesses of 0.4, 0.6 and 0.8 {mu}m, are then determined from the best fit to the experimental data for the low-temperature transport mobility (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. The Little Inn at the Crossroads: A Spiritual Approach to the Design of a Leadership Course.

    Science.gov (United States)

    Bento, Regina F.

    2000-01-01

    A course on spiritual dimensions of leadership was designed using the metaphor of an inn at a crossroads. The inn included a virtual library of Web-based texts and studio space for creativity and self-expression. Seven workshops explored the following themes: language of leadership and change, personal leadership qualities, vision and mission,…

  8. Anisotropic cubic curvature couplings

    CERN Document Server

    Bailey, Quentin G

    2016-01-01

    To complement recent work on tests of spacetime symmetry in gravity, cubic curvature couplings are studied using an effective field theory description of spacetime-symmetry breaking. The associated mass dimension 8 coefficients for Lorentz violation studied do not result in any linearized gravity modifications and instead are revealed in the first nonlinear terms in an expansion of spacetime around a flat background. We consider effects on gravitational radiation through the energy loss of a binary system and we study two-body orbital perturbations using the post-Newtonian metric. Some effects depend on the internal structure of the source and test bodies, thereby breaking the Weak Equivalence Principle for self-gravitating bodies. These coefficients can be measured in solar-system tests, while binary-pulsar systems and short-range gravity tests are particularly sensitive.

  9. Momentum relaxation of electrons in InN

    Energy Technology Data Exchange (ETDEWEB)

    Zanato, D.; Balkan, N.; Boland-Thoms, A. [University of Essex, Department of Electronic Systems Engineering, Colchester (United Kingdom); Tiras, E. [Hacettepe University, Faculty of Engineering, Department of Physics, Beytepe, Ankara (Turkey); Wah, J.Y. [CSSI, Faculty of Engineering, Multimedia University, Cyberjaya 63100 (Malaysia); Hill, G. [University of Sheffield, Department of Electronic and Electrical Engineering, Sheffield (United Kingdom)

    2005-05-01

    We report on our experimental and theoretical studies concerning the temperature dependence of electron mobility in an InN epilayer grown on sapphire substrate using molecular beam epitaxy (MBE). The Hall mobility is found to slightly decrease with increasing temperatures, ranging from 490 cm{sup 2}V{sup -1}s{sup -1} at 77 K to 445 cm{sup 2}V{sup -1}s{sup -1} at 300 K while the carrier concentration is independent on temperature. We consider the effect of optical phonon scattering, ionised impurity scattering and dislocation scattering to model the observed temperature dependence of the mobility. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Molecular beam epitaxy of InN dots on nitrided sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Romanyuk, Yaroslav E.; Dengel, Radu-Gabriel; Stebounova, LarissaV.; Leone, Stephen R.

    2007-04-20

    A series of self-assembled InN dots are grown by radio frequency (RF) plasma-assisted molecular beam epitaxy (MBE) directly on nitrided sapphire. Initial nitridation of the sapphire substrates at 900 C results in the formation of a rough AlN surface layer, which acts as a very thin buffer layer and facilitates the nucleation of the InN dots according to the Stranski-Krastanow growth mode, with a wetting layer of {approx}0.9 nm. Atomic force microscopy (AFM) reveals that well-confined InN nanoislands with the greatest height/width at half-height ratio of 0.64 can be grown at 460 C. Lower substrate temperatures result in a reduced aspect ratio due to a lower diffusion rate of the In adatoms, whereas the thermal decomposition of InN truncates the growth at T>500 C. The densities of separated dots vary between 1.0 x 10{sup 10} cm{sup -2} and 2.5 x 10{sup 10} cm{sup -2} depending on the growth time. Optical response of the InN dots under laser excitation is studied with apertureless near-field scanning optical microscopy and photoluminescence spectroscopy, although no photoluminescence is observed from these samples. In view of the desirable implementation of InN nanostructures into photonic devices, the results indicate that nitrided sapphire is a suitable substrate for growing self-assembled InN nanodots.

  11. Molecular beam epitaxy of InN dots on nitrided sapphire

    Energy Technology Data Exchange (ETDEWEB)

    Romanyuk, Yaroslav E.; Dengel, Radu-Gabriel; Stebounova, LarissaV.; Leone, Stephen R.

    2007-04-20

    A series of self-assembled InN dots are grown by radio frequency (RF) plasma-assisted molecular beam epitaxy (MBE) directly on nitrided sapphire. Initial nitridation of the sapphire substrates at 900 C results in the formation of a rough AlN surface layer, which acts as a very thin buffer layer and facilitates the nucleation of the InN dots according to the Stranski-Krastanow growth mode, with a wetting layer of {approx}0.9 nm. Atomic force microscopy (AFM) reveals that well-confined InN nanoislands with the greatest height/width at half-height ratio of 0.64 can be grown at 460 C. Lower substrate temperatures result in a reduced aspect ratio due to a lower diffusion rate of the In adatoms, whereas the thermal decomposition of InN truncates the growth at T>500 C. The densities of separated dots vary between 1.0 x 10{sup 10} cm{sup -2} and 2.5 x 10{sup 10} cm{sup -2} depending on the growth time. Optical response of the InN dots under laser excitation is studied with apertureless near-field scanning optical microscopy and photoluminescence spectroscopy, although no photoluminescence is observed from these samples. In view of the desirable implementation of InN nanostructures into photonic devices, the results indicate that nitrided sapphire is a suitable substrate for growing self-assembled InN nanodots.

  12. Selective-Area Growth of Transferable InN Nanocolumns by Using Anodic Aluminum Oxide Nanotemplates

    Science.gov (United States)

    Wang, Xiao; Zhang, Guozhen; Xu, Yang; Wu, Hao; Liu, Chang

    2017-02-01

    InN nanocolumn arrays were grown on c-plane sapphire with and without anodic aluminum oxide (AAO) nanotemplates. The crystalline quality of InN nanocolumns was significantly improved by selective-area growth (SAG) using AAO templates, as verified by X-ray diffraction measurements. Then, InN nanocolumns were transferred onto p-type silicon substrates after etching off the AAO templates. Current-voltage characteristic of the transferred n-InN/p-Si heterojunctions shows on/off ratio as high as 4.65 × 103 at 2 V. This work offers a potential way to grow transferable devices with improving performances.

  13. Stability and electronic structure of InN nanotubes from first-principles study

    Institute of Scientific and Technical Information of China (English)

    Chen Li-Juan

    2006-01-01

    The stability and electronic structure of hypothetical InN nanotubes were studied by first-principles density functional theory.It was found that the strain energies of InN nanotubes are smaller than those of carbon nanotubes of the same radius.Single-wall zigzag InN nanotubes were found to be semiconductors with a direct band gap while the armchair counterparts have an indirect band gap.The band gaps of nanotubes decrease with increasing diameter,similar to the case of carbon nanotubes.

  14. Intrinsic electronic properties of high-quality wurtzite InN

    Science.gov (United States)

    Eisele, H.; Schuppang, J.; Schnedler, M.; Duchamp, M.; Nenstiel, C.; Portz, V.; Kure, T.; Bügler, M.; Lenz, A.; Dähne, M.; Hoffmann, A.; Gwo, S.; Choi, S.; Speck, J. S.; Dunin-Borkowski, R. E.; Ebert, Ph.

    2016-12-01

    Recent reports suggested that InN is a highly unusual III-V semiconductor, whose behavior fundamentally differs from that of others. We therefore analyzed its intrinsic electronic properties on the highest available quality InN layers, demonstrating the absence of electron accumulation at the (10 1 ¯0 ) cleavage surface and in the bulk. The bulk electron density is governed solely by dopants. Hence, we conclude that InN acts similarly to the other III-V semiconductors and previously reported intriguing effects are related to low crystallinity, surface decomposition, nonstoichiometry, and/or In adlayers.

  15. An investigation of electronic and optical properties of InN nanosheet by first principle study

    Science.gov (United States)

    Farzan, M.; Elahi, S. M.; Salehi, H.; Abolhassani, M. R.

    2017-07-01

    In this work, we investigated electronic and optical properties of InN nanosheet using density function theory (DFT) implemented in Wien2k code. We calculated the dielectric function, absorption coefficient, optical conductivity, refraction index, extinction index, reflectivity, and energy loss function of the InN nanosheet within GGA (PBE) and Engel-Vosko (E.V) approximation in two directions E||x (electric field parallel to nanosheet) and E||z (electric field perpendicular to nanosheet), we also calculated the band gap energy within GGA (PBE) and E.V approximations. Optical conductivity in directions to x and z shows that InN nanosheet has semiconductor properties. At the end, we calculated electronic and optical properties, and elastic constant of InN Bulk (wurtzite).

  16. A Cubic Tree Taper Model

    National Research Council Canada - National Science Library

    Goodwin, Adrian N

    2009-01-01

    A flexible tree taper model based on a cubic polynomial is described. It is algebraically invertible and integrable, and can be constrained by one or two diameters, neither of which need be diameter at breast height (DBH...

  17. The electronic structures of AlN and InN wurtzite nanowires

    Science.gov (United States)

    Xiong, Wen; Li, Dong-Xiao

    2017-07-01

    We derive the relations between the analogous seven Luttinger-Kohn parameters and six Rashba-Sheka-Pikus parameters for wurtzite semiconductors, which can be used to investigate the electronic structures of some wurtzite semiconductors such as AlN and InN materials, including their low-dimensional structures. As an example, the electronic structures of AlN and InN nanowires are calculated by using the derived relations and six-band effective-mass k · p theory. Interestingly, it is found that the ground hole state of AlN nanowires is always a pure S state whether the radius R is small (1 nm) or large (6 nm), and the ground hole state only contains | Z > Bloch orbital component. Therefore, AlN nanowires is the ideal low-dimensional material for the production of purely linearly polarized π light, unlike ZnO nanowires, which emits plane-polarized σ light. However, the ground hole state of InN nanowires can be tuned from a pure S state to a mixed P state when the radius R is larger than 2.6 nm, which will make the polarized properties of the lowest optical transition changes from linearly polarized π light to plane-polarized σ light. Meanwhile, the valence band structures of InN nanowires will present strong band-crossings when the radius R increases to 6 nm, and through the detail analysis of possible transitions of InN nanowires at the Γ point, we find some of the neighbor optical transitions are almost degenerate, because the spin-orbit splitting energy of InN material is only 0.001 eV. Therefore, it is concluded that the electronic structures and optical properties of InN nanowires present great differences with that of AlN nanowires.

  18. PLAN DE MARKETING PARA EL HOTEL CARRIZAL INN

    Directory of Open Access Journals (Sweden)

    Ángel Guillermo Félix Mendoza

    2015-06-01

    Full Text Available El objetivo principal de esta investigación fue la elaboración de un plan de marketing para el Hotel Carrizal Inn ubicado en la ciudad de Calceta, provincia de Manabí, Ecuador. Se estructuraron tres fases metodológicas, el diagnóstico situacional, estudio de mercado y plan turístico. En la primera fase se delimitó el área de estudio; además se efectuó un análisis interno y externo, utilizando matrices de diagnóstico como la evaluación de factores internos y externos, matriz de competidores y matriz de diagnóstico de fortalezas, oportunidades, debilidades y amenazas. En el estudio de mercado se analizaron los componentes de oferta y demanda del hotel, se determinaron algunas fallas en la denominación utilizada, según los criterios para la categorización hotelera manejada por el Ministerio de Turismo. En función del diagnóstico FODA, se generaron estrategias para el posicionamiento y comercialización del hotel. Mediante las encuestas realizadas a los huéspedes se pudo conocer el perfil del visitante que llega al hotel y se elaboró un plan publicitario, en el cual sobresale el logotipo y slogan, tríptico promocional, la promoción en página web y redes sociales. Se establecieron estrategias del mix para minimizar falencias operativas en el hotel. Se concluye que la principal nomenclatura utilizada no concuerda con los parámetros establecidos por el Ministerio de Turismo, por lo que se plantea reestructurar ciertas áreas específicas como la cantidad de habitaciones o cambiar la denominación a hostal.

  19. Investigation on quality of cubic GaN/GaAs (100) by double-crystal X-ray diffraction

    Institute of Scientific and Technical Information of China (English)

    徐大鹏; 王玉田; 杨辉; 郑联喜; 李建斌; 段俐宏; 吴荣汉

    1999-01-01

    Cubic GaN was grown on GaAs (100) by low pressure metal organic chemical vapor deposition (MOCVD). X-ray diffraction, scanning electron microscope (SEM) and photoluminescence (PL) spectra were performed to characterize the quality of the GaN film. The PL spectra of cubic GaN thin films being thicker than 1.5 μm were reported. Triple-crystal diffraction to analyze orientation distributions and strain of the thin films was also demonstrated.

  20. Body-centered-cubic Ni and its magnetic properties.

    Science.gov (United States)

    Tian, C S; Qian, D; Wu, D; He, R H; Wu, Y Z; Tang, W X; Yin, L F; Shi, Y S; Dong, G S; Jin, X F; Jiang, X M; Liu, F Q; Qian, H J; Sun, K; Wang, L M; Rossi, G; Qiu, Z Q; Shi, J

    2005-04-08

    The body-centered-cubic (bcc) phase of Ni, which does not exist in nature, has been achieved as a thin film on GaAs(001) at 170 K via molecular beam epitaxy. The bcc Ni is ferromagnetic with a Curie temperature of 456 K and possesses a magnetic moment of 0.52+/-0.08 micro(B)/atom. The cubic magnetocrystalline anisotropy of bcc Ni is determined to be +4.0x10(5) ergs x cm(-3), as opposed to -5.7x10(4) ergs x cm(-3) for the naturally occurring face-centered-cubic (fcc) Ni. This sharp contrast in the magnetic anisotropy is attributed to the different electronic band structures between bcc Ni and fcc Ni, which are determined using angle-resolved photoemission with synchrotron radiation.

  1. Properties of inductively coupled N2 plasma processed AlInN thin film prepared by post annealing of rf sputtered Al/InN stack

    Science.gov (United States)

    Shanmugan, S.; Mutharasu, D.

    2016-12-01

    InN is a potential material for low cost tandem solar cells and its combination with Si could make the cell conversion efficiency over 30%. Doping into InN is a promising method which alters the properties of InN thin film. In this work, InN thin film was deposited on Si substrate and the doping was achieved by stacking Al elemental layer on InN thin film followed by annealing process. The doped InN (AlInN) thin film was characterized and confirmed the formation of (002) and (103) oriented phases. The prepared AlInN thin film was plasma processed using Inductively coupled plasma (ICP) in presence of N2 gas and the surface and structural properties was modified. The N2 plasma was influenced the preferred orientation of AlInN thin film and their structural parameters such as crystallite size, strain and dislocation density noticeably. Very smooth surface (<4 nm) with small particle size (97 nm) of AlInN thin film was achieved for 15 sccm flow rate during the plasma process. Very low value in leakage current was confirmed for AlInN thin film processed at 15 sccm N2 flow by current-voltage (IV) characteristics.

  2. Epitaxial growth and characterization of InN nanorods and compact layers on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Garcia, M.A.; Grandal, J.; Calleja, E. [ISOM and Departamento de Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria, 28040 Madrid (Spain); Lazic, S.; Calleja, J.M. [Dpt. Fisica de Materiales, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Trampert, A. [Paul-Drude-Institut fuer Festkoerperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2006-06-15

    This work reports on the morphology and optical properties of wurtzite InN layers grown by plasma assisted molecular beam epitaxy (PA-MBE) on Si(111) substrates. The layer morphology can be controlled by the effective indium to nitrogen molecular flux ratio, from N-rich conditions that lead to InN nanorods, to stoichiometric conditions leading to compact InN layers. The nanorods deliver a much higher intensity of the photoluminescence emission than compact layers, with a full width at half maximum down to 34 meV, indicative of a high crystal quality. Raman and X-ray measurements on the InN nanorods and compact layers confirm the practical full relaxation of both types of materials. TEM measurements reveal a perfect epitaxial alignment of Si substrate-AlN buffer and InN epilayer with clean AlN-InN interfaces when growth conditions are optimized. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Universal Reconfiguration of (Hyper-)cubic Robots

    OpenAIRE

    Abel, Zachary; Kominers, Scott D.

    2008-01-01

    We study a simple reconfigurable robot model which has not been previously examined: cubic robots comprised of three-dimensional cubic modules which can slide across each other and rotate about each others' edges. We demonstrate that the cubic robot model is universal, i.e., that an n-module cubic robot can reconfigure itself into any specified n-module configuration. Additionally, we provide an algorithm that efficiently plans and executes cubic robot motion. Our results directly extend to a...

  4. InN Segregation in InGaN Layers Grownby Metalorganic Chemical Vapor Deposition%MOCVD生长的InGaN薄膜中InN分凝的研究

    Institute of Scientific and Technical Information of China (English)

    秦志新; 陈志忠; 童玉珍; 陆曙; 张国义

    2001-01-01

    The amount of InN segregated in InGaN films grown by MOCVD was estimated by Xray diffraction measurement technology. In compositions in the InGaN films are measured as 0.1 ~0.34 by X-ray 2θ scan using Vegard's law. The inclusion of InN in InGaN layers was obtained as 0.068 4 % ~2. 639 6% by measuring the ratio of the integrated intensities of InN (0002) peak to that of InGaN (0002) peak in X-ray rocking curves. The theoretical diffraction intensities from InN and InGaN have been calculated according to the X-ray diffraction theory. The values of InN inclusion for all the samples were less than 3 %, which indicate that degree of phase separation of the samples was low. It was also found that the flow rate of N2 carrier gas and operation pressure strongly affect the InN inclusion in InGaN.%利用X射线衍射(XRD)技术测量了MOCVD生长的InGaN薄膜中的InN分凝量.利用Vegard定理和XRD 2θ扫描测得实验的InGaN薄膜的In组分为0.1~0.34.通过测量XRD摇摆曲线的InN(0002)和InGaN(0002)的积分强度之比测得InN在InGaN中的含量为0.0684%~2.6396%.根据XRD理论,计算出InN和InGaN的理论衍射强度.InN含量在所有样品中均小于3%,这表明样品的相分离度比较低.还发现InN在InGaN薄膜中的含量与氮气载气流量和反应室气压明显相关.

  5. Monte Carlo transport simulation of velocity undershoot in zinc blende and wurtzite InN

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Shulong; Liu, Hongxia; Gao, Bo; Zhuo, Qingqing [School of Microelectronics, Key Laboratory of Wide Band-gap Semiconductor Materials and Device, Xidian University, Xi& #x27; an, 710071 (China)

    2012-09-15

    Velocity undershoot in zinc blende (ZB) and wurtzite (WZ) InN is investigated by ensemble Monte Carlo (EMC) calculation. The results show that velocity undershoot arises from the relatively long energy relaxation time compared with momentum. Monte Carlo transport simulations over wide range of electric fields is presented in the paper. The results show that velocity undershoot impacts the electron transport greatly, compared with velocity overshoot, when the electric field changes quickly with time and space. A comparison study between WZ and ZB InN shows that WZ InN has more advantages in device applications due to its excellent electron transport properties. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Cubication of Conservative Nonlinear Oscillators

    Science.gov (United States)

    Belendez, Augusto; Alvarez, Mariela L.; Fernandez, Elena; Pascual, Immaculada

    2009-01-01

    A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear…

  7. Cryptographic Analysis in Cubic Time

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis; Seidl, H.

    2004-01-01

    The spi-calculus is a variant of the polyadic pi-calculus that admits symmetric cryptography and that admits expressing communication protocols in a precise though still abstract way. This paper shows that context-independent control flow analysis can be calculated in cubic time despite the fact ...

  8. The diagonalization of cubic matrices

    Science.gov (United States)

    Cocolicchio, D.; Viggiano, M.

    2000-08-01

    This paper is devoted to analysing the problem of the diagonalization of cubic matrices. We extend the familiar algebraic approach which is based on the Cardano formulae. We rewrite the complex roots of the associated resolvent secular equation in terms of transcendental functions and we derive the diagonalizing matrix.

  9. 4th INNS Symposia Series on Computational Intelligence in Information Systems

    CERN Document Server

    Au, Thien

    2015-01-01

    This book constitutes the refereed proceedings of the Fourth International Neural Network Symposia series on Computational Intelligence in Information Systems, INNS-CIIS 2014, held in Bandar Seri Begawan, Brunei in November 2014. INNS-CIIS aims to provide a platform for researchers to exchange the latest ideas and present the most current research advances in general areas related to computational intelligence and its applications in various domains. The 34 revised full papers presented in this book have been carefully reviewed and selected from 72 submissions. They cover a wide range of topics and application areas in computational intelligence and informatics.  

  10. Defeitos intrínsecos e impurezas em nanofios de InN

    OpenAIRE

    Silva, Júlio César da

    2014-01-01

    Nitretos semicondutores do grupo III possuem um enorme potencial para aplicações em fotodetetores e eficientes células solares. Com a recente descoberta do gap de energia do InN, de aproximadamente 0.7 eV, este pode vir a ser um semicondutor de nitreto importante para a indústria. Mais do que isso, nanoestruturas utilizando InN podem ser construídas com diferentes gaps de energia quando combinado com outros elementos ou com a criação de defeitos, o que é desejado para diferente...

  11. High field electron and hole transport in wurtzite InN

    Energy Technology Data Exchange (ETDEWEB)

    Reklaitis, Antanas [Semiconductor Physics Institute, Centre for Physical Sciences and Technology, Vilnius (Lithuania)

    2012-08-15

    A Monte Carlo technique has been used to investigate the steady-state, transient, and small-signal transport of electrons and holes in InN in high electric fields. The drift velocities and diffusion coefficients of electrons and holes are calculated using single-particle Monte Carlo method. The transient drift velocities of electrons and holes are evaluated from ensemble Monte Carlo simulations. The electron small-signal mobility is estimated. The threshold frequency of 550 GHz for the negative differential mobility (NDM) in InN is obtained. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. Formation and Temperature Effect of InN Nanodots by PA-MBE via Droplet Epitaxy Technique.

    Science.gov (United States)

    Chen, Hugo Juin-Yu; Yang, Dian-Long; Huang, Tseh-Wet; Yu, Ing-Song

    2016-12-01

    In this report, self-organized indium nitride nanodots have been grown on Si (111) by droplet epitaxy method and their density can reach as high as 2.83 × 10(11) cm(-2) for the growth at low temperature of 250 °C. Based on the in situ reflection high-energy electron diffraction, the surface condition, indium droplets, and the formation of InN nanodots are identified during the epitaxy. The X-ray photoelectron spectroscopy and photoluminescence measurements have shown the formation of InN nanodots as well. The growth mechanism of InN nanodots could be described via the characterizations of indium droplets and InN nanodots using scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The density of the InN nanodots was less than that of the In droplets due to the surface diffusion and desorption of atoms during the nitridation and annealing process. The average size and density of InN nanodots can be controlled by the substrate temperatures during the growth. For the growth at lower temperature, we obtained the higher density and smaller average size of InN nanodots. To minimize the total surface energy, the coarsening and some preferred orientations of InN nanodots were observed for the growth at high temperature.

  13. Morphology and optical properties of InN layers grown by molecular beam epitaxy on silicon substrates

    Energy Technology Data Exchange (ETDEWEB)

    Grandal, J.; Sanchez-Garcia, M.A.; Calle, F.; Calleja, E. [Universidad Politecnica de Madrid, Ciudad Universitaria, 28040 Madrid (Spain)

    2005-05-01

    This work reports on the morphology and photoluminescence (PL) properties of wurtzite InN layers grown by plasma assisted molecular beam epitaxy (PA-MBE) on AlN-buffered Si(111) substrates. The layer morphology can be controlled by the effective indium to nitrogen molecular flux ratio, from N-rich conditions that lead to columnar InN layers, to stoichiometric conditions leading to coalesced InN layers. X-Ray Diffraction (XRD) rocking curves around the InN (002) reflection yield a minimum value of 682 arcsec full width at half maximum (FWHM) for a coalesced InN layer. PL intensity from columnar InN samples is two orders of magnitude stronger than that corresponding to coalesced material, pointing to a much higher crystalline quality of the former. PL spectra in columnar InN layers reveal an emission at 0.75 eV (16 K) that follows the typical band-gap temperature dependence and shows a linear trend with the excitation power, suggesting a band-edge recombination that yields an estimate of the energy gap for InN around 0.72 eV at room temperature. No other emissions are observed at higher energies. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  14. Cubic Gallium Nitride on Micropatterned Si (001) for Longer Wavelength LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Durniak, Mark T. [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Materials Science and Engineering; Chaudhuri, Anabil [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials; Smith, Michael L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Material Sciences; Allerman, Andrew A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Advanced Material Sciences; Lee, S. C. [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials; Brueck, S. R. J. [Univ. of New Mexico, Albuquerque, NM (United States). Center for High Technology Materials; Wetzel, Christian [Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Physics, Applied Physics, and Astronomy and Dept. of Materials Science and Engineering

    2016-03-01

    GaInN/GaN heterostructures of cubic phase have the potential to overcome the limitations of wurtzite structures commonly used for light emitting and laser diodes. Wurtzite GaInN suffers from large internal polarization fields, which force design compromises ( 0001 ) towards ultra-narrow quantum wells and reduce recombination volume and efficiency. Cubic GaInN microstripes grown at Rensselaer Polytechnic Institute by metal organic vapor phase epitaxy on micropatterned Si , with {111} v-grooves oriented along Si ( 001 ) , offer a system free of internal polarization fields, wider quantum wells, and smaller <00$\\bar1$> bandgap energy. We prepared 6 and 9 nm Ga x In 1-x N/GaN single quantum well structures with peak wavelength ranges from 520 to 570 nm with photons predominately polarized perpendicular to the grooves. We estimate a cubic InN composition range of 0 < x < 0.5 and an upper limit of the internal quantum efficiency of 50%. Stripe geometry and polarization may be suitable for mode confinement and reduced threshold stimulated emission.

  15. Cubication of conservative nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Belendez, Augusto; Alvarez, Mariela L [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, Elena; Pascual, Inmaculada [Departamento de Optica, FarmacologIa y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es

    2009-09-15

    A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear and cubic terms depend on the initial amplitude, A, while in a Taylor expansion of the restoring force these coefficients are independent of A. The replacement of the original nonlinear equation by an approximate Duffing equation allows us to obtain an approximate frequency-amplitude relation as a function of the complete elliptic integral of the first kind. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of this scheme.

  16. Study of High Quality Indium Nitride Films Grown on Si(100 Substrate by RF-MOMBE with GZO and AlN Buffer Layers

    Directory of Open Access Journals (Sweden)

    Wei-Chun Chen

    2012-01-01

    Full Text Available Wurtzite structure InN films were prepared on Si(100 substrates using radio-frequency metal-organic molecular beam epitaxy (RF-MOMBE system. Ga-doped ZnO (GZO and Amorphous AlN (a-AlN film were used as buffer layers for InN films growth. Structural, surface morphology and optical properties of InN films were investigated by X-ray diffraction (XRD, field emission scanning electron microscopy (FE-SEM, transmission electron microscopy (TEM, and photoluminescence (PL. XRD results indicated that all InN films exhibited preferred growth orientation along the c-axis with different intermediate buffers. TEM images exhibit the InN/GZO growth by two-dimensional mode and thickness about 900 nm. Also, the InN films can be obtained by growth rate about ~1.8 μm/h. Optical properties indicated that the band gap of InN/GZO is about 0.79 eV. These results indicate that the control of buffer layer is essential for engineering the growth of InN on silicon wafer.

  17. Cubic Matrix, Nambu Mechanics and Beyond

    OpenAIRE

    Kawamura, Y

    2002-01-01

    We propose a generalization of cubic matrix mechanics by introducing a canonical triplet and study its relation to Nambu mechanics. The generalized cubic matrix mechanics we consider can be interpreted as a “quantum” generalization of Nambu mechanics.

  18. Cubical sets and the topological topos

    DEFF Research Database (Denmark)

    Spitters, Bas

    2016-01-01

    Coquand's cubical set model for homotopy type theory provides the basis for a computational interpretation of the univalence axiom and some higher inductive types, as implemented in the cubical proof assistant. This paper contributes to the understanding of this model. We make three contributions...... show that it can also be a target for cubical realization by showing that Coquand's cubical sets classify the geometric theory of flat distributive lattices. As a side result, we obtain a simplicial realization of a cubical set. 2. Using the internal `interval' in the topos of cubical sets, we...... construct a Moore path model of identity types. 3. We construct a premodel structure internally in the cubical type theory and hence on the fibrant objects in cubical sets....

  19. Molecular beam epitaxy of cubic III-nitrides on GaAs substrates

    Energy Technology Data Exchange (ETDEWEB)

    As, D.J.; Schikora, D.; Lischka, K. [Dept. of Physics, Univ. of Paderborn, Paderborn (Germany)

    2003-07-01

    Molecular beam epitaxy has successfully been used to grow crystalline layers of group III-nitrides (GaN, AlN and InN) with cubic (zinc-blende) structure on GaAs substrates. In this article, we discuss these efforts that, despite inherent difficulties due to the metastability of the c-III nitrides, led to substantial improvements of the structural, electrical and optical quality of these wide gap semiconductors. We review experimental work concerned with the epitaxy of c-GaN and the control of the growth process in-situ, the important issue of p- and n-type doping of c-GaN and investigations of the structural and optical properties of c-InGaN and c-AlGaN. (orig.)

  20. Numbers for reducible cubic scrolls

    Directory of Open Access Journals (Sweden)

    Israel Vainsencher

    2004-12-01

    Full Text Available We show how to compute the number of reducible cubic scrolls of codimension 2 in (math blackboard symbol Pn incident to the appropriate number of linear spaces.Mostramos como calcular o número de rolos cúbicos redutíveis de codimensão 2 em (math blackboard symbol Pn incidentes a espaços lineares apropriados.

  1. Microstructure of InN epilayers deposited in a close-coupled showerhead reactor

    Science.gov (United States)

    Ganguli, Tapas; Kadir, Abdul; Gokhale, Mahesh; Kumar, Ravi; Shah, A. P.; Arora, B. M.; Bhattacharya, Arnab

    2008-11-01

    The microstructure of epitaxial InN layers has been analyzed by high-resolution X-ray diffraction. Various mosaic block parameters like the tilt and twist between the blocks and an estimate of their lateral coherence lengths have been obtained for a large number of InN epitaxial layers deposited under different V/III ratios, temperatures and reactor pressures. Based on the detailed analysis of the microstrain, we have arrived at a set of optimized deposition parameters for InN in a close-coupled showerhead reactor. We also conclude that excessively high V/III ratio, as mentioned in a few earlier reports, is not a prerequisite for the deposition of high-quality InN layers. In fact, all deposition parameters that lead to an increase in the dissociation of ammonia beyond a critical value lead to increase in the screw dislocation density as indicated by an increase in the tilt value. Interestingly, we find that the density of edge dislocation, indicated by the twist value of the epilayers remains nearly the same irrespective of the deposition parameters.

  2. Self-assembled InN micro-mushrooms by upside-down pendeoepitaxy

    Science.gov (United States)

    Sarwar, A. T. M. Golam; Yang, Fan; Esser, Bryan D.; Kent, Thomas F.; McComb, David W.; Myers, Roberto C.

    2016-06-01

    Self-assembly of hexagonal InN micro-mushrooms on Si (111) substrates by molecular beam epitaxy is reported. Scanning electron microscopy (SEM) reveals hexagonal mushroom caps with smooth top surfaces and a step-like morphology at the bottom surface. A detailed growth study along with SEM measurements reveals that an upside-down pendeoepitaxy mechanism underlies the formation of these structures. Cryogenic temperature photoluminescence measurements on the InN disks show a dominant band-to-acceptor recombination peak at 0.68 eV. Cross-section annular bright field (ABF-) scanning transmission electron microscopy (STEM) reveals that the growth of these structures occurs along the [ 000 1 bar ] crystallographic orientation (N-face). Plan-view high angle annular dark field (HAADF) STEM in the center of the micro-disks reveals a hexagonal lattice indicative of stacking faults. However, at the outskirt of the micro-disk, surprisingly, a honeycomb lattice is observed in plan view STEM indicating a perfect freestanding Wurtzite InN disk that is free of stacking faults. This result opens a pathway for realizing strain-free, freestanding InN substrates.

  3. Cubic colloids : Synthesis, functionalization and applications

    NARCIS (Netherlands)

    Castillo, S.I.R.

    2015-01-01

    This thesis is a study on cubic colloids: micron-sized cubic particles with rounded corners (cubic superballs). Owing to their shape, particle packing for cubes is more efficient than for spheres and results in fascinating phase and packing behavior. For our cubes, the particle volume fraction when

  4. Cubic colloids : Synthesis, functionalization and applications

    NARCIS (Netherlands)

    Castillo, S.I.R.

    2015-01-01

    This thesis is a study on cubic colloids: micron-sized cubic particles with rounded corners (cubic superballs). Owing to their shape, particle packing for cubes is more efficient than for spheres and results in fascinating phase and packing behavior. For our cubes, the particle volume fraction when

  5. Solving Cubic Equations by Polynomial Decomposition

    Science.gov (United States)

    Kulkarni, Raghavendra G.

    2011-01-01

    Several mathematicians struggled to solve cubic equations, and in 1515 Scipione del Ferro reportedly solved the cubic while participating in a local mathematical contest, but did not bother to publish his method. Then it was Cardano (1539) who first published the solution to the general cubic equation in his book "The Great Art, or, The Rules of…

  6. Cubic Icosahedra? A Problem in Assigning Symmetry

    Science.gov (United States)

    Lloyd, D. R.

    2010-01-01

    There is a standard convention that the icosahedral groups are classified separately from the cubic groups, but these two symmetry types have been conflated as "cubic" in some chemistry textbooks. In this note, the connection between cubic and icosahedral symmetries is examined, using a simple pictorial model. It is shown that octahedral and…

  7. Nitridation effects of Si(1 1 1) substrate surface on InN nanorods grown by plasma-assisted molecular beam epitaxy

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Shan [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Tan, Jin, E-mail: jintan_cug@163.com [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China); Engineering Research Center of Nano-Geomaterials of Ministry of Education, China University of Geosciences, Wuhan 430074 (China); Li, Bin; Song, Hao; Wu, Zhengbo; Chen, Xin [Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430074 (China)

    2015-02-05

    Graphical abstract: The morphology evolution of InN nanorods in samples (g)–(i). The alignment of InN nanorods is improved and the deviation angle distribution narrows down with increase in nitriding time. It suggests that extending the nitriding time can enhance the vertical orientation of InN nanorods. - Highlights: • InN nanorods were grown on surface nitrided Si(1 1 1) substrate using PAMBE system. • Nitridation of substrate surface has a strong effect on morphology of InN nanorods. • InN nanorods cannot be formed with 1 min nitridation of Si(1 1 1) substrate. • Increasing nitriding time will increase optimum growth temperature of InN nanorods. • Increasing nitriding time can enhance vertical orientation of InN nanorods. - Abstract: The InN nanorods were grown on Si(1 1 1) substrate by plasma-assisted molecular beam epitaxy (PAMBE) system, with a substrate nitridation process. The effect of nitriding time of Si(1 1 1) substrate on morphology, orientation and growth temperature of InN nanorods was characterized via scanning electron microscopy (SEM) and X-ray diffraction (XRD). The deviation angle of InN nanorods was measured to evaluate the alignment of arrays. The results showed that InN nanorods could not be formed with 1 min nitridation of Si(1 1 1) substrate, but they could be obtained again when the nitriding time was increased to more than 10 min. In order to get aligned InN nanorods, the growth temperature needed to increase with longer nitriding time. The vertical orientation of InN nanorods could be enhanced with increase in nitriding time. The influence of the substrate nitridation on the photoluminescence (PL) spectra of InN nanorods has been investigated.

  8. Cubic metaplectic forms and theta functions

    CERN Document Server

    Proskurin, Nikolai

    1998-01-01

    The book is an introduction to the theory of cubic metaplectic forms on the 3-dimensional hyperbolic space and the author's research on cubic metaplectic forms on special linear and symplectic groups of rank 2. The topics include: Kubota and Bass-Milnor-Serre homomorphisms, cubic metaplectic Eisenstein series, cubic theta functions, Whittaker functions. A special method is developed and applied to find Fourier coefficients of the Eisenstein series and cubic theta functions. The book is intended for readers, with beginning graduate-level background, interested in further research in the theory of metaplectic forms and in possible applications.

  9. Applications of ZnO:Al deposited by RF sputtering to InN low-cost technology

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, S. [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Madrid (Spain); Naranjo, F.B.; Valdueza-Felip, S. [Grupo de Ingenieria Fotonica, Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala Campus Universitario, Madrid (Spain); Abril, O. de [ISOM y Departamento de Fisica Aplicada, Escuela Tecnica Superior de Ingenieros de Telecomunicacion, Universidad Politenica de Madrid (Spain)

    2010-07-15

    InN/ZnO:Al heterostructures deposited at low temperature on different substrates by radio-frequency sputtering were studied. Using ZnO:Al as buffer layer, an improvement in the InN structural properties was achieved. Evaluating ZnO:Al as contact on InN, an Ohmic behaviour for the as-deposited layer on InN was achieved. A specific contact resistance of 2 {omega} cm{sup 2} was measured without any post-deposition treatment. These properties could result very promising for optoelectronic device applications. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  10. Weighted cubic and biharmonic splines

    Science.gov (United States)

    Kvasov, Boris; Kim, Tae-Wan

    2017-01-01

    In this paper we discuss the design of algorithms for interpolating discrete data by using weighted cubic and biharmonic splines in such a way that the monotonicity and convexity of the data are preserved. We formulate the problem as a differential multipoint boundary value problem and consider its finite-difference approximation. Two algorithms for automatic selection of shape control parameters (weights) are presented. For weighted biharmonic splines the resulting system of linear equations can be efficiently solved by combining Gaussian elimination with successive over-relaxation method or finite-difference schemes in fractional steps. We consider basic computational aspects and illustrate main features of this original approach.

  11. Transparent polycrystalline cubic silicon nitride

    Science.gov (United States)

    Nishiyama, Norimasa; Ishikawa, Ryo; Ohfuji, Hiroaki; Marquardt, Hauke; Kurnosov, Alexander; Taniguchi, Takashi; Kim, Byung-Nam; Yoshida, Hidehiro; Masuno, Atsunobu; Bednarcik, Jozef; Kulik, Eleonora; Ikuhara, Yuichi; Wakai, Fumihiro; Irifune, Tetsuo

    2017-01-01

    Glasses and single crystals have traditionally been used as optical windows. Recently, there has been a high demand for harder and tougher optical windows that are able to endure severe conditions. Transparent polycrystalline ceramics can fulfill this demand because of their superior mechanical properties. It is known that polycrystalline ceramics with a spinel structure in compositions of MgAl2O4 and aluminum oxynitride (γ-AlON) show high optical transparency. Here we report the synthesis of the hardest transparent spinel ceramic, i.e. polycrystalline cubic silicon nitride (c-Si3N4). This material shows an intrinsic optical transparency over a wide range of wavelengths below its band-gap energy (258 nm) and is categorized as one of the third hardest materials next to diamond and cubic boron nitride (cBN). Since the high temperature metastability of c-Si3N4 in air is superior to those of diamond and cBN, the transparent c-Si3N4 ceramic can potentially be used as a window under extremely severe conditions. PMID:28303948

  12. Thermodynamic Modeling and Phase Diagrams of Hexagonal and Cubic GaN Single-Crystal Film Growth by ECR-PEMOCVD Method%采用ECR-PEMOCVD方法进行立方和六方GaN单晶薄膜生长的准热力学模型和相图

    Institute of Scientific and Technical Information of China (English)

    王三胜; 顾彪

    2004-01-01

    基于热力学平衡理论,对在电子回旋共振等离子体增强金属有机化学气相沉积系统中的GaN薄膜生长给出了一个化学平衡模型.计算表明,GaN生长的驱动力Δp是以下生长条件的函数:Ⅲ族输入分压,输入Ⅴ/Ⅲ比,生长温度.计算了六方和立方GaN的生长相图,计算结果和我们的实验结果显示出一定的一致性.通过分析,解释了高温和高Ⅴ/Ⅲ比生长条件适合六方GaN的原因.上述模型可以延伸到用于GaN单晶薄膜生长的类似系统中.%Based on thermodynamic equilibrium theory,a chemical equilibrium model for GaN growth is given in electron cyclotron resonance plasma enhanced metalorganic chemical vapor deposition (ECR-PEMOCVD) system.Calculation indicates that the growth driving force are functions of growth conditions:group Ⅲ input partial pressure,input Ⅴ/Ⅲ ratio,and growth temperature.Furthermore,the growth phase diagrams of hexagonal and cubic GaN film growth are obtained,which are consistent with our experimental conditions to some extent.Through analysis,it is explained the reason that high temperature and high input Ⅴ/Ⅲ ratio are favorable for hexagonal GaN film growth.This model can be extended to the similar systems used for GaN single-crystal film growth.

  13. Nonlinear dynamics in wurtzite InN diodes under terahertz radiation

    Institute of Scientific and Technical Information of China (English)

    Feng Wei

    2012-01-01

    We carry out a theoretical study of nonlinear dynamics in terahertz-driven n+nn+ wurtzite InN diodes by using time-dependent drift diffusion equations.A cooperative nonlinear oscillatory mode appears due to the negative differential mobility effect,which is the unique feature of wurtzite InN aroused by its strong nonparabolicity of the T1 valley.The appearance of different nonlinear oscillatory modes,including periodic and chaotic states,is attributed to the competition between the self-sustained oscillation and the external driving oscillation.The transitions between the periodic and chaotic states are carefully investigated using chaos-detecting methods,such as the bifurcation diagram,the Fourier spectrum and the first return map.The resulting bifurcation diagram displays an interesting and complex transition picture with the driving amplitude as the control parameter.

  14. ARTICLES: Effect of Pressure on Electronic Structures and Optical Properties of Rocksalt InN

    Science.gov (United States)

    Xu, Ming-yao; Xu, Ming; Duan, Man-yi; Hu, Qing-ping

    2010-06-01

    The electronic structures and optical properties of rocksalt indium nitride (InN) under pressure were studied using the first-principles calculation by considering the exchange and correlation potentials with the generalized gradient approximation. The calculated lattice constant shows good agreement with the experimental value. It is interestingly found that the band gap energy Eg at the Γ or X point remarkably increases with increasing pressure, but Eg at the L point does not increase obviously. The pressure coefficient of Eg is calculated to be 44 meV/GPa at the Γ point. Moreover, the optical properties of rocksalt InN were calculated and discussed based on the calculated band structures and electronic density of states.

  15. An Analysis of Open-Ended Online Reviews about Bed and Breakfast and Inns in Portugal

    Directory of Open Access Journals (Sweden)

    Sara Evans Machado dos Santos

    2014-03-01

    Full Text Available Researches about User-Generated Content (UGC have gained attention in the fields of Tourism and Hospitality in the last years. This study focus on online reviews about alternative accommodations – B&Bs and Inns. The development of this work was realized applying inductive methods and using an exploratory approach. We collected a sample of 450 online reviews and analyzed them segment by segment, making a total of 4621 segments. We used the Appraisal Theory to assess what attitudes online reviewers are expressing about B&Bs and Inns in Lisbon. We verified that positive appreciation is the most frequent attitude while expressions of affect and judgment are more rare. This study contributes to the academy as it brings a new parameter of analysis of UGC using the Appraisal Theory in the field of Hospitality.

  16. Morphology Controlled Fabrication of InN Nanowires on Brass Substrates

    Directory of Open Access Journals (Sweden)

    Huijie Li

    2016-10-01

    Full Text Available Growth of semiconductor nanowires on cheap metal substrates could pave the way to the large-scale manufacture of low-cost nanowire-based devices. In this work, we demonstrated that high density InN nanowires can be directly grown on brass substrates by metal-organic chemical vapor deposition. It was found that Zn from the brass substrates is the key factor in the formation of nanowires by restricting the lateral growth of InN. The nanowire morphology is highly dependent on the growth temperature. While at a lower growth temperature, the nanowires and the In droplets have large diameters. At the elevated growth temperature, the lateral sizes of the nanowires and the In droplets are much smaller. Moreover, the nanowire diameter can be controlled in situ by varying the temperature in the growth process. This method is very instructive to the diameter-controlled growth of nanowires of other materials.

  17. Reconstruction of an inn fire scene using the Fire Dynamics Simulator (FDS) program.

    Science.gov (United States)

    Chi, Jen-Hao

    2013-01-01

    An inn fire occurring in the middle of the night usually causes a great deal more injuries and deaths. This article examines the case study of an inn fire accident that resulted in the most serious casualties in Taiwan's history. Data based on the official fire investigation report and NFPA921 regulations are used, and the fire scenes are reconstructed using the latest Fire Dynamics Simulator (FDS) program from NIST. The personnel evacuation time and time variants for various fire hazard factors of reconstructive analysis clarify the reason for such a high number of casualties. It reveals that the FDS program has come to play an essential role in fire investigation. The close comparison between simulation result and the actual fire scene also provides fire prevention engineers, a possible utilization of FDS to examine the effects of improved schemes for fire safety of buildings.

  18. Sulfur passivation of surface electrons in highly Mg-doped InN

    Energy Technology Data Exchange (ETDEWEB)

    Linhart, W. M.; Veal, T. D. [Stephenson Institute for Renewable Energy and Department of Physics, University of Liverpool, Liverpool L69 4ZF (United Kingdom); Chai, J. [Department of Electrical and Computer Engineering, University of Canterbury, Christchurch 8140 (New Zealand); McConville, C. F. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom); Durbin, S. M. [Department of Electrical and Computer Engineering, University of Canterbury, Christchurch 8140 (New Zealand); Department of Electrical and Computer Engineering, Western Michigan University, Kalamazoo, Michigan 49008 (United States)

    2013-09-14

    Electron accumulation with a sheet density greater than 10{sup 13} cm{sup −2} usually occurs at InN surfaces. Here, the effects of treatment with ammonium sulfide ((NH{sub 4}){sub 2}S{sub x}) on the surface electronic properties of highly Mg-doped InN (>4×10{sup 18} cm{sup −3}) have been investigated with high resolution x-ray photoemission spectroscopy. The valence band photoemission spectra show that the surface Fermi level decreases by approximately 0.08 eV with (NH{sub 4}){sub 2}S{sub x} treatment, resulting in a decrease of the downward band bending and up to a 70% reduction in the surface electron sheet density.

  19. Solar hot water system installed at Days Inn Motel, Dallas, Texas (Valley View)

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-09-01

    The solar hot water system installed in the Days Inns of America, Inc., Days Inn Motel (120 rooms), I-35/2276 Valley View Lane, Dallas, Texas is described. The solar system was designed by ILI Incorporated to provide 65 percent of the total domestic hot water (DHW) demand. The Solar Energy Products, model CU-30WW liquid (water) flat plate collector (1000 square feet) system automatically drains into the 1000 gallon steel storage tank when the solar pump is not running. This system is one of eleven systems planned. Heat is transferred from the DHW tanks through a shell and tube heat exchanger. A circulating pump between the DHW tanks and heat exchanger enables solar heated water to help make up standby losses. All pumps are controlled by differential temperature controllers. The operation of this system was begun March 11, 1980. The solar components were partly funded ($15,000 of 30,000 cost) by a Department of Energy grant.

  20. Henkilöstövuokrausyritys Shake Inn Oy:n markkinoinnin suunnittelu

    OpenAIRE

    Vertiö, Kati; Lehola, Kyllike

    2013-01-01

    Tämän opinnäytetyö toteutettiin toimeksiantona ravintola-alalla toimivalle henkilöstövuokrausyritys Shake Inn Oy:lle. Opinnäytetyön tavoitteena on kehittää toimeksiantajayrityksen markkinointia ja luoda markkinointisuunnitelma, joka antaa valmiudet markkinoinnin suunnitelmalliseen toteuttamiseen. Tarve markkinointisuunnitelman luomiselle on ajankohtainen, koska toimeksiantajan tavoitteena on laajentaa toimintaansa ja tehostaa näkyvyyttä markkinoilla. Yrityksellä ei ole aikaisempaa markkinoint...

  1. Human Pulpal Reaction to the Modified McInnes Bleaching Technique,

    Science.gov (United States)

    1983-05-01

    Modified McInnes Bleaching Technique is specifically recommended for the treatment of teeth exhibiting endemic dental fluorosis because of its superficial...SUMARY The Modified Mclnnes Bleaching Technique has been recommended for removing the stain of endemic dental fluorosis . This study was designed to...stain from teeth. Ariz Dent J 1966; 12:13-15. 3. Bailey RW, Christen AC. Bleaching of vital teeth stained with endemic dental fluorosis . Oral Surg 1968

  2. Tame Kernels of Pure Cubic Fields

    Institute of Scientific and Technical Information of China (English)

    Xiao Yun CHENG

    2012-01-01

    In this paper,we study the p-rank of the tame kernels of pure cubic fields.In particular,we prove that for a fixed positive integer m,there exist infinitely many pure cubic fields whose 3-rank of the tame kernel equal to m.As an application,we determine the 3-rank of their tame kernels for some special pure cubic fields.

  3. Two-dimensional cubic convolution.

    Science.gov (United States)

    Reichenbach, Stephen E; Geng, Frank

    2003-01-01

    The paper develops two-dimensional (2D), nonseparable, piecewise cubic convolution (PCC) for image interpolation. Traditionally, PCC has been implemented based on a one-dimensional (1D) derivation with a separable generalization to two dimensions. However, typical scenes and imaging systems are not separable, so the traditional approach is suboptimal. We develop a closed-form derivation for a two-parameter, 2D PCC kernel with support [-2,2] x [-2,2] that is constrained for continuity, smoothness, symmetry, and flat-field response. Our analyses, using several image models, including Markov random fields, demonstrate that the 2D PCC yields small improvements in interpolation fidelity over the traditional, separable approach. The constraints on the derivation can be relaxed to provide greater flexibility and performance.

  4. The Influence of Temperature on the Formation of Cubic Structured CdO Nanoparticles and Their Thin Films from Bis(2-hydroxy-1-naphthaldehydatocadmium(II Complex via Thermal Decomposition Technique

    Directory of Open Access Journals (Sweden)

    Thokozani Xaba

    2017-01-01

    Full Text Available Recently, researchers have developed a great interest in the synthesis of metal oxide nanoparticles due to their potential applications in various fields of science and industry, especially in catalysis, due to their high activity. Bis(2-hydroxy-1-naphthaldehydatocadmium(II complexes were prepared and used as precursors for the synthesis of cadmium oxide nanoparticles via thermal decomposition method using HDA as a stabilizing agent. The prepared complexes were also used as single source precursors to prepare CdO thin films onto the glass substrates by spin coating and were annealed at 250, 300, and 350°C, respectively. The precursors were characterized by Fourier transform infrared (FTIR spectroscopy, elemental analysis, nuclear magnetic resonance (NMR, and thermogravimetric analysis (TGA. The synthesized CdO nanoparticles and CdO thin films were characterized by ultraviolet-visible (UV-vis spectroscopy, photoluminescence (PL, X-ray diffraction (XRD, transmission electron microscopy (TEM, scanning electron microscopy (SEM, and atomic force microscopy (AFM.

  5. In-situ growth of micro-cubic Prussian blue-TiO2 composite film as a highly sensitive H2O2 sensor by aerosol co-deposition approach.

    Science.gov (United States)

    Chu, Zhenyu; Shi, Lei; Liu, Yu; Jin, Wanqin; Xu, Nanping

    2013-09-15

    Assisted by the aerosol co-deposition approach, Prussian blue (PB)-TiO2 composite film can be in-situ formed in one step. The architecture of this film is constructed by two layers: PB-TiO2 nano-particles as a ground layer and individual PB micro-cubes as a top layer. Together with the strong electrocatalytic ability from regular PB morphology, TiO2 can denote its high catalysis in H2O2 detection attributed by the extinction of band gap since the combination of PB. Under a low operation potential -0.05V, this sensor exhibits an ultrasensitive ability (1726.8μAmM(-1)cm(-2)), stability and low detection limit (1.5μM) in H2O2 analysis. The application of this composite material is hopeful to extend in complex physiological analysis, and the preparation approach is promising to extend in more composite materials in-situ synthesis. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Catalyst free self-assembled growth of InN nanorings on stepped Si (5 5 3) surface

    Energy Technology Data Exchange (ETDEWEB)

    Chauhan, Amit Kumar Singh; Kumar, Mukesh; Gupta, Govind, E-mail: govind@nplindia.org

    2015-08-01

    Highlights: • Novel technique to synthesis self-assembled InN nanorings by low energy N. • Anisotropic strain relaxation driven self-assembly lead to formation of nanorings. • Strong downward band bending in VB-spectra signify large electron accumulation. - Abstract: A novel technique for synthesis of high crystalline quality self-assembled InN nanorings, by nitriding the bulk deposited In/Si (5 5 3)-1 × 4 system using low energy N{sub 2}{sup +} ions at 520 °C, has been demonstrated. Scanning electron microscopy images reveal the formation of ring shaped InN structures with average size ∼500 nm. Anisotropic strain relaxation via self assembly could be the driving force for the formation of these InN rings on reconstructed Si (5 5 3) surface. High resolution X-ray diffraction analysis indicates high crystalline quality of these wurtzite InN nanostructures with c-plane. A strong downward band bending was observed in X-ray photoelectron spectroscopy valence band spectra which signify the large electron accumulation in the InN nanostructures.

  7. First principles study of effects of vacancies on electronic, magnetic and optical properties of InN nanosheet

    Science.gov (United States)

    Farzan, M.; Elahi, S. M.; Abolhassani, M. R.; Salehi, H.

    2017-05-01

    Based on the first principle study within the generalized gradient approximation (GGA) in the density functional theory (DFT) implemented in Wien2k code, the effects of vacancies on electronic, magnetic and optical properties of InN nanosheet were investigated. We found that the vacancies in InN nanosheet induce spin polarized states in the band gap, and VN-defect, VIn-defect and VIn&N-defect induce local magnetic moments of (-0.01)μB , 3.0μB and 2.0μB , respectively. Also, we calculated the dielectric function, refraction index, extinction index, reflectivity, absorption coefficient, optical conductivity and energy loss function of the perfect InN nanosheet and VN-defect, VIn-defect and VIn&N-defect of InN nanosheet for both polarization directions of light, i.e. E||x (electric field parallel to nanosheet) and E||z (electric field perpendicular to nanosheet). Our results show that InN nanosheet is a semiconductor which is dependent on the type of vacancies and that the optical properties of perfect and defective InN nanosheets are anisotropic for both polarization states.

  8. Ultrafast Carrier Relaxation in InN Nanowires Grown by Reactive Vapor Transport

    Directory of Open Access Journals (Sweden)

    Zervos Matthew

    2008-01-01

    Full Text Available Abstract We have studied femtosecond carrier dynamics in InN nanowires grown by reactive vapor transport. Transient differential absorption measurements have been employed to investigate the relaxation dynamics of photogenerated carriers near and above the optical absorption edge of InN NWs where an interplay of state filling, photoinduced absorption, and band-gap renormalization have been observed. The interface between states filled by free carriers intrinsic to the InN NWs and empty states has been determined to be at 1.35 eV using CW optical transmission measurements. Transient absorption measurements determined the absorption edge at higher energy due to the additional injected photogenerated carriers following femtosecond pulse excitation. The non-degenerate white light pump-probe measurements revealed that relaxation of the photogenerated carriers occurs on a single picosecond timescale which appears to be carrier density dependent. This fast relaxation is attributed to the capture of the photogenerated carriers by defect/surface related states. Furthermore, intensity dependent measurements revealed fast energy transfer from the hot photogenerated carriers to the lattice with the onset of increased temperature occurring at approximately 2 ps after pulse excitation.

  9. Raman scattering by coupled plasmon-LO phonons in InN nanocolumns

    Energy Technology Data Exchange (ETDEWEB)

    Lazic, S.; Gallardo, E.; Calleja, J.M. [Dept. Fisica de Materiales, Universidad Autonoma de Madrid, 28049 Madrid (Spain); Agullo-Rueda, F. [Materials Science Institute of Madrid, CSIC, 288049 Madrid (Spain); Grandal, J.; Sanchez-Garcia, M.A.; Calleja, E. [ISOM and Departamento de Ingenieria Electronica, ETSIT, Universidad Politecnica de Madrid, 28040 Madrid (Spain)

    2008-07-01

    Raman measurements on high quality, relaxed InN nanocolumns grown on Si(001) and Si(111) substrates by plasma-assisted molecular beam epitaxy are reported. A coupled LO phonon-plasmon mode around 430 cm{sup -1}, together with the uncoupled LO phonon appears in the nanocolumnar samples. The coupled mode is attributed to spontaneous accumulation of electrons at the lateral surfaces of the nanocolumns, while the uncoupled phonon originates from their inner part. Infrared reflectance measurements confirm the presence of electrons in the nanocolumns. The electron density in the accumulation layer depends on the growth temperature and is sensitive to exposure of HCl. Our results indicate that accumulation of intrinsic electrons occurs not only at the polar surfaces of InN layers, but also on non-polar lateral surfaces of InN nanocolumns. Its origin is attributed to an In-rich surface reconstruction of the nanocolumns sidewalls. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. Structural, optical and electrical properties of indium nitride polycrystalline films

    Energy Technology Data Exchange (ETDEWEB)

    Silva, M.V.S. da, E-mail: marcus.sansil@gmail.com [Instituto de Fisica, UFBA, Campus Ondina, 40210-340, Salvador (Brazil); David, D.G.F.; Pepe, I.; Ferreira da Silva, A.; Almeida, J.S. de [Instituto de Fisica, UFBA, Campus Ondina, 40210-340, Salvador (Brazil); Gazoto, A.L. [Instituto de Fisica Gleb Wataghin (IFGW), UNICAMP, 13083-859, Campinas, SP (Brazil); Santos, A.O. dos [Instituto de Fisica Gleb Wataghin (IFGW), UNICAMP, 13083-859, Campinas, SP (Brazil); CCSST, Universidade Federal do Maranhao, 65900-410 Imperatriz, MA (Brazil); Cardoso, L.P.; Meneses, E.A. [Instituto de Fisica Gleb Wataghin (IFGW), UNICAMP, 13083-859, Campinas, SP (Brazil); Graybill, D.L. [75 Logan Street Brooklyn, NY 11208 (United States); Mertes, K.M. [Los Alamos National Laboratory, Los Alamos, NM 8754 (United States)

    2012-05-31

    The structural, optical and electrical properties of InN polycrystalline films on glass substrate are investigated by means of X-ray photoelectron spectroscopy, Raman scattering measurements, X-ray diffraction analysis, optical spectroscopy, and electrical measurements as a function of the inverse of temperature. The absorption edge for the films is most likely due to an impurity band formed by the presence of defects in the material. Such an impurity band, located at 1.6 eV extends itself to about 1.8 eV above the Fermi level, and it is attributed to nitrogen vacancies present in the material. The Raman scattering data also reveal the incorporation of oxygen in the InN films, leading to the formation of the In{sub 2}O{sub 3} amorphous phase during the process of sputtering. Additionally, the X-ray photoelectron spectroscopy of the valence band, which is highly desirable to the determination of the Fermi level, confirms the optical gap energy. Furthermore, the X-ray diffraction patterns of the thinner films present broader peaks, indicating high values for the strain between the film lattice and the glass substrate. Finally, first principles calculations are used to investigate the optical properties of InN and also to support the experimental findings. - Highlights: Black-Right-Pointing-Pointer InN thin films with different thicknesses and good quality were synthesized. Black-Right-Pointing-Pointer Semiconductor behavior and some contamination by In{sub 2}O{sub 3} were found. Black-Right-Pointing-Pointer The band gap was close to 1.8 eV compared to 0.7 eV found in pure InN. Black-Right-Pointing-Pointer The electronic structure for this material was determined.

  11. Research on the Cutting Performance of Cubic Boron Nitride Tools

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    There were only two kinds of superhard tool material at the past, i.e. diamond and cubic boron nitride (CBN). Manmade diamond and CBN are manufactured by the middle of 20th century. Various manufacturing methods and manmade superhard materials were developed later. They were widely used in different industry and science areas. Recently, a new kind of superhard tool material, C 3N 4 coating film, had been developed. American physical scientists, A. M. Liu and M. L. Cohen, designed a new kind of inorganic c...

  12. Cubical local partial orders on cubically subdivided spaces - Existence and construction

    DEFF Research Database (Denmark)

    Fajstrup, Lisbeth

    2006-01-01

    The geometric models of higher dimensional automata (HDA) and Dijkstra's PV-model are cubically subdivided topological spaces with a local partial order. If a cubicalization of a topological space is free of immersed cubic Möbius bands, then there are consistent choices of direction in all cubes...

  13. Cubical local partial orders on cubically subdivided spaces - existence and construction

    DEFF Research Database (Denmark)

    Fajstrup, Lisbeth

    The geometric models of Higher Dimensional Automata and Dijkstra's PV-model are cubically subdivided topological spaces with a local partial order. If a cubicalization of a topological space is free of immersed cubic Möbius bands, then there are consistent choices of direction in all cubes...

  14. CLASSIFICATION OF CUBIC PARAMETERIZED HOMOGENEOUS VECTOR FIELDS

    Institute of Scientific and Technical Information of China (English)

    Karnal H.Yasir; TANG Yun

    2002-01-01

    In this paper the cubic homogeneous parameterized vector fields are studied.The classification of the phase portrait near the critical point is presented. This classification is an extension of the result given by Takens to the cubic homogeneous parameterized vector fields with six parameters.

  15. CLASSIFICATION OF CUBIC PARAMETERIZED HOMOGENEOUS VECTOR FIELDS

    Institute of Scientific and Technical Information of China (English)

    KamalH.Yasir; TNAGYun

    2002-01-01

    In this paper the cubic homogeneous parameterized vector fields are studied.The classification of the phase portrait near the critical point is presented.This classification is an extension of the result given by takens to the cubic homogeneous parameterized vector fields with six parameters.

  16. Comparison study of N- and In-polar {l_brace}0001{r_brace} InN layers grown by MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Dinh, Duc V.; Pristovsek, M.; Solopow, S.; Skuridina, D.; Kneissl, M. [Institute of Solid State Physics, Technische Universitaet Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)

    2012-03-15

    We compare InN layers grown directly on c -plane (0001) sapphire and on (0001) GaN templates using metal-organic vapor phase epitaxy. InN grown on nitridated c -plane sapphire showed N-polarity, while InN grown on c -plane GaN templates showed In-polarity. N-polar and In-polar InN layers showed different surface morphology and crystallinity. N-polar InN was smoothest when grown at higher growth temperatures, while In-polar InN was smoothest at intermediate growth temperatures. Growth mode of the N-polar InN on sapphire is Frank-Van der Merwe, while growth mode of the In-polar InN on GaN templates is Volmer-Weber. Electrical properties were similar for both layers. Lowtemperature photoluminescence of In-polar InN layers is shifted to higher energies most likely due to biaxial compressive stresses. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  17. Ultrahard nanotwinned cubic boron nitride.

    Science.gov (United States)

    Tian, Yongjun; Xu, Bo; Yu, Dongli; Ma, Yanming; Wang, Yanbin; Jiang, Yingbing; Hu, Wentao; Tang, Chengchun; Gao, Yufei; Luo, Kun; Zhao, Zhisheng; Wang, Li-Min; Wen, Bin; He, Julong; Liu, Zhongyuan

    2013-01-17

    Cubic boron nitride (cBN) is a well known superhard material that has a wide range of industrial applications. Nanostructuring of cBN is an effective way to improve its hardness by virtue of the Hall-Petch effect--the tendency for hardness to increase with decreasing grain size. Polycrystalline cBN materials are often synthesized by using the martensitic transformation of a graphite-like BN precursor, in which high pressures and temperatures lead to puckering of the BN layers. Such approaches have led to synthetic polycrystalline cBN having grain sizes as small as ∼14 nm (refs 1, 2, 4, 5). Here we report the formation of cBN with a nanostructure dominated by fine twin domains of average thickness ∼3.8 nm. This nanotwinned cBN was synthesized from specially prepared BN precursor nanoparticles possessing onion-like nested structures with intrinsically puckered BN layers and numerous stacking faults. The resulting nanotwinned cBN bulk samples are optically transparent with a striking combination of physical properties: an extremely high Vickers hardness (exceeding 100 GPa, the optimal hardness of synthetic diamond), a high oxidization temperature (∼1,294 °C) and a large fracture toughness (>12 MPa m(1/2), well beyond the toughness of commercial cemented tungsten carbide, ∼10 MPa m(1/2)). We show that hardening of cBN is continuous with decreasing twin thickness down to the smallest sizes investigated, contrasting with the expected reverse Hall-Petch effect below a critical grain size or the twin thickness of ∼10-15 nm found in metals and alloys.

  18. HOUSE DUST MITE CONTAMINATION IN HOTELS AND INNS IN BANDAR ABBAS, SOUTH OF IRAN

    Directory of Open Access Journals (Sweden)

    M. Soleimani, J. Rafinejad

    2008-07-01

    Full Text Available House dust mites have been shown to be strongly associated with allergic respiratory diseases such as, bronchial asthma, rhinitis and atopic dermatitis in the world. The climatic conditions of Bandar-Abbas, which is located in a coastal area and has a humid subtropical climate, provide a suitable place to proliferate mites. The aim of this study was to determine the contamination rate and analyze the house dust mite fauna in hotels and inns in Bandar-Abbas that had not been investigated previously. In this study 6 hotels and 6 inns were selected randomly in six areas of Bandar-Abbas. Two dust samples were collected from each place with a vacuum cleaner. One square meter of carpets and mattresses were vacuumed for a period of 1 min. Then the samples were cleared in lactic acid and then mites were mounted in Hoyer's medium for study and identification. A total of 2644 mites were collected and identified. The major mite family was Pyroglyphidae (98%. Dermatophagoides pteronyssinus was the most frequent and most numerous species recorded, occurring in 91% of samples examined and forming 88% of the Pyroglyphidae and 86% of the total mite populations. The family Cheyletidae was less commonly found with Cheyletus malaccensis (2%. Most of the mites were isolated from the carpets (57.5%, and a smaller number from mattresses (42.5%. Mites were present in 96% of the dust samples. Results revealed that all inns and 83% of hotels were contaminated by more than one species of mite and 34% of them had a population of more than 100 mites /g dust. This rate of contamination can be a major risk factor in asthma and other respiratory allergic diseases

  19. Cubic Curves, Finite Geometry and Cryptography

    CERN Document Server

    Bruen, A A; Wehlau, D L

    2011-01-01

    Some geometry on non-singular cubic curves, mainly over finite fields, is surveyed. Such a curve has 9,3,1 or 0 points of inflexion, and cubic curves are classified accordingly. The group structure and the possible numbers of rational points are also surveyed. A possible strengthening of the security of elliptic curve cryptography is proposed using a `shared secret' related to the group law. Cubic curves are also used in a new way to construct sets of points having various combinatorial and geometric properties that are of particular interest in finite Desarguesian planes.

  20. Generalized Vaidya spacetime for cubic gravity

    CERN Document Server

    Ruan, Shan-Ming

    2015-01-01

    We present a kind of generalized Vaidya solutions of a new cubic gravity in five dimensions whose field equations in spherically spacetime are always second order like the Lovelock gravity. We also study the thermodynamics of its apparent horizon and get its entropy expression and generalized Misner-Sharp energy. Finally we present the first law and second law hold in this gravity. Although all the results are analogue to those in Lovelock gravity, we in fact introduce the contribution of new cubic term in five dimensions where cubic Lovelock term is just zero.

  1. Cubical sets as a classifying topos

    DEFF Research Database (Denmark)

    Spitters, Bas

    Coquand’s cubical set model for homotopy type theory provides the basis for a computational interpretation of the univalence axiom and some higher inductive types, as implemented in the cubical proof assistant. We show that the underlying cube category is the opposite of the Lawvere theory of De...... Morgan algebras. The topos of cubical sets itself classifies the theory of ‘free De Morgan algebras’. This provides us with a topos with an internal ‘interval’. Using this interval we construct a model of type theory following van den Berg and Garner. We are currently investigating the precise relation...

  2. Key parameters governing the densification of cubic-Li7La3Zr2O12 Li+ conductors

    Science.gov (United States)

    Yi, Eongyu; Wang, Weimin; Kieffer, John; Laine, Richard M.

    2017-06-01

    Cubic-Li7La3Zr2O12 (LLZO) is regarded as one of the most promising solid electrolytes for the construction of inherently safe, next generation all-solid-state Li batteries. Unfortunately, sintering these materials to full density with controlled grain sizes, mechanical and electrochemical properties relies on energy and equipment intensive processes. In this work, we elucidate key parameters dictating LLZO densification by tracing the compositional and structural changes during processing calcined and ball-milled Al3+ doped LLZO powders. We find that the powders undergo ion (Li+/H+) exchange during room temperature processing, such that on heating, the protonated LLZO lattice collapses and crystallizes to its constituent oxides, leading to reaction driven densification at sizes and protonation cannot be decoupled, and actually aid densification. We conclude that using fully decomposed nanoparticle mixtures, as obtained by liquid-feed flame spray pyrolysis, provides an ideal approach to use high surface and reaction energy to drive densification, resulting in pressureless sintering of Ga3+ doped LLZO thin films (25 μm) at 1130 °C/0.3 h to ideal microstructures (95 ± 1% density, 1.2 ± 0.2 μm average grain size) normally accessible only by pressure-assisted sintering. Such films offer both high ionic conductivity (1.3 ± 0.1 mS cm-1) and record low ionic area specific resistance (2 Ω cm2).

  3. Investigation of InN layers grown by molecular beam epitaxy on GaN templates

    Energy Technology Data Exchange (ETDEWEB)

    Vilalta-Clemente, A.; Mutta, G.R.; Chauvat, M.P.; Morales, M.; Doualan, J.L.; Ruterana, P. [CIMAP UMR 6252 CNRS-ENSICAEN-CEA-UCBN, Caen (France); Grandal, J.; Sanchez-Garcia, M.A.; Calle, F. [ISOM y Department de Ingenieria Electronica, E.T.S.I. Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria (Spain); Valcheva, E.; Kirilov, K. [Faculty of Physics, Sofia University (Bulgaria)

    2010-05-15

    An investigation of InN layers grown on GaN templates by molecular beam epitaxy (MBE) has been carried out by X-ray diffraction (XRD), Raman spectroscopy (RS) and photoluminescence (PL). A good correlation is noticed between their crystalline quality and optical properties. The best samples exhibit a PL emission between 0.6 and 0.7 eV. The surface structure was quite different from one sample to the other, pointing out to a critical role of the growth conditions, which probably need to be tightly optimized for a good reproducibility. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  4. Thermodynamic stability of In{sub 1-x-y}Ga{sub x} Al{sub y}N on GaN and InN

    Energy Technology Data Exchange (ETDEWEB)

    Kangawa, Yoshihiro; Kakimoto, Koichi [Research Institute for Applied Mechanics, Kyushu University, 6-1 Kasuga, Fukuoka 816-8580 (Japan); Ito, Tomonori [Department of Physics Engineering, Mie University, 1515 Kamihama, Tsu, Mie 514-8507 (Japan); Koukitu, Akinori [SRI for Future Nano-science and Technology, Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, 2-4-16 Nakamachi, Koganei, Tokyo 184-8588 (Japan)

    2006-06-15

    We studied the thermodynamic stability of InGaAlN alloy based on calculations of enthalpy of mixing using empirical interatomic potentials. We also investigated the influence of lattice constraint from the bottom layer, i.e., (0001)GaN or (0001)InN, on thermodynamic stability of InGaAlN thin films. The results suggest that the maximum point of enthalpy of mixing shifted toward the In-rich side in the case of InGaAlN/GaN and toward the In-poor side in the case of InGaAlN/InN compared with that of bulk In{sub 1-x-y}Ga{sub x}Al{sub y}N at x=0, y=0.5. This implies that lattice constraint from the bottom layer has a significant influence on thermodynamic stability of thin films. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. High reflected cubic cavity as long path absorption cell for infrared gas sensing

    Science.gov (United States)

    Yu, Jia; Gao, Qiang; Zhang, Zhiguo

    2014-10-01

    One direct and efficient method to improve the sensitivity of infrared gas sensors is to increase the optical path length of gas cells according to Beer-Lambert Law. In this paper, cubic shaped cavities with high reflected inner coating as novel long path absorption cells for infrared gas sensing were developed. The effective optical path length (EOPL) for a single cubic cavity and tandem cubic cavities were investigated based on Tunable Diode Laser Absorption Spectroscopy (TDLAS) measuring oxygen P11 line at 763 nm. The law of EOPL of a diffuse cubic cavity in relation with the reflectivity of the coating, the port fraction and side length of the cavity was obtained. Experimental results manifested an increase of EOPL for tandem diffuse cubic cavities as the decrease of port fraction of the connecting aperture f', and the EOPL equaled to the sum of that of two single cubic cavities at f'<0.01. The EOPL spectra at infrared wavelength range for different inner coatings including high diffuse coatings and high reflected metallic thin film coatings were deduced.

  6. A comparative investigation on sub-micrometer InN and GaN Gunn diodes working at terahertz frequency

    Science.gov (United States)

    Yang, Lin'an; Long, Shuang; Guo, Xin; Hao, Yue

    2012-05-01

    We report on a simulation for wurtzite-InN and GaN Gunn diodes with notch-doping and uniform-doping structural transit regions. Results show that 0.3-1.0 μm Gunn diodes with a diode area of 500 μm2 can generate fundamental frequencies of around 0.2-0.8 THz and rf currents of several hundred mA. InN diodes exhibit more stable oscillations, whereas GaN diodes generate higher oscillation frequencies at both dipole-domain mode and accumulation-domain mode due to different negative differential resistance (NDR) characteristics of high-field transport. The sharp NDR region of InN makes it more suitable for short transit region Gunn diode. Higher Irf/Iav and lower bias voltage in InN Gunn diode imply its conversion efficiency significantly higher than GaN diode.

  7. Near-infrared InN quantum dots on high-In composition InGaN

    Science.gov (United States)

    Soto Rodriguez, Paul E. D.; Gómez, Victor J.; Kumar, Praveen; Calleja, Enrique; Nötzel, Richard

    2013-04-01

    We report the growth of InN quantum dots (QDs) on thick InGaN layers with high In composition (>50%) by molecular beam epitaxy. Optimized growth conditions are identified for the InGaN layers at reduced growth temperature and increased active N flux resulting in minimized phase separation and defect generation. The InN QDs grown on top of the optimized InGaN layer exhibit small size, high density, and photoluminescence up to room temperature. The InN/InGaN QDs reveal excellent potential for intermediate band solar cells with the InGaN and InN QD bandgap energies tuned to the best match of absorption to the solar spectrum.

  8. MOVING SCREW DISLOCATION IN CUBIC QUASICRYSTAL

    Institute of Scientific and Technical Information of China (English)

    ZHOU Wang-min; SONG Yu-hai

    2005-01-01

    The elasticity theory of the dislocation of cubic quasicrystals is developed.The governing equations of anti-plane elasticity dynamics problem of the quasicrystals were reduced to a solution of wave equations by introducing displacement functions,and the analytical expressions of displacements, stresses and energies induced by a moving screw dislocation in the cubic quasicrystalline and the velocity limit of the dislocation were obtained. These provide important information for studying the plastic deformation of the new solid material.

  9. 2-rational Cubic Spline Involving Tension Parameters

    Indian Academy of Sciences (India)

    M Shrivastava; J Joseph

    2000-08-01

    In the present paper, 1-piecewise rational cubic spline function involving tension parameters is considered which produces a monotonic interpolant to a given monotonic data set. It is observed that under certain conditions the interpolant preserves the convexity property of the data set. The existence and uniqueness of a 2-rational cubic spline interpolant are established. The error analysis of the spline interpolant is also given.

  10. Semisymmetric Cubic Graphs of Order 162

    Indian Academy of Sciences (India)

    Mehdi Alaeiyan; Hamid A Tavallaee; B N Onagh

    2010-02-01

    An undirected graph without isolated vertices is said to be semisymmetric if its full automorphism group acts transitively on its edge set but not on its vertex set. In this paper, we inquire the existence of connected semisymmetric cubic graphs of order 162. It is shown that for every odd prime , there exists a semisymmetric cubic graph of order 162 and its structure is explicitly specified by giving the corresponding voltage rules generating the covering projections.

  11. Cubical version of combinatorial differential forms

    DEFF Research Database (Denmark)

    Kock, Anders

    2010-01-01

    The theory of combinatorial differential forms is usually presented in simplicial terms. We present here a cubical version; it depends on the possibility of forming affine combinations of mutual neighbour points in a manifold, in the context of synthetic differential geometry.......The theory of combinatorial differential forms is usually presented in simplicial terms. We present here a cubical version; it depends on the possibility of forming affine combinations of mutual neighbour points in a manifold, in the context of synthetic differential geometry....

  12. Planar n{sup +}-in-n silicon pixel sensors for the ATLAS IBL upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Goessling, C.; Klingenberg, R. [Lehrstuhl fuer Experimentelle Physik IV, TU Dortmund, 44221 Dortmund (Germany); Muenstermann, D., E-mail: Daniel.Muenstermann@TU-Dortmund.de [Lehrstuhl fuer Experimentelle Physik IV, TU Dortmund, 44221 Dortmund (Germany); Rummler, A.; Troska, G.; Wittig, T. [Lehrstuhl fuer Experimentelle Physik IV, TU Dortmund, 44221 Dortmund (Germany)

    2011-09-11

    The ATLAS experiment at the LHC is planning to upgrade its pixel detector by the installation of a 4th pixel layer, the insertable b-layer IBL with a mean sensor radius of only 32 mm from the beam axis. Being very close to the beam, the radiation damage of the IBL sensors might be as high as 5x10{sup 15} n{sub eq} cm{sup -2} at their end-of-life. To investigate the radiation hardness and suitability of the current ATLAS pixel sensors for IBL fluences, n{sup +}-in-n silicon pixel sensors from the ATLAS Pixel production have been irradiated by reactor neutrons to the IBL design fluence and been tested with pions at the SPS and with electrons from a {sup 90}Sr source in the laboratory. The collected charge was found to exceed 10 000 electrons per MIP at 1 kV of bias voltage which is in agreement with data collected with strip sensors. With an expected threshold of 3000-4000 electrons, this result suggests that planar n{sup +}-in-n pixel sensors are radiation hard enough to be used as IBL sensor technology.

  13. Roman Inns and Roman Culture%旅馆与古罗马文化

    Institute of Scientific and Technical Information of China (English)

    冯定雄

    2011-01-01

    Inns were the crucial components of Roman society. Roman inns dispersed in all parts of Rome, but most of them were bad conditioned and terrible for life. Inns' social position was very low because they always were censured by Roman government, law and moralists. Though their position was very bad, it was the favorite place for Roman elite. It was the upper-class' haunt that worsened the Roman inns'reputation.%旅馆是罗马社会的重要组成部分。罗马的旅馆遍布罗马全境,大多数的条件都很简陋,旅馆生活也很糟糕。旅馆在罗马社会中的地位极其低下,国家政策、法律规定、社会评价都竭力限制它的发展。尽管罗马旅馆地位的低下,但它却也是自视高贵的罗马上层社会精英们乐此不疲光顾的地方,而正是这些精英们在旅馆中的龌龊表现,更加剧了旅馆的恶劣名声。

  14. From Amateur Astronomer to Observatory Director: The Curious Case of R. T. A. Innes

    Science.gov (United States)

    Orchiston, Wayne

    Robert Innes was one of a select band of amateur astronomers who made the transition to professional ranks towards the end of the nineteenth century. Initially he had a passion for mathematical astronomy, but after settling in Sydney he developed a taste for observational astronomy, specialising in the search for new double stars. He quickly became known for his success in this field and for his publications on solar system perturbations, and with John Tebbutt's patronage managed to secure a clerical position at the Royal Observatory, Cape of Good Hope. Once there he continued to observe in his spare time and to publish, and, with strong support from Sir David Gill, was appointed founding Director of the Transvaal Observatory. By the time he died in 1933, Innes had received an honorary D.Sc. from Leiden University, and had established an international reputation as a positional astronomer. This paper provides an interesting case study of a well-known `amateur-turned-professional', and an example of the ways in which patronage played a key role in nineteenth and early twentieth century Australian and South African astronomy.

  15. InN quantum dots on GaN nanowires grown by MOVPE

    Energy Technology Data Exchange (ETDEWEB)

    Bi, Zhaoxia; Lindgren, David; Johansson, Jonas; Gustafsson, Anders; Borgstroem, Magnus T.; Monemar, Bo; Samuelson, Lars [Solid State Lighting Center, the Nanometer Structure Consortium, Lund University (Sweden); Ek, Martin; Wallenberg, L. Reine [Center for Analysis and Synthesis/nCHREM, Lund University (Sweden); Ohlsson, B. Jonas [QuNano AB, Lund (Sweden)

    2014-04-15

    In this work, growth of InN quantum dots (QDs) on GaN nanowires (NWs) by metal-organic vapour phase epitaxy is demonstrated, illustrating the feasibility to combine 0D and 1D structures for nitride semiconductors. Selective area growth was used to generate arrays of c-oriented GaN NWs using Si{sub 3}N{sub 4} as the mask material. In general, InN QDs tend to form at the NW edges between the m-plane side facets, but the QD growth can also be tuned to the side facets by controlling the growth temperature and the growth rate. TEM characterization reveals that I{sub 1}-type stacking faults are formed in the QDs and originate from the misfit dislocations at the InN/GaN interface. Photoluminescence measurement at 4 K shows that the peak shifts to high energy with reduced dot size. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Solar hot water system installed at Days Inn Motel, Dallas, Texas

    Energy Technology Data Exchange (ETDEWEB)

    1980-09-01

    The solar energy hot water system installed in the Days Inn of America, Inc., Days Inn Motel (100 rooms), I-635/2753 Forrest Lane, Dallas, Texas is described. The solar system was designed by ILI, Inc., to provide 65% of the total Domestic Hot Water (DHW) demand. The liquid flat plate (water) collector is 1000 square feet of solar energy products, Model CU-30W array. Water in the collector system automatically drains into the 1000 gallon steel storage tank located in the mechanical room when the pump is not running. Heat is transferred from the storage tank to DHW tanks through a tube and shell heat exchanger. A circulating pump between the DHW tanks and the heat exchanger enables solar heated water to help make up DHW tank standby losses. All pumps are controlled by differential temperature. Operation of this system was begun March 11, 1980. The solar components were partly funded ($15,000 of $30,000 cost) by the Department of Energy Grant.

  17. Solar hot water system installed at Days Inn Motel, Jacksonville, Florida

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-09-01

    The solar energy hot water system installed in the Days Inns of America, Inc., Days Inn Motel (120 rooms) I-95 and Cagle Road, Jacksonville, Florida, is described. The solar system was designed by ILI, Incorporated to provide 65 percent of the hot water demand. The system is one of eleven systems planned under this grant. Water (in the Solar Energy Products, Model CU-30ww liquid flat plate collector (900 square feet) system) automatically drains into the 1000 gallon lined and vented steel storage tank when the pump is not running. Heat is transferred from storage to Domestic Hot Water (DHW) tanks through a tube and shell heat exchanger. A circulating pump between the DHW tanks and heat exchanger enables solar heated water to help make up DHW standby losses. All pumps are controlled by differential temperature. This system was turned on June 19, 1979. The solar components were partly funded ($15,823 of $31,823 cost) by the Department of Energy.

  18. Structural and elastic properties of InN and InAlN with different surface orientations and doping

    OpenAIRE

    2012-01-01

    Group–III nitrides, InN, GaN, AlN, and their alloys, have revolutionized solid state lighting and continue to attract substantial research interest due to their unique properties and importance for optoelectronics and electronics. Among the group–III nitrides, InN has the lowest effective electron mass and the highest electron mobility, which makes it suitable for high–frequency and high power devices. InxAl1–xN alloys cover the widest wavelength region among any semiconductor systems with ba...

  19. A Dance Class, a Drag King, & the Pedagogical Possibilities of Performative Hip-Hop: An Interview with Carmen Morrison & Alex U. Inn

    Science.gov (United States)

    Schönfeldt-Aultman, Scott M.; Morrison, Carmen

    2015-01-01

    Alex U. Inn is the co-founder and one of the two MCs of the hip-hop drag king group, Momma's Boyz. Momma's Boyz celebrated their tenth anniversary in 2014. Carmen Morrison is the offstage name of Alex U. Inn, though "Carmen" now goes by Alex offstage, as well. Within this interview, the names "Carmen" and "Alex" are…

  20. Preparation of high-pressure phase boron nitride films by physical vapor deposition

    CERN Document Server

    Zhu, P W; Zhao, Y N; Li, D M; Liu, H W; Zou Guang Tian

    2002-01-01

    The high-pressure phases boron nitride films together with cubic, wurtzic, and explosive high-pressure phases, were successfully deposited on the metal alloy substrates by tuned substrate radio frequency magnetron sputtering. The percentage of cubic boron nitride phase in the film was about 50% as calculated by Fourier transform infrared measurements. Infrared peak position of cubic boron nitride at 1006.3 cm sup - sup 1 , which is close to the stressless state, indicates that the film has very low internal stress. Transition electron microscope micrograph shows that pure cubic boron nitride phase exits on the surface of the film. The growth mechanism of the BN films was also discussed.

  1. Initial exploration of growth of InN by electrochemical solution growth.

    Energy Technology Data Exchange (ETDEWEB)

    Waldrip, Karen Elizabeth

    2010-02-01

    This report summarizes a brief and unsuccessful attempt to grow indium nitride via the electrochemical solution growth method and a modification thereof. Described in this report is a brief effort using a $50,000 LDRD award to explore the possibilities of applying the Electrochemical Solution Growth (ESG) technique to the growth of indium nitride (InN). The ability to grow bulk InN would be exciting from a scientific perspective, and a commercial incentive lies in the potential of extending the ESG technique to grow homogeneous, bulk alloys of In{sub x}Ga{sub 1-x}N for light emitting diodes (LEDs) operating in the green region of the spectrum. Indium nitride is the most difficult of the III-nitrides to grow due to its very high equilibrium vapor pressure of nitrogen1. It is several orders of magnitude higher than for gallium nitride or aluminum nitride. InN has a bandgap energy of 0.7eV, and achieving its growth in bulk for large area, high quality substrates would permit the fabrication of LEDs operating in the infrared. By alloying with GaN and AlN, the bulk material used as substrates would enable high efficiency emission wavelengths that could be tailored all the way through the deep ultraviolet. In addition, InN has been shown to have very high electronic mobilities (2700 cm{sup 2}/V s), making it a promising material for transistors and even terahertz emitters. Several attempts at synthesizing InN have been made by several groups. It was shown that metallic indium does not interact with unactivated nitrogen even at very high temperatures. Thus sets up an incompatibility between the precursors in all growth methods: a tradeoff between thermally activating the nitrogen-containing precursor and the low decomposition temperature of solid InN. We have been working to develop a novel growth technique that circumvents the difficulties of other bulk growth techniques by precipitating the column III nitrides from a solvent, such as a molten chloride salt, that

  2. Interpolation by two-dimensional cubic convolution

    Science.gov (United States)

    Shi, Jiazheng; Reichenbach, Stephen E.

    2003-08-01

    This paper presents results of image interpolation with an improved method for two-dimensional cubic convolution. Convolution with a piecewise cubic is one of the most popular methods for image reconstruction, but the traditional approach uses a separable two-dimensional convolution kernel that is based on a one-dimensional derivation. The traditional, separable method is sub-optimal for the usual case of non-separable images. The improved method in this paper implements the most general non-separable, two-dimensional, piecewise-cubic interpolator with constraints for symmetry, continuity, and smoothness. The improved method of two-dimensional cubic convolution has three parameters that can be tuned to yield maximal fidelity for specific scene ensembles characterized by autocorrelation or power-spectrum. This paper illustrates examples for several scene models (a circular disk of parametric size, a square pulse with parametric rotation, and a Markov random field with parametric spatial detail) and actual images -- presenting the optimal parameters and the resulting fidelity for each model. In these examples, improved two-dimensional cubic convolution is superior to several other popular small-kernel interpolation methods.

  3. Cubic Copper Hexacyanoferrates Nanoparticles: Facile Template-Free Deposition and Electrocatalytic Sensing Towards Hydrazine

    Directory of Open Access Journals (Sweden)

    Xingxing Wang

    2011-01-01

    Full Text Available Cubic copper hexacyanoferrate (CuHCF nanoparticles prepared via electrolytic deposition are presented with their morphology and crystalline structure characterized with SEM and XRD. The advantage of this methodology is that it allows the fabrication of uniform cubic nanoparticles with permeable structures onto the desired underlying electrode substrate. It was observed that the CuHCF film acts as a permeable membrane for cations such as K+, Na+, Li+, and NH4+ with a selection order of K+> Li+>NH4+> Na+. Furthermore, the analytical utility of these cubic-like CuHCF morphologies supported on a glassy carbon electrode was evaluated towards the electrochemical oxidation of hydrazine which was found to exhibit a linear response over the range 66 M to 17 mM with a detection limit corresponding to 16.5 M.

  4. Generation of ultra-small InN nanocrystals by pulsed laser ablation of suspension in organic solution

    Energy Technology Data Exchange (ETDEWEB)

    Kursungoez, Canan; Uzcengiz Simsek, Elif; Ortac, Buelend [Bilkent University, Materials Science and Nanotechnology Department, UNAM-National Nanotechnology Research Center, Ankara (Turkey); Bilkent University, Institute of Materials Science and Nanotechnology, Ankara (Turkey); Tuzakli, Refik [Bilkent University, Materials Science and Nanotechnology Department, UNAM-National Nanotechnology Research Center, Ankara (Turkey)

    2017-03-15

    Nanostructures of InN have been extensively investigated since nano-size provides a number of advantages allowing applications in nanoscale electronic and optoelectronic devices. It is quite important to obtain pure InN nanocrystals (InN-NCs) to reveal the characteristic features, which gain interest in the literature. Here, we proposed a new approach for the synthesis of ultra-small hexagonal InN-NCs by using suspension of micron-sized InN powder in ethanol with pulsed laser ablation method. The liquid environment, laser energy and ablation time were optimized and a post-synthesis treatment, centrifugation, was performed to achieve InN-NCs with the smallest size. Besides, the micron-sized InN powder suspension, as a starting material, enabled us to obtain InN-NCs having diameters smaller than 5 nm. We also presented a detailed characterization of InN-NCs and demonstrated that the formation mechanism mainly depends on the fragmentation due to laser irradiation of the suspension. (orig.)

  5. Space charged region in GaN and InN nanocolumns investigated by atomic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cimalla, V.; Ambacher, O. [Institute of Micro- and Nanotechnologies, Technische Universitaet Ilmenau, P.O. Box 100565, 98684 Ilmenau (Germany); Machleidt, T.; Franke, K.H. [Department of Computer Graphics Program, Technische Universitaet Ilmenau, P.O. Box 100565, 98684 Ilmenau (Germany); Ristic, J.; Grandal, J.; Sanchez-Garcia, M.A.; Calleja, E. [ISOM-Dept. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica, 28040 Madrid (Spain); Niebelschuetz, M.

    2008-07-01

    High quality InN and GaN nanocolumns of different length and diameter grown by molecular beam epitaxy (MBE) were electrically characterized directly and non-destructively by Atomic Force Microscopy (AFM) as a function of the column diameter. The 'exact' column diameter was determined from AFM images by Blind Tip Estimation (BTE) and subsequent image reconstruction in order to avoid artefacts due to the finite AFM tip radius. In GaN, the conductivity rises up to a 'critical' diameter due to a depletion region at the surface of the nanocolumns and remains constant above. In contrast, the electron accumulation at the surface causes decreasing conductivity in InN nanocolumns with increasing diameter. Thus, the nanocolumn surface acts as the preferential conduction path. These facts prove that there is electron accumulation in as-grown non-polar InN surfaces, according to calculations of the Fermi level pinning in InN. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Superhard BC(3) in cubic diamond structure.

    Science.gov (United States)

    Zhang, Miao; Liu, Hanyu; Li, Quan; Gao, Bo; Wang, Yanchao; Li, Hongdong; Chen, Changfeng; Ma, Yanming

    2015-01-01

    We solve the crystal structure of recently synthesized cubic BC(3) using an unbiased swarm structure search, which identifies a highly symmetric BC(3) phase in the cubic diamond structure (d-BC(3)) that contains a distinct B-B bonding network along the body diagonals of a large 64-atom unit cell. Simulated x-ray diffraction and Raman peaks of d-BC(3) are in excellent agreement with experimental data. Calculated stress-strain relations of d-BC(3) demonstrate its intrinsic superhard nature and reveal intriguing sequential bond-breaking modes that produce superior ductility and extended elasticity, which are unique among superhard solids. The present results establish the first boron carbide in the cubic diamond structure with remarkable properties, and these new findings also provide insights for exploring other covalent solids with complex bonding configurations.

  7. Cubical Cohomology Ring of 3D Photographs

    CERN Document Server

    Gonzalez-Diaz, Rocio; Medrano, Belen; 10.1002/ima.20271

    2011-01-01

    Cohomology and cohomology ring of three-dimensional (3D) objects are topological invariants that characterize holes and their relations. Cohomology ring has been traditionally computed on simplicial complexes. Nevertheless, cubical complexes deal directly with the voxels in 3D images, no additional triangulation is necessary, facilitating efficient algorithms for the computation of topological invariants in the image context. In this paper, we present formulas to directly compute the cohomology ring of 3D cubical complexes without making use of any additional triangulation. Starting from a cubical complex $Q$ that represents a 3D binary-valued digital picture whose foreground has one connected component, we compute first the cohomological information on the boundary of the object, $\\partial Q$ by an incremental technique; then, using a face reduction algorithm, we compute it on the whole object; finally, applying the mentioned formulas, the cohomology ring is computed from such information.

  8. Temperature dependences of the contact resistivity in ohmic contacts to n{sup +}-InN

    Energy Technology Data Exchange (ETDEWEB)

    Sachenko, A. V.; Belyaev, A. E. [National Academy of Sciences, Lashkaryov Institute of Semiconductor Physics (Ukraine); Boltovets, N. S. [“Orion” Research Institute (Ukraine); Brunkov, P. N.; Jmerik, V. N.; Ivanov, S. V. [Russian Academy of Sciences, Ioffe Physical-Technical Institute (Russian Federation); Kapitanchuk, L. M. [National Academy of Sciences of Ukraine, Paton Electric Welding Institute (Ukraine); Konakova, R. V., E-mail: konakova@isp.kiev.ua; Klad’ko, V. P.; Romanets, P. N.; Saja, P. O.; Safryuk, N. V.; Sheremet, V. N. [National Academy of Sciences, Lashkaryov Institute of Semiconductor Physics (Ukraine)

    2015-04-15

    The temperature dependences of the contact resistivity (ρ{sub c}) of ohmic contacts based on the Au-Ti-Pd-InN system are measured at an InN doping level of 2 × 10{sup 18} cm{sup −3} in the temperature range of 4.2–300 K. At temperatures T > 150 K, linearly increasing dependences ρ{sub c}(T) are obtained. The dependences are explained within the mechanism of thermionic current flow through metal shunts associated with dislocations. Good agreement between theoretical and experimental dependences is achieved assuming that the flowing current is limited by the total resistance of the metal shunts, and the density of conductive dislocations is ∼5 × 10{sup 9} cm{sup −2}. Using the X-ray diffraction method, the density of screw and edge dislocations in the structure under study is measured: their total density exceeds 10{sup 10} cm{sup −2}.

  9. Magnetic-field and temperature dependence of the energy gap in InN nanobelt

    Directory of Open Access Journals (Sweden)

    K. Aravind

    2012-03-01

    Full Text Available We present tunneling measurements on an InN nanobelt which shows signatures of superconductivity. Superconducting transition takes place at temperature of 1.3K and the critical magnetic field is measured to be about 5.5kGs. The energy gap extrapolated to absolute temperature is about 110μeV. As the magnetic field is decreased to cross the critical magnetic field, the device shows a huge zero-bias magnetoresistance ratio of about 400%. This is attributed to the suppression of quasiparticle subgap tunneling in the presence of superconductivity. The measured magnetic-field and temperature dependence of the superconducting gap agree well with the reported dependences for conventional metallic superconductors.

  10. Solar hot water system installed at Quality Inn, Key West, Florida. Final report

    Energy Technology Data Exchange (ETDEWEB)

    1980-04-01

    The solar energy hot water system installed in the Quality Inn, Key West, Florida, which consists of four buildings, is described. Three buildings are low-rise, two-story buildings containing 100 rooms. The fourth is a four-story building with 48 rooms. The solar system was designed to provide approximately 50% of the energy required for the domestic hot water system. The solar system consists of approximately 1400 ft/sup 2/ of flat plate collector, two 500 gal storage tanks, a circulating pump, and a controller. Operation of the system was begun in April 1978, and has continued to date with only three minor interruptions for pump repair. In the first year of operation, it was determined that the use of the solar facility resulted in 40% fuel savings.

  11. Purely cubic action for string field theory

    Science.gov (United States)

    Horowitz, G. T.; Lykken, J.; Rohm, R.; Strominger, A.

    1986-01-01

    It is shown that Witten's (1986) open-bosonic-string field-theory action and a closed-string analog can be written as a purely cubic interaction term. The conventional form of the action arises by expansion around particular solutions of the classical equations of motion. The explicit background dependence of the conventional action via the Becchi-Rouet-Stora-Tyutin operator is eliminated in the cubic formulation. A closed-form expression is found for the full nonlinear gauge-transformation law.

  12. Purely cubic action for string field theory

    Science.gov (United States)

    Horowitz, G. T.; Lykken, J.; Rohm, R.; Strominger, A.

    1986-01-01

    It is shown that Witten's (1986) open-bosonic-string field-theory action and a closed-string analog can be written as a purely cubic interaction term. The conventional form of the action arises by expansion around particular solutions of the classical equations of motion. The explicit background dependence of the conventional action via the Becchi-Rouet-Stora-Tyutin operator is eliminated in the cubic formulation. A closed-form expression is found for the full nonlinear gauge-transformation law.

  13. Influence of hydrogen input partial pressure on the polarity of InN on GaAs (1 1 1)A grown by metalorganic vapor phase epitaxy

    Science.gov (United States)

    Murakami, Hisashi; Eriguchi, Ken-ichi; Torii, Jun-ichi; Cho, Hyun-Chol; Kumagai, Yoshinao; Koukitu, Akinori

    2008-04-01

    Influences of hydrogen input partial pressure in the carrier gas ( F=PHo/(PHo+PNo)) on the crystalline quality and polarities of InN on GaAs (1 1 1)A surfaces were investigated by metalorganic vapor phase epitaxy (MOVPE). It was found that the polarity of the InN was affected by the hydrogen gas in the system regardless of the polarity of GaAs starting substrate. The polarity of InN layer grown with the hydrogen partial pressure of Fo=0.004 was a mixture of In-polarity and N-polarity, while that grown with Fo=0 was In-polarity. Degradation of the crystalline quality of InN grown with Fo=0.004 occurred due to the polarity inversion during the growth. The reason why the polarity of InN was influenced by the hydrogen carrier gas could be explained by the preferential growth of N-polarity InN in the H 2 contained ambient and/or the limiting reaction of InN decomposition.

  14. Development of ZnO:Al-based transparent contacts deposited at low-temperature by RF-sputtering on InN layers

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, S. [Departamento de Energias Renovables, Energia Solar Fotovoltaica, Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas (CIEMAT), Avda. Complutense 22, 28040 Madrid (Spain); Naranjo, F.B.; Valdueza-Felip, S. [Grupo de Ingenieria Fotonica, Departamento de Electronica, Escuela Politecnica Superior, Universidad de Alcala Campus Universitario, 28871 Alcala de Henares, Madrid (Spain); Abril, O. de [ISOM and Departamento de Fisica Aplicada, Escuela Tecnica Superior de Ingenieros de Telecomunicacion, Universidad Politenica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain)

    2012-03-15

    Nitride semiconductors (Al,Ga,In)N attain material properties that make them suitable for photovoltaic and optoelectronics devices to be used in hard environments. These properties include an energy gap continuously tuneable within the energy range of the solar spectrum, a high radiation resistance and thermal stability. The developing of efficient devices requires contacts with low resistivity and high transmittance in visible region. ZnO:Al (AZO) emerges as a feasible candidate for transparent contact to nitride semiconductors, taking advantage of its low resistivity, high transparency in visible wavelengths and a very low lattice mismatch with respect to nitride semiconductors. This work presents a study of the applications of AZO films deposited at low-temperature by RF magnetron sputtering as transparent contact for InN layers. The optimization of AZO conditions deposition lead to the obtaining of contacts which shows an ohmic behaviour for the as-deposited layer, regardless the thickness of the ZnO:Al contact layer. Specific contact resistances of 1.6 {omega}.cm{sup 2} were achieved for the contact with 90 nm thick ZnO:Al layer without any post-deposition treatment (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. Bond percolation in films

    Science.gov (United States)

    Korneta, W.; Pytel, Z.

    1988-04-01

    Bond percolation in films with simple cubic structure is considered. It is assumed that the probability of a bond being present between nearest-neighbor sites depends on the distances to surfaces. Based on the relation between the Potts model and the bond percolation model, and using the mean-field approximation, the phase diagram and profiles of the percolation probability have been obtained.

  16. DEFICIENT CUBIC SPLINES WITH AVERAGE SLOPE MATCHING

    Institute of Scientific and Technical Information of China (English)

    V. B. Das; A. Kumar

    2005-01-01

    We obtain a deficient cubic spline function which matches the functions with certain area matching over a greater mesh intervals, and also provides a greater flexibility in replacing area matching as interpolation. We also study their convergence properties to the interpolating functions.

  17. Counting rational points on cubic curves

    Institute of Scientific and Technical Information of China (English)

    HEATH-BROWN; Roger; TESTA; Damiano

    2010-01-01

    We prove upper bounds for the number of rational points on non-singular cubic curves defined over the rationals.The bounds are uniform in the curve and involve the rank of the corresponding Jacobian.The method used in the proof is a combination of the "determinant method" with an m-descent on the curve.

  18. CONSTRAINED RATIONAL CUBIC SPLINE AND ITS APPLICATION

    Institute of Scientific and Technical Information of China (English)

    Qi Duan; Huan-ling Zhang; Xiang Lai; Nan Xie; Fu-hua (Frank) Cheng

    2001-01-01

    In this paper, a kind of rational cubic interpolation functionwith linear denominator is constructed. The constrained interpolation with constraint on shape of the interpolating curves and on the second-order derivative of the interpolating function is studied by using this interpolation, and as the consequent result, the convex interpolation conditions have been derived.

  19. Anisotropy of a cubic ferromagnet at criticality

    Science.gov (United States)

    Kudlis, A.; Sokolov, A. I.

    2016-10-01

    Critical fluctuations change the effective anisotropy of cubic ferromagnet near the Curie point. If the crystal undergoes phase transition into orthorhombic phase and the initial anisotropy is not too strong, reduced anisotropy of nonlinear susceptibility acquires at Tc the universal value δ4*=2/v* 3 (u*+v*) where u* and v* are coordinates of the cubic fixed point on the flow diagram of renormalization group equations. In the paper, the critical value of the reduced anisotropy is estimated within the pseudo-ɛ expansion approach. The six-loop pseudo-ɛ expansions for u*, v*, and δ4* are derived for the arbitrary spin dimensionality n . For cubic crystals (n =3 ) higher-order coefficients of the pseudo-ɛ expansions obtained turn out to be so small that use of simple Padé approximants yields reliable numerical results. Padé resummation of the pseudo-ɛ series for u*, v*, and δ4* leads to the estimate δ4*=0.079 ±0.006 , indicating that detection of the anisotropic critical behavior of cubic ferromagnets in physical and computer experiments is certainly possible.

  20. Binomial Squares in Pure Cubic Number Fields

    CERN Document Server

    Lemmermeyer, Franz

    2011-01-01

    Let K = Q(\\omega) with \\omega^3 = m be a pure cubic number field. We show that the elements\\alpha \\in K^\\times whose squares have the form a - \\omega form a group isomorphic to the group of rational points on the elliptic curve E_m: y^2= x^3 - m.

  1. The cactus rank of cubic forms

    CERN Document Server

    Bernardi, Alessandra

    2011-01-01

    We prove that the smallest degree of an apolar 0-dimensional scheme to a general cubic form in $n+1$ variables is at most $2n+2$, when $n\\geq 8$, and therefore smaller than the rank of the form. When n=8 we show that the bound is sharp, i.e. the smallest degree of an apolar subscheme is 18.

  2. 193 nm deep-ultraviolet solar-blind cubic boron nitride based photodetectors

    Science.gov (United States)

    Soltani, A.; Barkad, H. A.; Mattalah, M.; Benbakhti, B.; De Jaeger, J.-C.; Chong, Y. M.; Zou, Y. S.; Zhang, W. J.; Lee, S. T.; BenMoussa, A.; Giordanengo, B.; Hochedez, J.-F.

    2008-02-01

    Deep-ultraviolet (DUV) solar-blind photodetectors based on high-quality cubic boron nitride (cBN) films with a metal/semiconductor/metal configuration were fabricated. The design of interdigitated circular electrodes enables high homogeneity of electric field between pads. The DUV photodetectors present a peak responsivity at 180nm with a very sharp cutoff wavelength at 193nm and a visible rejection ratio (180 versus 250nm) of more than four orders of magnitude. The characteristics of the photodetectors present extremely low dark current, high breakdown voltage, and high responsivity, suggesting that cBN films are very promising for DUV sensing.

  3. Ytterbium: Transition at High Pressure from Face-Centered Cubic to Body-Centered Cubic Structure.

    Science.gov (United States)

    Hall, H T; Barnett, J D; Merrill, L

    1963-01-11

    Pressure of 40,000 atmospheres at 25 degrees C induces a phase transformation in ytterbium metal; the face-centered cubic structure changes to body-centered cubic. The radius of the atom changes from 1.82 to 1.75 A. At the same time the atom's volume decreases by 11 percent and the volume, observed macroscopically, decreases 3.2 percent.

  4. Synthesis of indium oxide cubic crystals by modified hydrothermal route for application in room temperature flexible ethanol sensors

    Energy Technology Data Exchange (ETDEWEB)

    Seetha, M., E-mail: seetha.phy@gmail.com [Department of Physics, SRM University, Kattankulathur, Kancheepuram Dt 603 203 (India); Meena, P. [Department of Physics, PSGR Krishnammal College for Women, Coimbatore 641 046 (India); Mangalaraj, D., E-mail: dmraj800@yahoo.com [DRDO-BU Centre for Life Sciences, Bharathiar University Campus, Coimbatore (India); Department of Nanoscience and Technology, Bharathiar University, Coimbatore 641 014 (India); Masuda, Yoshitake [National Institute of Advanced Industrial Science and Technology (AIST), Nagoya 463-8560 (Japan); Senthil, K. [School of Advanced Materials Science and Engineering, Sungkyunkwan University (Suwon Campus), Cheoncheon-dong 300, Jangan-gu, Suwon 440-746 (Korea, Republic of)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer For the first time HMT is used in the preparation of indium oxide. Black-Right-Pointing-Pointer HMT itself acts as base for the precursor and results in cubic indium hydroxide. Black-Right-Pointing-Pointer Modified hydrothermal route used for the preparation of cubic indium oxide crystals. Black-Right-Pointing-Pointer As a new approach a composite film synthesized with prepared indium oxide. Black-Right-Pointing-Pointer Film showed good response to ethanol vapours with quick response and recovery times. - Abstract: Indium oxide cubic crystals were prepared by using hexamethylenetetramine and indium chloride without the addition of any structure directing agents. The chemical route followed in the present work was a modified hydrothermal synthesis. The average crystallite size of the prepared cubes was found to be 40 nm. A blue emission at 418 nm was observed at room temperature when the sample was excited with a 380 nm Xenon lamp. This emission due to oxygen vacancies made the material suitable for gas sensing applications. The synthesized material was made as a composite film with polyvinyl alcohol which was more flexible than the films prepared on glass substrates. This flexible film was used as a sensing element and tested with ethanol vapours at room temperature. The film showed fast response as well as recovery to ethanol vapours with a sensor response of about 1.4 for 100 ppm of the gas.

  5. Dynamic atomic layer epitaxy of InN on/in +c-GaN matrix: Effect of “In+N” coverage and capping timing by GaN layer on effective InN thickness

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, Akihiko, E-mail: yoshi@faculty.chiba-u.jp [Center for SMART Green Innovation Research, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Graduate School of Engineering, Kogakuin University, Hachioji, Tokyo 192-0015 (Japan); Kusakabe, Kazuhide; Hashimoto, Naoki [Center for SMART Green Innovation Research, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan); Hwang, Eun-Sook; Itoi, Takaomi [Graduate School of Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522 (Japan)

    2016-01-11

    The growth front in the self-organizing and self-limiting epitaxy of ∼1 monolayer (ML)-thick InN wells on/in +c-GaN matrix by molecular beam epitaxy (MBE) has been studied in detail, with special attention given to the behavior and role of the N atoms. The growth temperatures of interest are above 600 °C, far higher than the typical upper critical temperature of 500 °C in MBE. It was confirmed that 2 ML-thick InN wells can be frozen/inserted in GaN matrix at 620 °C, but it was found that N atoms at the growth front tend to selectively re-evaporate more quickly than In atoms at temperatures higher than 650 °C. As a result, the effective thickness of inserted InN wells in the GaN matrix at 660–670 °C were basically 1 ML or sub-ML, even though they were capped by a GaN barrier at the time of 2 ML “In+N” coverage. Furthermore, it was found that the N atoms located below In atoms in the dynamic atomic layer epitaxy growth front had remarkably weaker bonding to the +c-GaN surface.

  6. Face-Centered-Cubic Nanostructured Polymer Foams

    Science.gov (United States)

    Cui, C.; Baughman, R. H.; Liu, L. M.; Zakhidov, A. A.; Khayrullin, I. I.

    1998-03-01

    Beautifully iridescent polymer foams having Fm-3m cubic symmetry and periodicities on the scale of the wavelength of light have been synthesized by the templating of porous synthetic opals. These fabrication processes involve the filling of porous SiO2 opals (with typical cubic lattice parameters of 250 nm) with either polymers or polymer precursors, polymerization of the precursors if necessary, and removal of the fcc array of SiO2 balls to provide an all-polymer structure. The structures of these foams are similar to periodic minimal surfaces, although the Gaussian curvature can have both positive and negative values. Depending upon whether the internal surfaces of the opal are polymer filled or polymer coated, the polymer replica has either one or two sets of independent channels. We fill these channels with semiconductors, metals, or superconductors to provide electronic and optical materials with novel properties dependent on the nanoscale periodicity.

  7. Progress in theoretical approach to InGaN and InN epitaxy: In incorporation efficiency and structural stability

    Science.gov (United States)

    Kangawa, Yoshihiro; Ito, Tomonori; Koukitu, Akinori; Kakimoto, Koichi

    2014-10-01

    The surface stability, growth process, and structural stability of InGaN and InN are reviewed from a theoretical viewpoint. In 2001, a new theoretical approach based on an ab initio calculation was developed. This theoretical approach enables the investigation of the influence of growth conditions such as partial pressure and temperature on the surface stability. The theoretical approach is applied to the research on the In incorporation efficiency in InGaN grown on nonpolar and semipolar surfaces. The calculation results suggest that the N-H layer formed on such surfaces has a crucial role in In incorporation. Moreover, the structural stability of InN grown by pressurized-reactor MOVPE is reviewed. It was found by the theoretical approach that \\{ 1\\bar{1}\\bar{1}\\} facet formation causes the spontaneous formation of islands with the zinc-blende structure.

  8. Surface structure and surface kinetics of InN grown by plasma-assisted atomic layer epitaxy: A HREELS study

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, Ananta R., E-mail: aacharya@georgiasouthern.edu, E-mail: anantaach@gmail.com [Department of Physics, Georgia Southern University, Statesboro, Georgia 30460 (United States); Thoms, Brian D. [Department of Physics and Astronomy, Georgia State University, Atlanta, Georgia 30303 (United States); Nepal, Neeraj [American Association for Engineering Education, 1818 N Street NW, Washington, DC 20034 (United States); Eddy, Charles R. [Electronics Science and Technology Division, U.S. Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375 (United States)

    2015-03-15

    The surface bonding configuration and kinetics of hydrogen desorption from InN grown by plasma-assisted atomic layer epitaxy have been investigated. High resolution electron energy loss spectra exhibited loss peaks assigned to a Fuchs–Kliewer surface phonon, N-N and N-H surface species. The surface N-N vibrations are attributed to surface defects. The observation of N-H but no In-H surface species suggested N-terminated InN. Isothermal desorption data were best fit by the first-order desorption kinetics with an activation energy of (0.88 ± 0.06) eV and pre-exponential factor of (1.5 ± 0.5) × 10{sup 5 }s{sup −1}.

  9. High In Composition InGaN for InN Quantum Dot Intermediate Band Solar Cells

    Science.gov (United States)

    Gómez, Víctor J.; Rodriguez, Paul E. D. Soto; Kumar, Praveen; Calleja, Enrique; Nötzel, Richard

    2013-08-01

    We report a detailed study of the growth of InGaN by plasma assisted molecular beam epitaxy. The In composition is around 55% providing the optimum bandgap in the near-infrared spectral region of the matrix material of quantum dot (QD) intermediate band solar cells. The layer thickness is 80 nm for sufficient absorption. Optimum growth conditions are identified at elevated N flux and reduced growth temperature for minimized phase separation and smooth surface morphology. On these optimized InGaN layers, InN QDs are grown exhibiting small size and high density. Optical emission is observed from both the InGaN layer and InN QDs.

  10. Cubic Polynomials with Rational Roots and Critical Points

    Science.gov (United States)

    Gupta, Shiv K.; Szymanski, Waclaw

    2010-01-01

    If you want your students to graph a cubic polynomial, it is best to give them one with rational roots and critical points. In this paper, we describe completely all such cubics and explain how to generate them.

  11. Use of Pom Pons to Illustrate Cubic Crystal Structures.

    Science.gov (United States)

    Cady, Susan G.

    1997-01-01

    Describes a method that uses olefin pom pons to illustrate cubic crystal structure. Facilitates hands-on examination of different packing arrangements such as hexagonal close-packed and cubic close-packed structures. (JRH)

  12. Shape preserving rational bi-cubic function

    Directory of Open Access Journals (Sweden)

    Malik Zawwar Hussain

    2012-11-01

    Full Text Available The study is dedicated to the development of shape preserving interpolation scheme for monotone and convex data. A rational bi-cubic function with parameters is used for interpolation. To preserve the shape of monotone and convex data, the simple data dependent constraints are developed on these parameters in each rectangular patch. The developed scheme of this paper is confined, cheap to run and produce smooth surfaces.

  13. Cubic Lienard Equations with Quadratic Damping (Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    Yu-quan Wang; Zhu-jun Jing

    2002-01-01

    Applying Hopf bifurcation theory and qualitative theory, we show that the general cubic Lienard equations with quadratic damping have at most three limit cycles. This implies that the guess in which the system has at most two limit cycles is false. We give the sufficient conditions for the system has at most three limit cycles or two limit cycles. We present two examples with three limit cycles or two limit cycles by using numerical simulation.

  14. Individual electron and hole localization in submonolayer InN quantum sheets embedded in GaN

    OpenAIRE

    Feix, Felix; Flissikowski, Timur; Chèze, Caroline; Calarco, Raffaella; Grahn, Holger T.; Brandt, Oliver

    2016-01-01

    We investigate sub-monolayer InN quantum sheets embedded in GaN(0001) by temperature-dependent photoluminescence spectroscopy under both continuous-wave and pulsed excitation. Both the peak energy and the linewidth of the emission band associated with the quantum sheets exhibit an anomalous dependence on temperature indicative of carrier localization. Photoluminescence transients reveal a power law decay at low temperatures reflecting that the recombining electrons and holes occupy spatially ...

  15. Local atomic structure in cubic stabilized zirconia

    Energy Technology Data Exchange (ETDEWEB)

    Villella, P.; Conradson, S. D.; Espinosa-Faller, F. J.; Foltyn, S. R.; Sickafus, K. E.; Valdez, J. A.; Degueldre, C. A.

    2001-09-01

    X-ray-absorption fine structure measurements have been used to elucidate the local atomic structure of quaternary Zr, Y, Er, Ce/U cubic stabilized zirconia. These compounds display more complicated local environments than those reported for simpler binary systems. While the shortest cation-O distances are similar to those found in the binary cubic stabilized compounds, responding to the different sizes of the cations, we have identified large distortions in the first-shell oxygen distribution involving long, 2.8--3.2 {angstrom} cation-O distances that are similar to those found in the amorphous phase of zirconium. The cation-cation distributions are also found to be quite complicated (non-Gaussian) and element specific. The U-near neighbor distances are expanded relative to the Ce ions for which it substitutes, consistent with the larger size of the actinide, and the U-cation distribution is also more complicated. In terms of the effects of this substitution on the other cation sites, the local environment around Y is altered while the Zr and Er local environments remain unchanged. These results point out the importance of collective and correlated interactions between the different pairs of cations and the host lattice that are mediated by the local strain fields generated by the different cations. The presence of pair-specific couplings has not been commonly included in previous analyses and may have implications for the stabilization mechanisms of cubic zirconia.

  16. The special symplectic structure of binary cubics

    CERN Document Server

    Slupinski, Marcus

    2009-01-01

    Let $k$ be a field of characteristic not 2 or 3. Let $V$ be the $k$-space of binary cubic polynomials. The natural symplectic structure on $k^2$ promotes to a symplectic structure $\\omega$ on $V$ and from the natural symplectic action of $\\textrm{Sl}(2,k)$ one obtains the symplectic module $(V,\\omega)$. We give a complete analysis of this symplectic module from the point of view of the associated moment map, its norm square $Q$ (essentially the classical discriminant) and the symplectic gradient of $Q$. Among the results are a symplectic derivation of the Cardano-Tartaglia formulas for the roots of a cubic, detailed parameters for all $\\textrm{Sl}(2,k)$ and $\\textrm{Gl}(2,k)$-orbits, in particular identifying a group structure on the set of $\\textrm{Sl}(2,k)$-orbits of fixed nonzero discriminant, and a purely symplectic generalization of the classical Eisenstein syzygy for the covariants of a binary cubic. Such fine symplectic analysis is due to the special symplectic nature inherited from the ambient excepti...

  17. Method of synthesizing cubic system boron nitride

    Energy Technology Data Exchange (ETDEWEB)

    Yuzu, S.; Sumiya, H.; Degawa, J.

    1987-10-13

    A method is described for synthetically growing cubic system boron nitride crystals by using boron nitride sources, solvents for dissolving the boron nitride sources, and seed crystals under conditions of ultra-high pressure and high temperature for maintaining the cubic system boron nitride stable. The method comprises the following steps: preparing a synthesizing vessel having at least two chambers, arrayed in order in the synthesizing vessel so as to be heated according to a temperature gradient; placing the solvents having different eutectic temperatures in each chamber with respect to the boron nitride sources according to the temperature gradient; placing the boron nitride source in contact with a portion of each of the solvents heated at a relatively higher temperature and placing at least a seed crystal in a portion of each of the solvents heated at a relatively lower temperature; and growing at least one cubic system boron nitride crystal in each of the solvents in the chambers by heating the synthesizing vessel for establishing the temperature gradient while maintaining conditions of ultra-high pressure and high temperature.

  18. Structural and phonon properties of InN synthesized by ion implantation in SiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Graine, R. [Laboratoire LPR, Département de Physique, Faculté des Sciences, Université de Annaba, BP 12, Annaba 23000 (Algeria); Centre de Développement des Technologies Avancées, Unité de Recherche en Photonique et Optique (CDTA,URPO), Sétif 19000 (Algeria); Chemam, R., E-mail: che_raf@yahoo.fr [Laboratoire LPR, Département de Physique, Faculté des Sciences, Université de Annaba, BP 12, Annaba 23000 (Algeria); Gasmi, F.Z. [Laboratoire LPR, Département de Physique, Faculté des Sciences, Université de Annaba, BP 12, Annaba 23000 (Algeria); Muller, D. [ICube, Université de Strasbourg UdS and CNRS (UMR7357), 23 rue du Loess, 67037 Strasbourg (France); Schmerber, G. [Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 du CNRS, Université de Strasbourg UdS-ECPM, 23 Rue du Loess, 67034 Strasbourg (France)

    2015-11-30

    Ion-implantation is a powerful technique for the formation of compound semiconductor nanocrystal precipitates in a host medium. The aim is to elaborate quantum dots for device technology purposes. High dose (5.2 × 10{sup 16} ions/cm{sup 2}) implantations of Indium (In) and Nitrogen (N) ions have been performed in a 206 nm thick SiO{sub 2} layer thermally grown on < 111 > silicon. The implantation energies have been chosen from 12 to 180 keV to produce 5–10 at.% profiles overlapping at a mean depth of about 100 nm. Thermal treatments between 500 °C and 900 °C for different annealing times lead to the formation of InN nanometric precipitates and to cure the oxide defects. In addition, the In{sub 2}O{sub 3} and metallic indium phases have been observed. Their sizes, crystalline structures and depth distributions have been studied as a function of annealing temperature using grazing incidence X-ray diffraction, transmission electron microscopy, Rutherford back scattering spectrometry and Raman spectroscopy. - Highlights: • InN nanocrystals were formed by sequential ion implantation of In and N in SiO{sub 2}. • The In{sub 2}O{sub 3} and metallic indium phases have been found. • Redistribution of In occurs during post-implantation thermal annealing. • Three different InN family sizes were observed in the SiO{sub 2} layer.

  19. Vertically integrated (Ga, In)N nanostructures for future single photon emitters operating in the telecommunication wavelength range.

    Science.gov (United States)

    Winden, A; Mikulics, M; Grützmacher, D; Hardtdegen, H

    2013-10-11

    Important technological steps are discussed and realized for future room-temperature operation of III-nitride single photon emitters. First, the growth technology of positioned single pyramidal InN nanostructures capped by Mg-doped GaN is presented. The optimization of their optical characteristics towards narrowband emission in the telecommunication wavelength range is demonstrated. In addition, a device concept and technology was developed so that the nanostructures became singularly addressable. It was found that the nanopyramids emit in the telecommunication wavelength range if their size is chosen appropriately. A p-GaN contacting layer was successfully produced as a cap to the InN pyramids and the top p-contact was achievable using an intrinsically conductive polymer PEDOT:PSS, allowing a 25% increase in light transmittance compared to standard Ni/Au contact technology. Single nanopyramids were successfully integrated into a high-frequency device layout. These decisive technology steps provide a promising route to electrically driven and room-temperature operating InN based single photon emitters in the telecommunication wavelength range.

  20. Irradiation-induced defects in InN and GaN studied with positron annihilation

    Energy Technology Data Exchange (ETDEWEB)

    Reurings, Floris; Tuomisto, Filip [Department of Applied Physics, Aalto University, Espoo (Finland); Egger, Werner; Loewe, Benjamin [Institut fuer Angewandte Physik und Messtechnik, Universitaet der Bundeswehr Muenchen, Neubiberg (Germany); Ravelli, Luca [Dipartimento di Fisica, Universita degli studi di Trento, Povo (Italy); Sojak, Stanislav [Department of Nuclear Physics and Technology, Slovak University of Technology in Bratislava (Slovakia); Liliental-Weber, Zuzanna; Jones, Rebecca E.; Yu, Kin M.; Walukiewicz, Wladek [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA (United States); Schaff, William J. [Department of Electrical and Computer Engineering, Cornell University, Ithaca, NY (United States)

    2010-05-15

    We use positron annihilation to study 2-MeV {sup 4}He{sup +} irradiated and subsequently rapid-thermal-annealed InN grown by molecular-beam epitaxy and GaN grown by metal-organic chemical-vapour deposition. The irradiation fluences were in the range 5 x 10{sup 14}-2 x 10{sup 16}cm{sup -2}. In vacancies are introduced in the irradiation at a low rate of 100 cm{sup -1}, with their concentration saturating in the mid-10{sup 17} cm{sup -3} range at an irradiation fluence of 2 x 10{sup 15} cm{sup -2}. The annealing, performed at temperatures between 425 and 475 C, is observed to result in an inhomogeneous redistribution of the In vacancies. The behaviour is opposite to GaN, where Ga vacancies are introduced at a much higher rate of 3600 cm{sup -1} showing no detectable saturation. About half of the Ga vacancies are found to recover in the annealing, in agreement with previous studies, while the remaining Ga vacancies undergo no spatial redistribution. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  1. Molten salt-based growth of bulk GaN and InN for substrates.

    Energy Technology Data Exchange (ETDEWEB)

    Waldrip, Karen Elizabeth

    2007-08-01

    An atmospheric pressure approach to growth of bulk group III-nitrides is outlined. Native III-nitride substrates for optoelectronic and high power, high frequency electronics are desirable to enhance performance and reliability of these devices; currently, these materials are available in research quantities only for GaN, and are unavailable in the case of InN. The thermodynamics and kinetics of the reactions associated with traditional crystal growth techniques place these activities on the extreme edges of experimental physics. The novel techniques described herein rely on the production of the nitride precursor (N{sup 3-}) by chemical and/or electrochemical methods in a molten halide salt. This nitride ion is then reacted with group III metals in such a manner as to form the bulk nitride material. The work performed during the period of funding (February 2006-September 2006) focused on establishing that mass transport of GaN occurs in molten LiCl, the construction of a larger diameter electrochemical cell, the design, modification, and installation of a made-to-order glove box (required for handling very hygroscopic LiCl), and the feasibility of using room temperature molten salts to perform nitride chemistry experiments.

  2. RESUSPENSION OF FINE SEDIMENT IN RESERVOIRS A CASE STUDY OF THE LOWER INN RIVER

    Institute of Scientific and Technical Information of China (English)

    Thomas ELSNER; Sven HARTMANN

    2001-01-01

    The Inn river, major tributary of the Danube river in Germany, has its origin in the higher alpine region of Switzerland and Austria. Mainly for flood management reasons and the extensive production of hydropower based electricity it was fixed with massive embankments and subdivided into a chain of reservoirs. Caused by severe amounts of sediments, mostly fine material as suspended load, a significant sedimentation of the reservoirs takes place. Different strategies are known and investigated to extend the life-cycle of the reservoirs and the efficient use of the turbines. During the past decades parts of the reservoirs turned into ecologically valuable habitats which had to be excluded from e.g. flushing operations and are protected areas nowadays. In the meantime ecologists had to realize that the value of those ecosystems is declining as the result of further aggradation of the depositions leading to a new but static condition. Measures are discussed to stimulate dynamic changes of the sand bars avoiding their stabilization by vegetation like bushes and trees. Basic ideas of the concept and the 2d-model to simulate and optimize engineering solutions are described respecting ecological restrictions.

  3. Air annealing induced transformation of cubic CdSe microspheres into hexagonal nanorods and micro-pyramids

    Energy Technology Data Exchange (ETDEWEB)

    Kale, Rohidas B., E-mail: rb_kale@yahoo.co.in [Department of Physics, Institute of Science, Mumbai 400032, M.S. (India); Lu, Shih-Yuan, E-mail: sylu@mx.nthu.edu.tw [Department of Chemical Engineering, National Tsing-Hua University, Hsin-Chu 30013, Taiwan (China)

    2015-08-15

    Highlights: • Nanocrystalline CdSe thin films were deposited using inexpensive CBD method. • Air annealing induced structural and interesting morphological transformation. • The as-deposited CdSe thin films showed a blue shift in its optical spectra. • The films showed a red shift in their optical spectra after annealing. - Abstract: CdSe thin films have been deposited onto glass substrates using a chemical bath deposition method at relatively low temperatures (40 °C). The precursors used for the deposition of the thin films are cadmium nitrate hexahydrate, freshly prepared sodium selenosulfate solution and aqueous ammonia solution as a complex as well as pH adjusting reagent. In order to study the influence of air annealing on their physicochemical properties, the as-deposited CdSe thin films were further annealed at 200 °C and 400 °C for 3 h in air atmosphere. Significant changes in the morphology and photonic properties were clearly observed after the thermal annealing of the CdSe thin films. The as-deposited CdSe films grow with the cubic phase that transforms into mixed cubic and hexagonal wurtzite phase with improved crystalline quality of the films after the air annealing. Morphological observation reveals that the as-deposited thin films grow with multilayer that consists of network or mesh like structure, uniformly deposited on the glass substrate over which microspheres are uniformly distributed. After air annealing, CdSe nanorods emerged from the microspheres along with conversion of few microspheres into micro-pyramids. The UV–visible study illustrates that the as-deposited thin film shows blue shifts in its optical spectrum and the spectrum was red-shifted after annealing the CdSe thin films. The band gap of the CdSe thin films were found to be decreased after the thermal treatment.

  4. The impact of weak synoptic forcing on the valley-wind circulation in the Alpine Inn Valley

    Science.gov (United States)

    Zängl, Günther

    2009-09-01

    This paper investigates the impact of weak synoptic-scale forcing on the thermally induced valley-wind circulation in the Alpine Inn Valley and one of its largest tributaries, the Wipp Valley. To this end, high-resolution numerical simulations with realistic topography but idealized large-scale atmospheric conditions are performed. The large-scale flow has a speed increasing linearly from 5 m s-1 at sea level to 12.5 m s-1 at tropopause level, but its direction is varied between each experiment. For reference, an experiment without large-scale winds is conducted as well. The results indicate that the sensitivity to ambient flow forcing differs substantially between the Inn Valley and the Wipp Valley. The valley-wind circulation of the Inn Valley is found to be fairly robust against weak ambient forcing, changing by a much smaller amount than the along-valley component of the imposed large-scale flow. The valley wind tends to be intensified (weakened) when the ambient flow is aligned with (opposite to) the local valley orientation. However, the flow response is complicated by larger-scale interactions of the ambient flow with the Alpine massif. Most notably, northerly and northwesterly flow is deflected around the Alps, leading to the formation of a low-level jet along the northern edge of the Alps which in turn affects the valley-wind circulation in the lower Inn Valley. For the Wipp Valley, which is oriented approximately normal to the Alpine crest line and constitutes a deep gap in the Alpine crest, two distinctly different flow regimes are found depending on whether the large-scale flow has a significant southerly component or not. In the absence of a southerly flow component, the valley-wind circulation is similarly robust against ambient forcing as in the Inn Valley, with a fairly weak response of the local wind speeds. However, southerly ambient flow tends to force continuous downvalley (southerly) wind in the Wipp Valley. The flow dynamics can then be

  5. Cherenkov and Scintillation Properties of Cubic Zirconium

    Science.gov (United States)

    Christl, M.J.; Adams, J.H.; Parnell, T.A.; Kuznetsov, E.N.

    2008-01-01

    Cubic zirconium (CZ) is a high index of refraction (n =2.17) material that we have investigated for Cherenkov counter applications. Laboratory and proton accelerator tests of an 18cc sample of CZ show that the expected fast Cherenkov response is accompanied by a longer scintillation component that can be separated by pulse shaping. This presents the possibility of novel particle spectrometers which exploits both properties of CZ. Other high index materials being examined for Cherenkov applications will be discussed. Results from laboratory tests and an accelerator exposure will be presented and a potential application in solar energetic particle instruments will be discussed

  6. Tachyon Vacuum in Cubic Superstring Field Theory

    CERN Document Server

    Erler, Theodore

    2008-01-01

    In this paper we give an exact analytic solution for tachyon condensation in the modified (picture 0) cubic superstring field theory. We prove the absence of cohomology and, crucially, reproduce the correct value for the D-brane tension. The solution is surprising for two reasons: First, the existence of a tachyon vacuum in this theory has not been definitively established in the level expansion. Second, the solution {\\it vanishes} in the GSO$(-)$ sector, implying a ``tachyon vacuum'' solution exists even for a {\\it BPS} D-brane.

  7. Generalized fairing algorithm of parametric cubic splines

    Institute of Scientific and Technical Information of China (English)

    WANG Yuan-jun; CAO Yuan

    2006-01-01

    Kjellander has reported an algorithm for fairing uniform parametric cubic splines. Poliakoff extended Kjellander's algorithm to non-uniform case. However, they merely changed the bad point's position, and neglected the smoothing of tangent at bad point. In this paper, we present a fairing algorithm that both changed point's position and its corresponding tangent vector. The new algorithm possesses the minimum property of energy. We also proved Poliakoff's fairing algorithm is a deduction of our fairing algorithm. Several fairing examples are given in this paper.

  8. Fractal Symmetries: Ungauging the Cubic Code

    CERN Document Server

    Williamson, Dominic J

    2016-01-01

    Gauging is a ubiquitous tool in many-body physics. It allows one to construct highly entangled topological phases of matter from relatively simple phases and to relate certain characteristics of the two. Here we develop a gauging procedure for general submanifold symmetries of Pauli Hamiltonians, including symmetries of fractal type. We show a relation between the pre- and post- gauging models and use this to construct short range entangled phases with fractal like symmetries, one of which is mapped to the cubic code by the gauging.

  9. The Exact Limit of Some Cubic Towers

    DEFF Research Database (Denmark)

    Anbar Meidl, Nurdagül; Beelen, Peter; Nguyen, Nhut

    2016-01-01

    Recently, a new explicit tower of function fields was introduced by Bassa, Beelen, Garcia and Stichtenoth (BBGS). This resulted in currently the best known lower bound for Ihara’s constant in the case of non-prime finite fields. In particular over cubic fields, the tower’s limit is at least as good...... as Zink’s bound; i.e. λ(BBGS/Fq3 ) ≥ 2(q2 - 1)/(q + 2). In this paper, the exact value of λ(BBGS/Fq3 ) is computed. We also settle a question stated by Ihara....

  10. Competing structural instabilities in cubic perovskites

    CERN Document Server

    Vanderbilt, D

    1994-01-01

    We study the antiferrodistortive instability and its interaction with ferroelectricity in cubic perovskite compounds. Our first-principles calculations show that coexistence of both instabilities is very common. We develop a first-principles scheme to study the thermodynamics of these compounds when both instabilities are present, and apply it to SrTiO$_3$. We find that increased pressure enhances the antiferrodistortive instability while suppressing the ferroelectric one. Moreover, the presence of one instability tends to suppress the other. A very rich $P$--$T$ phase diagram results.

  11. Thin films for material engineering

    Science.gov (United States)

    Wasa, Kiyotaka

    2016-07-01

    Thin films are defined as two-dimensional materials formed by condensing one by one atomic/molecular/ionic species of matter in contrast to bulk three-dimensional sintered ceramics. They are grown through atomic collisional chemical reaction on a substrate surface. Thin film growth processes are fascinating for developing innovative exotic materials. On the basis of my long research on sputtering deposition, this paper firstly describes the kinetic energy effect of sputtered adatoms on thin film growth and discusses on a possibility of room-temperature growth of cubic diamond crystallites and the perovskite thin films of binary compound PbTiO3. Secondly, high-performance sputtered ferroelectric thin films with extraordinary excellent crystallinity compatible with MBE deposited thin films are described in relation to a possible application for thin-film MEMS. Finally, the present thin-film technologies are discussed in terms of a future material science and engineering.

  12. Beaulieu-Boycott-Innes syndrome: an intellectual disability syndrome with characteristic facies.

    Science.gov (United States)

    Casey, Jillian; Jenkinson, Allan; Magee, Alex; Ennis, Sean; Monavari, Ahmad; Green, Andrew; Lynch, Sally A; Crushell, Ellen; Hughes, Joanne

    2016-10-01

    We report a female child from an Irish Traveller family presenting with severe intellectual disability, dysmorphic features, renal anomalies, dental caries and cyclical vomiting. Current health issues include global developmental delay, mild concentric left ventricular hypertrophy, dental malocclusion and caries and a single duplex left kidney. The proband and her mother also have multiple epiphyseal dysplasia. Whole-exome sequencing was performed to identify the underlying genetic cause. DNA from the proband was enriched with the Agilent Sure Select v5 Exon array and sequenced on an Illumina HiSeq. Rare homozygous variants were prioritized. Whole-exome sequencing identified three linked homozygous missense variants in THOC6 (c.298T>A, p.Trp100Arg; c.700G>C, p.Val234Leu; c.824G>A, p.Gly275Asp) as the likely cause of this child's intellectual disability syndrome, resulting in a molecular diagnosis of Beaulieu-Boycott-Innes syndrome (BBIS). This is the first report of BBIS in Europe. BBIS has been reported previously in two Hutterite families and one Saudi family. A review of all patients to date shows a relatively homogenous phenotype. Core clinical features include low birth weight with subsequent growth failure, short stature, intellectual disability with language delay, characteristic facies, renal anomalies and dental malocclusion with caries. Some patients also have cardiac defects. All patients show characteristic dysmorphic facial features including a tall forehead with high anterior hairline and deep-set eyes with upslanting palpebral fissures. The coexistence of intellectual disability together with these characteristic facies should provide a diagnostic clue for BBIS during patient evaluation.

  13. Metastable cubic tin sulfide: A novel phonon-stable chiral semiconductor

    Directory of Open Access Journals (Sweden)

    Jonathan M. Skelton

    2017-03-01

    Full Text Available SnS is a semiconductor of interest for next-generation thin-film photovoltaic devices. The ground-state phase is layered with an orthorhombic (Pnma crystal structure. Anisotropy in the electrical properties has been linked to the low performance of SnS solar cells. These factors make a new cubic phase (π-SnS of immense practical interest. We report the properties of the recently solved crystal structure (P213 of cubic SnS from first-principles. π-SnS is phonon stable, in contrast to the zincblende phase, and lies 2.2 kJ/mol above the ground state. It features an electronic bandgap of 1.7 eV with a chiral modulation of the band-edge states.

  14. Rheological properties of Cubic colloidal suspensions

    Science.gov (United States)

    Boromand, Arman; Maia, Joao

    2016-11-01

    Colloidal and non-colloidal suspensions are ubiquitous in many industrial application. There are numerous studies on these systems to understand and relate their complex rheological properties to their microstructural evolution under deformation. Although most of the experimental and simulation studies are centered on spherical particles, in most of the industrial applications the geometry of the colloidal particles deviate from the simple hard sphere and more complex geometries exist. Recent advances in microfabrication paved the way to fabricate colloidal particles with complex geometries for applications in different areas such as drug delivery where the fundamental understanding of their dynamics has remained unexplored. In this study, using dissipative particle dynamics, we investigate the rheological properties of cubic (superball) particles which are modeled as the cluster of core-modified DPD particles. Explicit representation of solvent particles in the DPD scheme will conserve the full hydrodynamic interactions between colloidal particles. Rheological properties of these cubic suspensions are investigated in the dilute and semi-dilute regimes. The Einstein and Huggins coefficients for these particles with different superball exponent will be calculate which represent the effect of single particle's geometry and multibody interactions on viscosity, respectively. The response of these suspensions is investigated under simple shear and oscillatory shear where it is shown that under oscillation these particles tend to form crystalline structure giving rise to stronger shear-thinning behavior recently measured experimentally.

  15. Local lattice environment of indium in GaN, AlN, and InN; Lokale Gitterumgebung von Indium in GaN, AlN und InN

    Energy Technology Data Exchange (ETDEWEB)

    Penner, J.

    2007-12-20

    After an introduction to the physical properties of the nitrides, their preparation, and the state of studies on the implantation in the nitrides the experimental method (PAC) applied in this thesis and the data analysis are presented. The next chapter describes then the applied materials and the sample preparation. The following chapters contain the PAC measurements on the annealing behaviout of GaN, AlN, and InN after the implantation as well as dose- and temperature dependent PAC studies. Finally the most important results are summarized.

  16. Fabrication of a-plane InN nanostructures on patterned a-plane GaN template by ECR-MBE

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Tsutomu; Yamashita, Shuhei [Department of Photonics, Ritsumeikan University, Kusatsu, Shiga (Japan); Yamaguchi, Tomohiro [Ritsumeikan Global Innovation Research Organization (R-GIRO), Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga (Japan); Yoon, Euijoon [Department of Materials Science and Engineering, WCU Hybrid Materials Program, Seoul National University, Mt56-1, Sillim-dong, Gwanak-gu, Seoul (Korea, Republic of); Nanishi, Yasushi [Ritsumeikan Global Innovation Research Organization (R-GIRO), Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga (Japan); Department of Materials Science and Engineering, WCU Hybrid Materials Program, Seoul National University, Mt56-1, Sillim-dong, Gwanak-gu, Seoul (Korea, Republic of)

    2012-03-15

    a-plane InN nanostructures were fabricated on a hole-patterned a-plane GaN template by electron-cyclotron-resonance plasma-excited molecular beam epitaxy (ECR-MBE). The growth temperature should be optimized to realize precise nucleation at the patterned holes with sufficient In desorption and a sufficiently long In migration length. Polarity determination clearly revealed that a-plane InN crystals have an anisotropic growth morphology. The InN growth rate in the N-polar [000-1] direction is higher than those in the In-polar [0001] and [1-100] directions. a-plane InN nano-walls were fabricated by exploiting the different the growth rates in the left angle 0001 right angle and left angle 1-100 right angle directions. SEM image of position-controlled a-plane InN nanostructures grown by ECR-MBE on a hole-patterned a-plane GaN template. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  17. All unitary cubic curvature gravities in D dimensions

    Energy Technology Data Exchange (ETDEWEB)

    Sisman, Tahsin Cagri; Guellue, Ibrahim; Tekin, Bayram, E-mail: sisman@metu.edu.tr, E-mail: e075555@metu.edu.tr, E-mail: btekin@metu.edu.tr [Department of Physics, Middle East Technical University, 06531 Ankara (Turkey)

    2011-10-07

    We construct all the unitary cubic curvature gravity theories built on the contractions of the Riemann tensor in D-dimensional (anti)-de Sitter spacetimes. Our construction is based on finding the equivalent quadratic action for the general cubic curvature theory and imposing ghost and tachyon freedom, which greatly simplifies the highly complicated problem of finding the propagator of cubic curvature theories in constant curvature backgrounds. To carry out the procedure we have also classified all the unitary quadratic models. We use our general results to study the recently found cubic curvature theories using different techniques and the string generated cubic curvature gravity model. We also study the scattering in critical gravity and give its cubic curvature extensions.

  18. Advances in modeling semiconductor epitaxy: Contributions of growth orientation and surface reconstruction to InN metalorganic vapor phase epitaxy

    Science.gov (United States)

    Kusaba, Akira; Kangawa, Yoshihiro; Kempisty, Pawel; Shiraishi, Kenji; Kakimoto, Koichi; Koukitu, Akinori

    2016-12-01

    We propose a newly improved thermodynamic analysis method that incorporates surface energies. The new theoretical approach enables us to investigate the effects of the growth orientation and surface reconstruction. The obtained knowledge would be indispensable for examining the preferred growth conditions in terms of the contribution of the surface state. We applied the theoretical approach to study the growth processes of InN(0001) and (000\\bar{1}) by metalorganic vapor phase epitaxy. Calculation results reproduced the difference in optimum growth temperature. That is, we successfully developed a new theoretical approach that can predict growth processes on various growth surfaces.

  19. Direct immobilization of enzymes in GaN and InN nanocolumns: The urease case study

    Science.gov (United States)

    Sofikiti, N.; Chaniotakis, N.; Grandal, J.; Utrera, M.; Sanchez-Garcia, M. A.; Calleja, E.; Iliopoulos, E.; Georgakilas, A.

    2009-09-01

    In this work, the development of potentiometric urea biosensors through the entrapment of urease enzyme within the cavities of nanocolumnar GaN and InN wurtzite semiconductor substrates, is being described. The biosensing capabilities of these materials are compared with biosensors based on the corresponding flat surfaces, in order to check the increased sensitivity and enzyme stabilization properties expected from the nanocolumns. The obtained results proved that the electrochemically active nanocolumns serve both as highly sensitive transducer, as well as stabilizing nanoenvironment within which urease retains its catalytic activity for a prolonged period of time.

  20. Cubic meter volume optical coherence tomography

    Science.gov (United States)

    WANG, ZHAO; POTSAID, BENJAMIN; CHEN, LONG; DOERR, CHRIS; LEE, HSIANG-CHIEH; NIELSON, TORBEN; JAYARAMAN, VIJAYSEKHAR; CABLE, ALEX E.; SWANSON, ERIC; FUJIMOTO, JAMES G.

    2017-01-01

    Optical coherence tomography (OCT) is a powerful three-dimensional (3D) imaging modality with micrometer-scale axial resolution and up to multi-GigaVoxel/s imaging speed. However, the imaging range of high-speed OCT has been limited. Here, we report 3D OCT over cubic meter volumes using a long coherence length, 1310 nm vertical-cavity surface-emitting laser and silicon photonic integrated circuit dual-quadrature receiver technology combined with enhanced signal processing. We achieved 15 µm depth resolution for tomographic imaging at a 100 kHz axial scan rate over a 1.5 m range. We show 3D macroscopic imaging examples of a human mannequin, bicycle, machine shop gauge blocks, and a human skull/brain model. High-bandwidth, meter-range OCT demonstrates new capabilities that promise to enable a wide range of biomedical, scientific, industrial, and research applications. PMID:28239628

  1. Black holes in Einsteinian cubic gravity

    CERN Document Server

    Hennigar, Robie A

    2016-01-01

    Using numerical and perturbative methods, we construct the first examples of black hole solutions in Einsteinian cubic gravity and study their thermodynamics. Focusing first on four dimensional solutions, we show that these black holes have a novel equation of state in which the pressure is a quadratic function of the temperature. Despite this, they undergo a first order phase transition with associated van der Waals behaviour. We then construct perturbative solutions for general $D \\ge 5$ and study the properties of these solutions for $D=5$ and $D=6$ in particular. We find novel examples of zeroth order phase transitions and find super-entropic behaviour over a large portion of the parameter space. We analyse the specific heat, determining that the black holes are thermodynamically stable over large regions of parameter space.

  2. Triangulation of cubic panorama for view synthesis.

    Science.gov (United States)

    Zhang, Chunxiao; Zhao, Yan; Wu, Falin

    2011-08-01

    An unstructured triangulation approach, new to our knowledge, is proposed to apply triangular meshes for representing and rendering a scene on a cubic panorama (CP). It sophisticatedly converts a complicated three-dimensional triangulation into a simple three-step triangulation. First, a two-dimensional Delaunay triangulation is individually carried out on each face. Second, an improved polygonal triangulation is implemented in the intermediate regions of each of two faces. Third, a cobweblike triangulation is designed for the remaining intermediate regions after unfolding four faces to the top/bottom face. Since the last two steps well solve the boundary problem arising from cube edges, the triangulation with irregular-distribution feature points is implemented in a CP as a whole. The triangular meshes can be warped from multiple reference CPs onto an arbitrary viewpoint by face-to-face homography transformations. The experiments indicate that the proposed triangulation approach provides a good modeling for the scene with photorealistic rendered CPs.

  3. Black holes in a cubic Galileon universe

    CERN Document Server

    Babichev, Eugeny; Lehébel, Antoine; Moskalets, Tetiana

    2016-01-01

    We find and study the properties of black hole solutions for a subclass of Horndeski theory including the cubic Galileon term. The theory under study has shift symmetry but not reflection symmetry for the scalar field. The Galileon is assumed to have linear time dependence characterized by a velocity parameter. We give analytic 3-dimensional solutions that are akin to the BTZ solutions but with a non-trivial scalar field that modifies the effective cosmological constant. We then study the 4-dimensional asymptotically flat and de Sitter solutions. The latter present three different branches according to their effective cosmological constant. For two of these branches, we find families of black hole solutions, parametrized by the velocity of the scalar field. These spherically symmetric solutions, obtained numerically, are different from GR solutions close to the black hole event horizon, while they have the same de-Sitter asymptotic behavior. The velocity parameter represents black hole primary hair.

  4. Finite element differential forms on cubical meshes

    CERN Document Server

    Arnold, Douglas N

    2012-01-01

    We develop a family of finite element spaces of differential forms defined on cubical meshes in any number of dimensions. The family contains elements of all polynomial degrees and all form degrees. In two dimensions, these include the serendipity finite elements and the rectangular BDM elements. In three dimensions they include a recent generalization of the serendipity spaces, and new H(curl) and H(div) finite element spaces. Spaces in the family can be combined to give finite element subcomplexes of the de Rham complex which satisfy the basic hypotheses of the finite element exterior calculus, and hence can be used for stable discretization of a variety of problems. The construction and properties of the spaces are established in a uniform manner using finite element exterior calculus.

  5. Capturing dynamic cation hopping in cubic pyrochlores

    Science.gov (United States)

    Brooks Hinojosa, Beverly; Asthagiri, Aravind; Nino, Juan C.

    2011-08-01

    In direct contrast to recent reports, density functional theory predicts that the most stable structure of Bi2Ti2O7 pyrochlore is a cubic Fd3¯m space group by accounting for atomic displacements. The displaced Bi occupies the 96g(x,x,z) Wyckoff position with six equivalent sites, which create multiple local minima. Using nudged elastic band method, the transition states of Bi cation hopping between equivalent minima were investigated and an energy barrier between 0.11 and 0.21 eV was determined. Energy barriers associated with the motion of Bi between equivalent sites within the 96g Wyckoff position suggest the presence of dielectric relaxation in Bi2Ti2O7.

  6. On the plane-wave cubic vertex

    CERN Document Server

    Lucietti, J; Sinha, A K; Lucietti, James; Schäfer-Nameki, Sakura; Sinha, Aninda

    2004-01-01

    The exact bosonic Neumann matrices of the cubic vertex in plane-wave light-cone string field theory are derived using the contour integration techniques developed in our earlier paper. This simplifies the original derivation of the vertex. In particular, the Neumann matrices are written in terms of \\mu-deformed Gamma-functions, thus casting them into a form that elegantly generalizes the well-known flat-space solution. The asymptotics of the \\mu-deformed Gamma-functions allow one to determine the large-\\mu behaviour of the Neumann matrices including exponential corrections. We provide an explicit expression for the first exponential correction and make a conjecture for the subsequent exponential correction terms.

  7. Polarization conversion in cubic Raman crystals

    Science.gov (United States)

    McKay, Aaron; Sabella, Alexander; Mildren, Richard P.

    2017-01-01

    Nonlinear conversion of unpolarized beams to lower frequencies is generally inefficient in c(2) materials, as it is challenging to achieve phase-matching for input ordinary and extraordinary beams simultaneously in the normal dispersion regime. Here, we show that cubic Raman crystals having doubly and triply degenerate (E and F type) modes provide a method for efficient nonlinear frequency downconversion of an unpolarized beam and yield a linearly polarized output state. Using Mueller calculus, optimal crystal directions for such polarization conversion are determined. Using diamond, an example of an F-class Raman crystal, we have verified that such conversion is possible with near quantum-defect-limited slope efficiency and a linear polarization contrast of more than 23.9 dB. PMID:28169327

  8. On the Stability of Cubic Galileon Accretion

    CERN Document Server

    Bergliaffa, Santiago P E

    2016-01-01

    We examine the stability of steady-state galileon accretion for the case of a Schwarzshild black hole. Considering the galileon action up to the cubic term in a static and spherically symmetric background we obtain the general solution for the equation of motion which is divided in two branches. By perturbing this solution we define an effective metric which determines the propagation of fluctuations. In this general picture we establish the position of the sonic horizon together with the matching condition of the two branches on it. Restricting to the case of a Schwarzschild background, we show, via the analysis of the energy of the perturbations and its time derivative, that the accreting field is linearly stable.

  9. Systematic study on dynamic atomic layer epitaxy of InN on/in +c-GaN matrix and fabrication of fine-structure InN/GaN quantum wells: Role of high growth temperature

    Science.gov (United States)

    Yoshikawa, Akihiko; Kusakabe, Kazuhide; Hashimoto, Naoki; Hwang, Eun-Sook; Imai, Daichi; Itoi, Takaomi

    2016-12-01

    The growth kinetics and properties of nominally 1-ML (monolayer)-thick InN wells on/in +c-GaN matrix fabricated using dynamic atomic layer epitaxy (D-ALEp) by plasma-assisted molecular beam epitaxy were systematically studied, with particular attention given to the effects of growth temperature. Attention was also given to how and where the ˜1-ML-thick InN layers were frozen or embedded on/in the +c-GaN matrix. The D-ALEp of InN on GaN was a two-stage process; in the 1st stage, an "In+N" bilayer/monolayer was formed on the GaN surface, while in the 2nd, this was capped by a GaN barrier layer. Each process was monitored in-situ using spectroscopic ellipsometry. The target growth temperature was above 620 °C and much higher than the upper critical epitaxy temperature of InN (˜500 °C). The "In+N" bilayer/monolayer tended to be an incommensurate phase, and the growth of InN layers was possible only when they were capped with a GaN layer. The InN layers could be coherently inserted into the GaN matrix under self-organizing and self-limiting epitaxy modes. The growth temperature was the most dominant growth parameter on both the growth process and the structure of the InN layers. Reflecting the inherent growth behavior of D-ALEp grown InN on/in +c-GaN at high growth temperature, the embedded InN layers in the GaN matrix were basically not full-ML in coverage, and the thickness of sheet-island-like InN layers was essentially either 1-ML or 2-ML. It was found that these InN layers tended to be frozen at the step edges on the GaN and around screw-type threading dislocations. The InN wells formed type-I band line-up heterostructures with GaN barriers, with exciton localization energies of about 300 and 500 meV at 15 K for the 1-ML and 2-ML InN wells, respectively.

  10. Shape preserving rational cubic spline for positive and convex data

    Directory of Open Access Journals (Sweden)

    Malik Zawwar Hussain

    2011-11-01

    Full Text Available In this paper, the problem of shape preserving C2 rational cubic spline has been proposed. The shapes of the positive and convex data are under discussion of the proposed spline solutions. A C2 rational cubic function with two families of free parameters has been introduced to attain the C2 positive curves from positive data and C2 convex curves from convex data. Simple data dependent constraints are derived on free parameters in the description of rational cubic function to obtain the desired shape of the data. The rational cubic schemes have unique representations.

  11. Ciudad, televisión y fantasías: Vírgenes del Sol Inn Cabaret de Alexis Figueroa City, Television and Fantasies: Alexis Figueroa's Vírgenes del Sol Inn Cabaret

    Directory of Open Access Journals (Sweden)

    Magda Sepúlveda Eriz

    2008-12-01

    Full Text Available Vírgenes del Sol Inn Cabaret (1986, del poeta chileno Alexis Figueroa, recrea la complejidad de las relaciones en la cultura del tele-ver, en una sociedad tercermundista autoritaria y neoliberal. Con el cercenamiento del espacio público de la calle, la televisión ocupa su lugar e impone su única coherencia, esta es la rentabilidad comercial. Por ello, la ciudad bajo la influencia de la televisión es representada por Figueroa a través de la metáfora del cabaret, un territorio donde los movimientos principales son mostrarse y ver. De esta forma, las reflexiones del poemario giran en torno al comercio de las subjetividades y el consecuente aprendizaje del rol de actriz o público.The Chilean poet Alexis Figueroa's Vírgenes del Sol Inn Cabaret (1986 recreates the complexity of relationships in the television culture, in Latin American authoritarian and neoliberal society. With the curtailing of public space in the streets, the television usurps its place and imposes its one and only coherence: profit. This is why the city under the TV's influence is depicted by Figueroa using a cabaret as metaphor. A location where we find two main actions: showing off and watching. In this way, the reflections of the poem revolve around marketing subjectivities and subsequently learning from acting or watching.

  12. Characterization, Microstructure, and Dielectric properties of cubic pyrochlore structural ceramics

    KAUST Repository

    Li, Yangyang

    2013-05-01

    The (BMN) bulk materials were sintered at 1050°C, 1100°C, 1150°C, 1200°C by the conventional ceramic process, and their microstructure and dielectric properties were investigated by Scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Transmission electron microscopy (TEM) (including the X-ray energy dispersive spectrometry EDS and high resolution transmission electron microscopy HRTEM) and dielectric impedance analyzer. We systematically investigated the structure, dielectric properties and voltage tunable property of the ceramics prepared at different sintering temperatures. The XRD patterns demonstrated that the synthesized BMN solid solutions had cubic phase pyrochlore-type structure when sintered at 1050°C or higher, and the lattice parameter (a) of the unit cell in BMN solid solution was calculated to be about 10.56Å. The vibrational peaks observed in the Raman spectra of BMN solid solutions also confirmed the cubic phase pyrochlore-type structure of the synthesized BMN. According to the Scanning Electron Microscope (SEM) images, the grain size increased with increasing sintering temperature. Additionally, it was shown that the densities of the BMN ceramic tablets vary with sintering temperature. The calculated theoretical density for the BMN ceramic tablets sintered at different temperatures is about 6.7521 . The density of the respective measured tablets is usually amounting more than 91% and 5 approaching a maximum value of 96.5% for sintering temperature of 1150°C. The microstructure was investigated by using Scanning Transmission Electron Microscope (STEM), X-ray diffraction (XRD). Combined with the results obtained from the STEM and XRD, the impact of sintering temperature on the macroscopic and microscopic structure was discussed. The relative dielectric constant ( ) and dielectric loss ( ) of the BMN solid solutions were measured to be 161-200 and (at room temperature and 100Hz-1MHz), respectively. The BMN solid

  13. Effect of post annealing on MgO thin film prepared on silicon(001) substrate in high oxygen pressure and high substrate temperature by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kaneko, Satoru; Akiyama, Kensuke; Ito, Takeshi; Yasui, Manabu; Ozawa, Takeshi; Soga, Masayasu; Motoizumi, Yu [Kanagawa Industrial Technology Center, Kanagawa Prefectural Government, 705-1 Shimo-Imaizumi, Ebina, Kanagawa 243-0435 (Japan); Yoshimoto, Mamoru, E-mail: satoru@kanagawa-iri.go.jp [Department of Innovative and Engineered Materials, Tokyo Institute of Technology, 4259 Nagatsuda, Midori-ku, Yokohama, Kanagawa 226-8503 (Japan)

    2011-03-15

    Epitaxial growth of MgO was verified with the relation of MgO(100) parallel to Si(100) (cubic on cubic growth) even with a large mismatch of lattice constants {approx} 22%, instead of 9% mismatch in 45{sup 0} rotation growth. MgO films prepared at higher deposition temperature showed (001) preferred orientation on Si(001) substrate. After post-annealing the MgO thin films, the pole figure of X-ray diffraction verified the epitaxial growth of cubic on cubic relation. Fe{sub 3}Si thin film was deposited on Si(001) substrate with the MgO film as buffer layer.

  14. Distorted asymmetric cubic nanostructure of soluble fullerene crystals in efficient polymer:fullerene solar cells.

    Science.gov (United States)

    Kim, Youngkyoo; Nelson, Jenny; Zhang, Tong; Cook, Steffan; Durrant, James R; Kim, Hwajeong; Park, Jiho; Shin, Minjung; Nam, Sungho; Heeney, Martin; McCulloch, Iain; Ha, Chang-Sik; Bradley, Donal D C

    2009-09-22

    We found that 1-(3-methoxycarbonyl)propyl-1-phenyl-(6,6)C(61) (PCBM) molecules make a distorted asymmetric body-centered cubic crystal nanostructure in the bulk heterojunction films of reigoregular poly(3-hexylthiophene) and PCBM. The wider angle of distortion in the PCBM nanocrystals was approximately 96 degrees , which can be assigned to the influence of the attached side group to the fullerene ball of PCBM to bestow solubility. Atom concentration analysis showed that after thermal annealing the PCBM nanocrystals do preferentially distribute above the layer of P3HT nanocrystals inside devices.

  15. Structural properties of undoped and doped cubic GaN grown on SiC(001)

    OpenAIRE

    Martínez-Guerrero, Esteban; Bellet-Amalric, E.; Martinet, L.; Feuillet, G.; Daudin, B.

    2002-01-01

    Transmission electron microscopy and x-ray diffraction measurements reveal the presence of stacking faults ~SFs! in undoped cubic GaN thin layers. We demonstrate the importance of the defects in the interfacial region of the films by showing that the SFs act as nucleation sites for precipitates of residual impurities such as C and Si present in the GaN layers grown on SiC~001! substrates. We used the imaging secondary ion mass spectroscopy technique to locate these impurities. The systemat...

  16. GRÁINNE NÍ MHÁILLE OR « GRANUAILE », AN IRISH WOMAN , A CHIEFTAIN & A NATIONAL SYMBOL

    OpenAIRE

    O'Connell, Anne-Marie

    2010-01-01

    International audience; Gráinne Ní Mháille (aka Gráinne Mhaol, or “Granuaile”) stands out as a unique figure in Irish History and national symbolism; her fame and remarkable popularity come from the exceptional life she led, in exceptional circumstances: she was not only a chieftain, with a political and military role to play in troubled times for Ireland, under the reign of Elizabeth I of England, whom she met on a very public occasion in London, at Greenwich Castle. She was also at the head...

  17. Structural Changes of Amorphous GeTe2 Films by Annealing (Formation of Metastable Crystalline GeTe2 Films)

    Science.gov (United States)

    Fukumoto, Hirofumi; Tsunetomo, Keiji; Imura, Takeshi; Osaka, Yukio

    1987-01-01

    Amorphous GeTe2 films with the thickness ˜0.5 μm, prepared by sputtering technique, transform into the crystalline GeTe2 films with the isomorphic structure to β-cristobalite, cubic SiO2, at Ta(annealing temperature){=}200°C. The cubic phase of GeTe2 is metastable and decomposes into the mixed crystal of GeTe and Te at Ta{=}250°C.

  18. Effect of nitrogen addition on the structural, electrical, and optical properties of In-Sn-Zn oxide thin films

    Science.gov (United States)

    Jia, Junjun; Torigoshi, Yoshifumi; Suko, Ayaka; Nakamura, Shin-ichi; Kawashima, Emi; Utsuno, Futoshi; Shigesato, Yuzo

    2017-02-01

    Indium-tin-zinc oxide (ITZO) films were deposited at various nitrogen flow ratios using magnetron sputtering. At a nitrogen flow ratio of 40%, the structure of ITZO film changed from amorphous, with a short-range-ordered In2O3 phase, to a c-axis oriented InN polycrystalline phase, where InN starts to nucleate from an amorphous In2O3 matrix. Whereas, nitrogen addition had no obvious effect on the structure of indium-gallium-zinc oxide (IGZO) films even at a nitrogen flow ratio of 100%. Nitrogen addition also suppressed the formation of oxygen-related vacancies in ITZO films when the nitrogen flow ratio was less than 20%, and higher nitrogen addition led to an increase in carrier density. Moreover, a red-shift in the optical band edge was observed as the nitrogen flow ratio increased, which could be attributed to the generation of InN crystallites. We anticipate that the present findings demonstrating nitrogen-addition induced structural changes can help to understand the environment-dependent instability in amorphous IGZO or ITZO based thin-film transistors (TFTs).

  19. CRACK PROBLEM UNDER SHEAR LOADING IN CUBIC QUASICRYSTAL

    Institute of Scientific and Technical Information of China (English)

    周旺民; 范天佑; 尹姝媛

    2003-01-01

    The axisymmetric elasticity problem of cubic quasicrystal is reduced to a single higher-order partial differential equation by introducing a displacement function. Based on the work, the analytic solutions of elastic field of cubic quasicrystal with a penny-shaped crack under the shear loading are found, and the stress intensity factor and strain energy release rate are determined.

  20. Cubic Polynomials with Real or Complex Coefficients: The Full Picture

    Science.gov (United States)

    Bardell, Nicholas S.

    2016-01-01

    The cubic polynomial with real coefficients has a rich and interesting history primarily associated with the endeavours of great mathematicians like del Ferro, Tartaglia, Cardano or Vieta who sought a solution for the roots (Katz, 1998; see Chapter 12.3: The Solution of the Cubic Equation). Suffice it to say that since the times of renaissance…

  1. An application of Cubical Cohomology to Adinkras and Supersymmetry Representations

    CERN Document Server

    Doran, Charles; Landweber, Greg

    2012-01-01

    An Adinkra is a class of graphs with certain signs marking its vertices and edges, which encodes off-shell representations of the super Poincar\\'e algebra. The markings on the vertices and edges of an Adinkra are cochains for cubical cohomology. This article explores the cubical cohomology of Adinkras, treating these markings analogously to characteristic classes on smooth manifolds.

  2. Rational Cubics and Conics Representation: A Practical Approach

    Directory of Open Access Journals (Sweden)

    M. Sarfraz

    2012-08-01

    Full Text Available A rational cubic spline, with one family of shape parameters, has been discussed with the view to its application in Computer Graphics. It incorporates both conic sections and parametric cubic curves as special cases. The parameters (weights, in the description of the spline curve can be used to modify the shape of the curve, locally and globally, at the knot intervals. The rational cubic spline attains parametric   smoothness whereas the stitching of the conic segments preserves visually reasonable smoothness at the neighboring knots. The curve scheme is interpolatory and can plot parabolic, hyperbolic, elliptic, and circular splines independently as well as bits and pieces of a rational cubic spline.Key Words: Computer Graphics, Interpolation, Spline, Conic, Rational Cubic

  3. On cubic equations over $P-$adic field

    CERN Document Server

    Mukhamedov, Farrukh; Saburov, Mansoor

    2012-01-01

    We provide a solvability criteria for a depressed cubic equation in domains $\\bz_p^{*},\\bz_p,\\bq_p$. We show that, in principal, the Cardano method is not always applicable for such equations. Moreover, the numbers of solutions of the depressed cubic equation in domains $\\bz_p^{*},\\bz_p,\\bq_p$ are provided. Since $\\bbf_p\\subset\\bq_p,$ we generalize J.-P. Serre's \\cite{JPSJ} and Z.H.Sun's \\cite{ZHS1,ZHS3} results concerning with depressed cubic equations over the finite field $\\bbf_p$. Finally, all depressed cubic equations, for which the Cardano method could be applied, are described and the $p-$adic Cardano formula is provided for those cubic equations.

  4. The Body Center Cubic Quark Lattice Model

    CERN Document Server

    Lin Xu, Jiao

    2004-01-01

    The Standard Model while successful in many ways is incomplete; many questions remain. The origin of quark masses and hadronization of quarks are awaiting an answer. From the Dirac sea concept, we infer that two kinds of elementary quarks (u(0) and d(0)) constitute a body center cubic (BCC) quark lattice with a lattice constant a < $10^{-18}$m in the vacuum. Using energy band theory and the BCC quark lattice, we can deduce the rest masses and the intrinsic quantum numbers (I, S, C, b and Q) of quarks. With the quark spectrum, we deduce a baryon spectrum. The theoretical spectrum is in agreement well with the experimental results. Not only will this paper provide a physical basis for the Quark Model, but also it will open a door to study the more fundamental nature at distance scales <$10^{-18}$m. This paper predicts some new quarks $u_{c}$(6490) and d$_{b}$(9950), and new baryons $\\Lambda_{c}^{+}$(6500), $\\Lambda_{b}^{0}$(9960).

  5. Functional Ag porous films prepared by electrospinning

    Science.gov (United States)

    Dong, Guoping; Xiao, Xiudi; Liu, Xiaofeng; Qian, Bin; Liao, Yang; Wang, Chen; Chen, Danping; Qiu, Jianrong

    2009-06-01

    Face-centered cubic Ag porous films have been prepared directly from the heat treatment of AgNO 3-doped poly(vinyl alcohol) (PVA) electrospun nanofibers. Using Rhodamine B (RB) as the probing molecule, the surface-enhanced Raman scattering (SERS) effect of Ag porous films was demonstrated. The antibacterial activity of Ag porous films was also studied in this work. The propagation and biological activity of yeast cells were effectively inhibited by Ag porous films. These functional Ag porous films were expected to be applied in many fields, such as catalysis, diagnostics, sensors and antibacterial, etc.

  6. Oxidation of Membrane Curvature-Regulating Phosphatidylethanolamine Lipid Results in Formation of Bilayer and Cubic Structures.

    Science.gov (United States)

    Sankhagowit, Shalene; Lee, Ernest Y; Wong, Gerard C L; Malmstadt, Noah

    2016-03-15

    Oxidation is associated with conditions related to chronic inflammations and aging. Cubic structures have been observed in the smooth endoplasmic reticulum and mitochondrial membranes of cells under oxidative stress (e.g., tumor cells and virus-infected cells). It has been previously suspected that oxidation can result in the rearrangement of lipids from a fluid lamellar phase to a cubic structure in organelles containing membranes enriched with amphiphiles that have nonzero intrinsic curvature, such as phosphatidylethanolamine (PE) and cardiolipin. This study focuses on the oxidation of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE), a lipid that natively forms an inverted hexagonal phase at physiological conditions. The oxidized samples contain an approximately 3:2 molar ratio of nonoxidized to oxidized DOPE. Optical microscopy images collected during the hydration of this mixture from a dried film suggest that the system evolves into a coexistence of a stable fluid lamellar phase and transient square lattice structures with unit cell sizes of 500-600 nm. Small-angle X-ray scattering of the same lipid mixture yielded a body-centered Im3m cubic phase with the lattice parameter of 14.04 nm. On average, the effective packing parameter of the oxidized DOPE species was estimated to be 0.657 ± 0.069 (standard deviation). This suggests that the oxidation of PE leads to a group of species with inverted molecular intrinsic curvature. Oxidation can create amphiphilic subpopulations that potently impact the integrity of the membrane, since negative Gaussian curvature intrinsic to cubic phases can enable membrane destabilization processes.

  7. Determination of the surface band bending in InxGa1−xN films by hard x-ray photoemission spectroscopy

    Directory of Open Access Journals (Sweden)

    Mickael Lozac'h, Shigenori Ueda, Shitao Liu, Hideki Yoshikawa, Sang Liwen, Xinqiang Wang, Bo Shen, Kazuaki Sakoda, Keisuke Kobayashi and Masatomo Sumiya

    2013-01-01

    Full Text Available Core-level and valence band spectra of InxGa1−xN films were measured using hard x-ray photoemission spectroscopy (HX-PES. Fine structure, caused by the coupling of the localized Ga 3d and In 4d with N 2s states, was experimentally observed in the films. Because of the large detection depth of HX-PES (~20 nm, the spectra contain both surface and bulk information due to the surface band bending. The InxGa1−xN films (x = 0–0.21 exhibited upward surface band bending, and the valence band maximum was shifted to lower binding energy when the mole fraction of InN was increased. On the other hand, downward surface band bending was confirmed for an InN film with low carrier density despite its n-type conduction. Although the Fermi level (EF near the surface of the InN film was detected inside the conduction band as reported previously, it can be concluded that EF in the bulk of the film must be located in the band gap below the conduction band minimum.

  8. The Role of Ligand Packing Frustration in Body-Centered Cubic (bcc) Superlattices of Colloidal Nanocrystals.

    Science.gov (United States)

    Goodfellow, Brian W; Yu, Yixuan; Bosoy, Christian A; Smilgies, Detlef-M; Korgel, Brian A

    2015-07-02

    This paper addresses the assembly of body centered-cubic (bcc) superlattices of organic ligand-coated nanocrystals. First, examples of bcc superlattices of dodecanethiol-capped Au nanocrystals and oleic acid-capped PbS and PbSe nanocrystals are presented and examined by transmission electron microscopy (TEM) and grazing incidence small-angle X-ray scattering (GISAXS). These superlattices tend to orient on their densest (110) superlattice planes and exhibit a significant amount of {112} twinning. The same nanocrystals deposit as monolayers with hexagonal packing, and these thin films can coexist with thicker bcc superlattice layers, even though there is no hexagonal plane in a bcc lattice. Both the preference of bcc in bulk films over the denser face-centered cubic (fcc) superlattice structure and the transition to hexagonal monolayers can be rationalized in terms of packing frustration of the ligands. A model is presented to calculate the difference in entropy associated with capping ligand packing frustration in bcc and fcc superlattices.

  9. The daytime boundary layer in the Inn Valley - A model evaluation study with high-quality turbulence measurements

    Science.gov (United States)

    Goger, Brigitta; Rotach, Mathias W.; Gohm, Alexander; Fuhrer, Oliver; Stiperski, Ivana

    2016-04-01

    Atmospheric processes associated with complex terrain include various phenomena on the meso- and microscale, which contribute significantly to the local weather in mountainous areas of the Earth. One of the most prominent and well-known boundary-layer phenomena in mountainous terrain is the daytime valley wind circulation, which is very pronounced on clear-sky days with weak synoptic forcing. We use several chosen "valley wind days" in the Inn Valley, Austria, as case studies for the evaluation of the performance of the NWP model COSMO on a horizontal resolution of 1.1 km with a focus on boundary-layer processes and turbulent exchange. The overall goal is to evaluate the model setup and to investigate whether the model's physics schemes (initially developed for horizontally homogeneous and flat surroundings) are suitable for truly complex terrain. We evaluate the model by using measurements from the so-called "i-Box" located in the Inn Valley. The i-Box consists of six core sites that are located at representative locations in the Inn Valley, and two remote sensing systems (wind Lidar and HATPRO passive T/RH profiler) in the city of Innsbruck. The long-term data set provides a data pool of high-resolution velocity variances, turbulence variables, radiation, soil moisture, and vertical profiles of temperature, humidity, and wind in the lower troposphere, which allows a process-oriented analysis. A special focus is laid on the daytime valley boundary layer and its interaction with the developing up-valley wind. Vertical cross-sections show that the valley wind has an asymmetric structure, hence, the i-Box stations show a high spatial variability. While the station on the valley bottom and on the south-facing slope are clearly under the strong influence of the valley wind, the two stations on the north-facing slope are rather dominated by slope flows. We find that the valley wind has a strong (indirect) influence on the development of the local turbulence kinetic

  10. Oriented growth of thin films of samarium oxide by MOCVD

    Indian Academy of Sciences (India)

    K Shalini; S A Shivashankar

    2005-02-01

    Thin films of Sm2O3 have been grown on Si(100) and fused quartz by low-pressure chemical vapour deposition using an adducted -diketonate precursor. The films on quartz are cubic, with no preferred orientation at lower growth temperatures (∼ 550°C), while they grow with a strong (111) orientation as the temperature is raised (to 625°C). On Si(100), highly oriented films of cubic Sm2O3 at 625°C, and a mixture of monoclinic and cubic polymorphs of Sm2O3 at higher temperatures, are formed. Films grown on either substrate are very smooth and fine-grained. Infrared spectroscopic study reveals that films grown above 600°C are free of carbon.

  11. Influence of In-N Clusters on Band Gap Energy of Dilute Nitride In x Ga1-x N y As1-y

    Science.gov (United States)

    Zhao, Chuan-Zhen; Guo, Heng-Fei; Chen, Li-Ying; Tang, Chun-Xiao; Lu, Ke-Qing

    2016-05-01

    The In-N clusters form in the dilute nitride InxGa1-xNyAs1-y alloys after annealing. It is found that the formation of the In-N clusters not only raises the N levels lying above the conduction band minimum (CBM) of InGaAs, but also raises the N levels below the CBM of InGaAs, leading to the variation of the impurity-host interaction. The blueshift of the band gap energy is relative to the variation of the impurity-host interaction. In order to describe the blueshift of the band gap energy due to the formation of the In-N clusters, a model is developed. It is found that the model can describe the blueshift of the band gap energy well. In addition, it is found the blueshift of the band gap energy due to the atom interdiffusion at the interface can be larger than that due to the formation of the In-N clusters. Supported by the National Natural Science Foundation of China under Grant No. 61504094, Tinjin Research Program of Application Foundation and Advanced Technology under No. 15JCYBJC16300, and Tianjin City High School Science and Technology Fund Planning Project No. 20120609

  12. Cubic B-spline curve approximation by curve unclamping

    OpenAIRE

    Chen, Xiao-Diao; Ma, Weiyin; Paul, Jean-Claude

    2010-01-01

    International audience; A new approach for cubic B-spline curve approximation is presented. The method produces an approximation cubic B-spline curve tangent to a given curve at a set of selected positions, called tangent points, in a piecewise manner starting from a seed segment. A heuristic method is provided to select the tangent points. The first segment of the approximation cubic B-spline curve can be obtained using an inner point interpolation method, least-squares method or geometric H...

  13. On q-power cycles in cubic graphs

    DEFF Research Database (Denmark)

    Bensmail, Julien

    2017-01-01

    In the context of a conjecture of Erdos and Gyárfás, we consider, for any q ≥ 2, the existence of q-power cycles (i.e. with length a power of q) in cubic graphs. We exhibit constructions showing that, for every q ≥ 3, there exist arbitrarily large cubic graphs with no q-power cycles. Concerning...... the remaining case q = 2 (which corresponds to the conjecture of Erdos and Gyárfás), we show that there exist arbitrarily large cubic graphs whose only 2-power cycles have length 4 only, or 8 only....

  14. On q-power cycles in cubic graphs

    DEFF Research Database (Denmark)

    Bensmail, Julien

    2016-01-01

    In the context of a conjecture of Erdos and Gyárfás, we consider, for any q ≥ 2, the existence of q-power cycles (i.e. with length a power of q) in cubic graphs. We exhibit constructions showing that, for every q ≥ 3, there exist arbitrarily large cubic graphs with no q-power cycles. Concerning...... the remaining case q = 2 (which corresponds to the conjecture of Erdos and Gyárfás), we show that there exist arbitrarily large cubic graphs whose only 2-power cycles have length 4 only, or 8 only....

  15. Electronic and thermoelectric properties of InN studied using ab initio density functional theory and Boltzmann transport calculations

    Energy Technology Data Exchange (ETDEWEB)

    Borges, P. D., E-mail: pdborges@gmail.com, E-mail: lscolfaro@txstate.edu; Scolfaro, L., E-mail: pdborges@gmail.com, E-mail: lscolfaro@txstate.edu [Department of Physics, Texas State University, San Marcos, Texas 78666 (United States)

    2014-12-14

    The thermoelectric properties of indium nitride in the most stable wurtzite phase (w-InN) as a function of electron and hole concentrations and temperature were studied by solving the semiclassical Boltzmann transport equations in conjunction with ab initio electronic structure calculations, within Density Functional Theory. Based on maximally localized Wannier function basis set and the ab initio band energies, results for the Seebeck coefficient are presented and compared with available experimental data for n-type as well as p-type systems. Also, theoretical results for electric conductivity and power factor are presented. Most cases showed good agreement between the calculated properties and experimental data for w-InN unintentionally and p-type doped with magnesium. Our predictions for temperature and concentration dependences of electrical conductivity and power factor revealed a promising use of InN for intermediate and high temperature thermoelectric applications. The rigid band approach and constant scattering time approximation were utilized in the calculations.

  16. Structural and electronic properties of InN nanowire network grown by vapor-liquid-solid method

    Energy Technology Data Exchange (ETDEWEB)

    Barick, B. K., E-mail: bkbarick@gmail.com, E-mail: subho-dh@yahoo.co.in; Dhar, S., E-mail: bkbarick@gmail.com, E-mail: subho-dh@yahoo.co.in [Department of Physics, Indian Institute of Technology, Bombay, Mumbai-400076 (India); Rodríguez-Fernández, Carlos; Cantarero, Andres [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain)

    2015-05-15

    Growth of InN nanowires have been carried out on quartz substrates at different temperatures by vapor-liquid-solid (VLS) technique using different thicknesses of Au catalyst layer. It has been found that a narrow window of Au layer thickness and growth temperature leads to multi-nucleation, in which each site acts as the origin of several nanowires. In this multi-nucleation regime, several tens of micrometer long wires with diameter as small as 20 nm are found to grow along [112{sup -}0] direction (a-plane) to form a dense network. Structural and electronic properties of these wires are studied. As grown nanowires show degenerate n-type behavior. Furthermore, x-ray photoemission study reveals an accumulation of electrons on the surface of these nanowires. Interestingly, the wire network shows persistence of photoconductivity for several hours after switching off the photoexcitation.

  17. Individual electron and hole localization in submonolayer InN quantum sheets embedded in GaN

    Energy Technology Data Exchange (ETDEWEB)

    Feix, F., E-mail: feix@pdi-berlin.de; Flissikowski, T.; Chèze, C.; Calarco, R.; Grahn, H. T.; Brandt, O. [Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e. V., Hausvogteiplatz 5–7, 10117 Berlin (Germany)

    2016-07-25

    We investigate sub-monolayer InN quantum sheets embedded in GaN(0001) by temperature-dependent photoluminescence spectroscopy under both continuous-wave and pulsed excitation. Both the peak energy and the linewidth of the emission band associated with the quantum sheets exhibit an anomalous dependence on temperature indicative of carrier localization. Photoluminescence transients reveal a power law decay at low temperatures reflecting that the recombining electrons and holes occupy spatially separate, individual potential minima reminiscent of conventional (In,Ga)N(0001) quantum wells exhibiting the characteristic disorder of a random alloy. At elevated temperatures, carrier delocalization sets in and is accompanied by a thermally activated quenching of the emission. We ascribe the strong nonradiative recombination to extended states in the GaN barriers and confirm our assumption by a simple rate-equation model.

  18. The compressibility of cubic white and orthorhombic, rhombohedral, and simple cubic black phosphorus

    Energy Technology Data Exchange (ETDEWEB)

    Clark, Simon M; Zaug, Joseph

    2010-03-10

    The effect of pressure on the crystal structure of white phosphorus has been studied up to 22.4 GPa. The ?alpha phase was found to transform into the alpha' phase at 0.87 +- 0.04 GPa with a volume change of 0.1 +- 0.3 cc/mol. A fit of a second order Birch- Murnaghan equation to the data gave Vo = 16.94 ? 0.08 cc/mol and Ko = 6.7 +- 0.5 GPa for the alpha phase and Vo = 16.4 +- 0.1 cc/mol and Ko = 9.1 +- 0.3 GPa for the alpha' phase. The alpha' phase was found to transform to the A17 phase of black phosphorus at 2.68 +- 0.34 GPa and then with increasing pressure to the A7 and then simple cubic phase of black phosphorus. A fit of a second order Birch-Murnaghan equation to our data combined with previous measurements gave Vo = 11.43 +- 0.05 cc/mol and Ko = 34.7 +- 0.5 GPa for the A17 phase, Vo = 9.62 +- 0.01 cc/mol and Ko = 65.0 +- 0.6 GPa for the A7 phase and , Vo = 9.23 +- 0.01 cc/mol and Ko = 72.5 +- 0.3 GPa for the simple cubic phase.

  19. Growth kinetics and structural perfection of (InN)1/(GaN)1-20 short-period superlattices on +c-GaN template in dynamic atomic layer epitaxy

    Science.gov (United States)

    Kusakabe, Kazuhide; Hashimoto, Naoki; Itoi, Takaomi; Wang, Ke; Imai, Daichi; Yoshikawa, Akihiko

    2016-04-01

    The growth kinetics and structural perfection of (InN)1/(GaN)1-20 short-period superlattices (SPSs) were investigated with their application to ordered alloys in mind. The SPSs were grown on +c-GaN template at 650 °C by dynamic atomic layer epitaxy in conventional plasma-assisted molecular beam epitaxy. It was found that coherent structured InN/GaN SPSs could be fabricated when the thickness of the GaN barrier was 4 ML or above. Below 3 ML, the formation of SPSs was quite difficult owing to the increased strain in the SPS structure caused by the use of GaN as a template. The effective or average In composition of the (InN)1/(GaN)4 SPSs was around 10%, and the corresponding InN coverage in the ˜1 ML-thick InN wells was 50%. It was found that the effective InN coverage in ˜1 ML-thick InN wells could be varied with the growth conditions. In fact, the effective In composition could be increased up to 13.5%, i.e., the corresponding effective InN coverage was about 68%, by improving the capping/freezing speed by increasing the growth rate of the GaN barrier layer.

  20. Global infinite energy solutions for the cubic wave equation

    OpenAIRE

    Burq, N.; L. Thomann; Tzvetkov, N.

    2012-01-01

    International audience; We prove the existence of infinite energy global solutions of the cubic wave equation in dimension greater than 3. The data is a typical element on the support of suitable probability measures.

  1. The Coulombic Lattice Potential of Ionic Compounds: The Cubic Perovskites.

    Science.gov (United States)

    Francisco, E.; And Others

    1988-01-01

    Presents coulombic models representing the particles of a system by point charges interacting through Coulomb's law to explain coulombic lattice potential. Uses rubidium manganese trifluoride as an example of cubic perovskite structure. Discusses the effects on cluster properties. (CW)

  2. Spinning solitons in cubic-quintic nonlinear media

    Indian Academy of Sciences (India)

    Lucian-Cornel Crasovan; Boris A Malomed; Dumitru Mihalache

    2001-11-01

    We review recent theoretical results concerning the existence, stability and unique features of families of bright vortex solitons (doughnuts, or ‘spinning’ solitons) in both conservative and dissipative cubic-quintic nonlinear media.

  3. Stress Intensity of Antiplane Conjugate Cracks in Cubic Quasicrystal

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei

    2008-01-01

    Based on the theory of Muskhelishvili, the general solutions for stress and strain of conjugate cracks in cubic quasicrystal are obtained, with which the stress intensity factors of cubic quasicrystal at crack tips and the stress distribution functions of phonon and phason fields are given. The results show that though phason field is coupled with phonon field by constitutive equations, the stress intensity factors are not coupled with any other factors.

  4. Synthesis, characterization and processing of cubic iron pyrite nanocrystals in a photovoltaic cell

    Energy Technology Data Exchange (ETDEWEB)

    Alam Khan, M., E-mail: alamkhan77@gmail.com; Sarker, J.C.; Lee, Seunyong; Mangham, Scott C.; Manasreh, M.O.

    2014-12-15

    Cubic iron pyrite (fool's gold) nanocrystals with an average diameter of ∼60 nm were grown in an oleylamine ligand which acts as a solvent and surfactant without the utilization of alkyl phosphine and phosphonic acids at 230 °C in a Schlenk flask. For the first time photoluminescence properties of such cubic nanocrystals were analyzed at 77 K, showing band gaps of 1.71 eV. However, UV–Vis spectra shows a band gap of 1.41 eV for the same nanocrystals, close to the direct band gap (1.38 eV) of reported pyrite materials. The discrepancy of 0.3 eV in absorption (UV–Vis) and emission spectra (PL) are attributed to the phonon coupling (stokes shift). The prepared cubic nanocrystals were well suited for an inexpensive thin film solar cells and further processed and spin casted with a synthesized CdSe quantum dots in chloroform solvent as a bulk-heterojunction (BHJ) solar cell in order to get photovoltaic responses in real devices. We successfully report here an efficiency of 0.5% with the J{sub SC} of 3.7 mA/cm{sup −2} and V{sub OC} of 0.16 mV with a cell structure of ITO/PEDOT:PSS/FeS{sub 2}:CdSe/Au. The morphology and optoelectronic properties are elucidated by SEM, TEM, TEM-EDS, XRD, micro-Raman spectra, IV curve and micro-PL techniques. - Highlights: • Excellent cubic iron pyrite nanocrystals are synthesized by using an oleylamine ligand. • First time PL spectra were used to measure band gaps of such colloidal cubic nanocrytsals. • Pyrite ink was made in suitable solvent to fabricate practical devices. • A successful 0.5% efficiency is reported in bulk-heterojunction cell with CdSe QDs.

  5. Spinor bose gases in cubic optical lattice

    Energy Technology Data Exchange (ETDEWEB)

    Mobarak, Mohamed Saidan Sayed Mohamed

    2014-01-27

    In recent years the quantum simulation of condensed-matter physics problems has resulted from exciting experimental progress in the realm of ultracold atoms and molecules in optical lattices. In this thesis we analyze theoretically a spinor Bose gas loaded into a three-dimensional cubic optical lattice. In order to account for different superfluid phases of spin-1 bosons with a linear Zeeman effect, we work out a Ginzburg-Landau theory for the underlying spin-1 Bose-Hubbard model. To this end we add artificial symmetry-breaking currents to the spin-1 Bose-Hubbard Hamiltonian in order to break the global U (1) symmetry. With this we determine a diagrammatic expansion of the grand-canonical free energy up to fourth order in the symmetry-breaking currents and up to the leading non-trivial order in the hopping strength which is of first order. As a cross-check we demonstrate that the resulting grand-canonical free energy allows to recover the mean-field theory. Applying a Legendre transformation to the grand-canonical free energy, where the symmetry-breaking currents are transformed to order parameters, we obtain the effective Ginzburg-Landau action. With this we calculate in detail at zero temperature the Mott insulator-superfluid quantum phase boundary as well as condensate and particle number density in the superfluid phase. We find that both mean-field and Ginzburg-Landau theory yield the same quantum phase transition between the Mott insulator and superfluid phases, but the range of validity of the mean-field theory turns out to be smaller than that of the Ginzburg-Landau theory. Due to this finding we expect that the Ginzburg-Landau theory gives better results for the superfluid phase and, thus, we restrict ourselves to extremize only the effective Ginzburg-Landau action with respect to the order parameters. Without external magnetic field the superfluid phase is a polar (ferromagnetic) state for anti-ferromagnetic (ferromagnetic) interactions, i.e. only the

  6. Superconducting Electronic Film Structures

    Science.gov (United States)

    1991-02-14

    cubic, yttria stabilized, zirconia (YSZ) single crystals with (100) orientation and ao = 0.512 to 0.516 nm. Films were magnetron-sputtered... Crown by Solid-State and Vapor-Phase Epitaxy," IEEE Trans. Uagn. 25(2), 2538 (1989). 6. J. H. Kang, R. T. Kampwirth, and K. E. Gray, "Superconductivity...summarized in Fig. 1, are too high for SrTiO3 or yttria- stabilized zirconia (YSZ) to be used in rf applications. MgO, LaAIO 3 , and LaGaO3 have a tan 6

  7. A new hypercube variant: Fractal Cubic Network Graph

    Directory of Open Access Journals (Sweden)

    Ali Karci

    2015-03-01

    Full Text Available Hypercube is a popular and more attractive interconnection networks. The attractive properties of hypercube caused the derivation of more variants of hypercube. In this paper, we have proposed two variants of hypercube which was called as “Fractal Cubic Network Graphs”, and we have investigated the Hamiltonian-like properties of Fractal Cubic Network Graphs FCNGr(n. Firstly, Fractal Cubic Network Graphs FCNGr(n are defined by a fractal structure. Further, we show the construction and characteristics analyses of FCNGr(n where r=1 or r=2. Therefore, FCNGr(n is a Hamiltonian graph which is obtained by using Gray Code for r=2 and FCNG1(n is not a Hamiltonian Graph. Furthermore, we have obtained a recursive algorithm which is used to label the nodes of FCNG2(n. Finally, we get routing algorithms on FCNG2(n by utilizing routing algorithms on the hypercubes.

  8. Ferromagnetic Ground States in Face-Centered Cubic Hubbard Clusters

    Science.gov (United States)

    Souza, T. X. R.; Macedo, C. A.

    2016-01-01

    In this study, the ground state energies of face-centered cubic Hubbard clusters are analyzed using the Lanczos method. Examination of the ground state energy as a function of the number of particle per site n showed an energy minimum for face-centered cubic structures. This energy minimum decreased in n with increasing coulombic interaction parameter U. We found that the ground state energy had a minimum at n = 0.6, when U = 3W, where W denotes the non-interacting energy bandwidth and the face-centered cubic structure was ferromagnetic. These results, when compared with the properties of nickel, shows strong similarity with other finite temperature analyses in the literature and supports the Hirsh’s conjecture that the interatomic direct exchange interaction dominates in driving the system into a ferromagnetic phase. PMID:27583653

  9. Superconductivity in cubic noncentrosymmetric PdBiSe Crystal

    Science.gov (United States)

    Joshi, B.; Thamizhavel, A.; Ramakrishnan, S.

    2015-03-01

    Mixing of spin singlet and spin triplet superconducting pairing state is expected in noncentrosymmetric superconductors (NCS) due to the inherent presence of Rashba-type antisymmetric spin-orbit coupling. Unlike low symmetry (tetragonal or monoclinic) NCS, parity is isotropicaly broken in space for cubic NCS and can additionally lead to the coexistence of magnetic and superconducting state under certain conditions. Motivated with such enriched possibility of unconventional superconducting phases in cubic NCS we are reporting successful formation of single crystalline cubic noncentrosymmetric PdBiSe with lattice parameter a = 6.4316 Å and space group P21 3 (space group no. 198) which undergoes to superconducting transition state below 1.8 K as measured by electrical transport and AC susceptibility measurements. Significant strength of Rashba-type antisymmetric spin-orbit coupling can be expected for PdBiSe due to the presence of high Z (atomic number) elements consequently making it potential candidate for unconventional superconductivity.

  10. Cubic interactions of Maxwell-like higher spins

    CERN Document Server

    Francia, Dario; Mkrtchyan, Karapet

    2016-01-01

    We study the cubic vertices for Maxwell-like higher-spins in flat space. Reducibility of their free spectra implies that a single cubic vertex involving any three fields subsumes a number of couplings among different particles of various spins. The resulting vertices do not involve traces of the fields and in this sense are simpler than their Fronsdal counterparts. We propose an extension of both the free theory and of its cubic deformation to a more general class of partially reducible systems, that one can obtain from the original theory upon imposing trace constraints of various orders. The key to our results is a version of the Noether procedure allowing to systematically account for the deformations of the transversality conditions to be imposed on the gauge parameters at the free level.

  11. Extended temperature dependence of elastic constants in cubic crystals.

    Science.gov (United States)

    Telichko, A V; Sorokin, B P

    2015-08-01

    To extend the theory of the temperature dependence of the elastic constants in cubic crystals beyond the second- and third-order elastic constants, the fourth-order elastic constants, as well as the non-linearity in the thermal expansion temperature dependence, have been taken into account. Theoretical results were represented as temperature functions of the effective elastic constants and compared with experimental data for a number of cubic crystals, such as alkali metal halides, and elements gold and silver. The relations obtained give a more accurate description of the experimental temperature dependences of second-order elastic constants for a number of cubic crystals, including deviations from linear behavior. A good agreement between theoretical estimates and experimental data has been observed.

  12. Tetragonal and cubic zirconia multilayered ceramic constructs created by EPD.

    Science.gov (United States)

    Mochales, Carolina; Frank, Stefan; Zehbe, Rolf; Traykova, Tania; Fleckenstein, Christine; Maerten, Anke; Fleck, Claudia; Mueller, Wolf-Dieter

    2013-02-14

    The interest in electrophoretic deposition (EPD) for nanomaterials and ceramics production has widely increased due to the versatility of this technique to effectively combine different materials in unique shapes and structures. We successfully established an EPD layering process with submicrometer sized powders of Y-TZP with different mol percentages of yttrium oxide (3 and 8%) and produced multilayers of alternating tetragonal and cubic phases with a clearly defined interface. The rationale behind the design of these multilayer constructs was to optimize the properties of the final ceramic by combining the high mechanical toughness of the tetragonal phase of zirconia together with the high ionic conductivity of its cubic phase. In this work, a preliminary study of the mechanical properties of these constructs proved the good mechanical integrity of the multilayered constructs obtained as well as crack deflection in the interface between tetragonal and cubic zirconia layers.

  13. Hardness and thermal stability of cubic silicon nitride

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Kragh, Flemming; Frost, D. J.

    2001-01-01

    The hardness and thermal stability of cubic spinel silicon nitride (c-Si3N4), synthesized under high-pressure and high-temperature conditions, have been studied by microindentation measurements, and x-ray powder diffraction and scanning electron microscopy, respectively The phase at ambient...... temperature has an average hardness of 35.31 GPa, slightly larger than SiO2 stishovite, which is often referred to as the third hardest material after diamond and cubic boron nitride. The cubic phase is stable up to 1673 K in air. At 1873 K, alpha -and beta -Si3N4 phases are observed, indicating a phase...... transformation sequence of c-to-alpha -to-beta -Si3N4 phases....

  14. Image interpolation by two-dimensional parametric cubic convolution.

    Science.gov (United States)

    Shi, Jiazheng; Reichenbach, Stephen E

    2006-07-01

    Cubic convolution is a popular method for image interpolation. Traditionally, the piecewise-cubic kernel has been derived in one dimension with one parameter and applied to two-dimensional (2-D) images in a separable fashion. However, images typically are statistically nonseparable, which motivates this investigation of nonseparable cubic convolution. This paper derives two new nonseparable, 2-D cubic-convolution kernels. The first kernel, with three parameters (designated 2D-3PCC), is the most general 2-D, piecewise-cubic interpolator defined on [-2, 2] x [-2, 2] with constraints for biaxial symmetry, diagonal (or 90 degrees rotational) symmetry, continuity, and smoothness. The second kernel, with five parameters (designated 2D-5PCC), relaxes the constraint of diagonal symmetry, based on the observation that many images have rotationally asymmetric statistical properties. This paper also develops a closed-form solution for determining the optimal parameter values for parametric cubic-convolution kernels with respect to ensembles of scenes characterized by autocorrelation (or power spectrum). This solution establishes a practical foundation for adaptive interpolation based on local autocorrelation estimates. Quantitative fidelity analyses and visual experiments indicate that these new methods can outperform several popular interpolation methods. An analysis of the error budgets for reconstruction error associated with blurring and aliasing illustrates that the methods improve interpolation fidelity for images with aliased components. For images with little or no aliasing, the methods yield results similar to other popular methods. Both 2D-3PCC and 2D-5PCC are low-order polynomials with small spatial support and so are easy to implement and efficient to apply.

  15. SpaceInn hare-and-hounds exercise: Estimation of stellar properties using space-based asteroseismic data

    CERN Document Server

    Reese, D R; Davies, G R; Miglio, A; Antia, H M; Ball, W H; Basu, S; Buldgen, G; Christensen-Dalsgaard, J; Coelho, H R; Hekker, S; Houdek, G; Lebreton, Y; Mazumdar, A; Metcalfe, T S; Aguirre, V Silva; Stello, D; Verma, K

    2016-01-01

    Context: Detailed oscillation spectra comprising individual frequencies for numerous solar-type stars and red giants are or will become available. These data can lead to a precise characterisation of stars. Aims: Our goal is to test and compare different methods for obtaining stellar properties from oscillation frequencies and spectroscopic constraints, in order to evaluate their accuracy and the reliability of the error bars. Methods: In the context of the SpaceInn network, we carried out a hare-and-hounds exercise in which one group produced "observed" oscillation spectra for 10 artificial solar-type stars, and various groups characterised these stars using either forward modelling or acoustic glitch signatures. Results: Results based on the forward modelling approach were accurate to 1.5 % (radius), 3.9 % (mass), 23 % (age), 1.5 % (surface gravity), and 1.8 % (mean density). For the two 1 Msun stellar targets, the accuracy on the age is better than 10 % thereby satisfying PLATO 2.0 requirements. The averag...

  16. Ultrahigh polarimetric image contrast enhancement for skin cancer diagnosis using InN plasmonic nanoparticles in the terahertz range.

    Science.gov (United States)

    Ney, Michael; Abdulhalim, Ibrahim

    2015-01-01

    Mueller matrix imaging sensitivity, to delicate water content changes in tissue associated with early stages of skin cancer, is demonstrated by numerical modeling to be enhanced by localized surface plasmon resonance (LSPR) effects at the terahertz (THz) range when InN nanoparticles (NPs) coated with Parylene-C are introduced into the skin. A skin tissue model tailored for THz wavelengths is established for a Monte Carlo simulation of polarized light propagation and scattering, and a comparative study based on simulated Mueller matrices is presented considering different NPs’ parameters and insertion into the skin methods. The insertion of NPs presenting LSPR in the THz is demonstrated to enable the application of polarization-based sample characterization techniques adopted from the scattering dominated visible wavelengths domain for the, otherwise, relatively low scattering THz domain, where such approach is irrelevant without the NPs. Through these Mueller polarimetry techniques, the detection of water content variations in the tissue is made possible and with high sensitivity. This study yields a limit of detection down to 0.0018% for relative changes in the water content based on linear degree of polarization--an improvement of an order of magnitude relative to the limit of detection without NPs calculated in a previous ellipsometric study.

  17. Impact of film thickness on the morphology of mesoporous carbon films using organic-organic self-assembly.

    Science.gov (United States)

    Vogt, Bryan D; Chavez, Vicki L; Dai, Mingzhi; Arreola, M Regina Croda; Song, Lingyan; Feng, Dan; Zhao, Dongyuan; Perera, Ginusha M; Stein, Gila E

    2011-05-03

    Mesoporous polymer and carbon thin films are prepared by the organic-organic self-assembly of an oligomeric phenolic resin with an amphiphilic triblock copolymer template, Pluronic F127. The ratio of resin to template is selected such that a body-centered cubic (Im3m) mesostructure is formed in the bulk. However, well-ordered mesoporous films are not always obtained for thin films (body-centered cubic symmetry with a preferential orientation of the closest-packed (110) plane parallel to the substrate. Film thickness and initial composition of the carbonizable precursors in the template are critical factors in determining the morphology of mesoporous carbon films. These results provide insight into why difficulties have been reported in producing ultrathin ordered mesoporous carbon films using cooperative organic-organic self-assembly.

  18. Higher-spin Interactions from CFT: The Complete Cubic Couplings

    CERN Document Server

    Sleight, Charlotte

    2016-01-01

    In this letter we provide a complete holographic reconstruction of the cubic couplings in the minimal bosonic higher-spin theory in AdS$_{d+1}$. For this purpose we also determine the OPE coefficients of all single-trace conserved currents in the $d$-dimensional free scalar $O\\left(N\\right)$ vector model, and compute the tree-level three-point Witten diagram amplitudes for a generic cubic interaction of higher-spin gauge fields in the metric-like formulation.

  19. Classifying Cubic Edge-Transitive Graphs of Order 8

    Indian Academy of Sciences (India)

    Mehdi Alaeiyan; M K Hosseinipoor

    2009-11-01

    A simple undirected graph is said to be semisymmetric if it is regular and edge-transitive but not vertex-transitive. Let be a prime. It was shown by Folkman (J. Combin. Theory 3(1967) 215--232) that a regular edge-transitive graph of order 2 or 22 is necessarily vertex-transitive. In this paper, an extension of his result in the case of cubic graphs is given. It is proved that, every cubic edge-transitive graph of order 8 is symmetric, and then all such graphs are classified.

  20. Possible form of multi-polar interaction in cubic lattice

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, Osamu; Shiina, Ryousuke; Shiba, Hiroyuki

    2003-05-01

    The invariant form of interaction between multi-poles, including the octupole, is studied for the simple cubic (SC), body centered and face centered cubic lattices. The coupling terms can be arranged in a way similar to that of the hopping matrix between the LCAO's. A table for SC by Shiina et al. (J. Phys. Soc. Japan 66 (1997) 1741) is generalized for the general wave number case of the three types of lattice. Recent experimental result of TmTe is thereby analyzed. The development of the ferromagnetic moment below the anti-ferromagnetic transition under the anti-ferro quadrupolar order phase is discussed in this connection.

  1. Possible form of multi-polar interaction in cubic lattice

    Science.gov (United States)

    Sakai, Osamu; Shiina, Ryousuke; Shiba, Hiroyuki

    2003-05-01

    The invariant form of interaction between multi-poles, including the octupole, is studied for the simple cubic (SC), body centered and face centered cubic lattices. The coupling terms can be arranged in a way similar to that of the hopping matrix between the LCAO's. A table for SC by Shiina et al. (J. Phys. Soc. Japan 66 (1997) 1741) is generalized for the general wave number case of the three types of lattice. Recent experimental result of TmTe is thereby analyzed. The development of the ferromagnetic moment below the anti-ferromagnetic transition under the anti-ferro quadrupolar order phase is discussed in this connection.

  2. Counting perfect matchings of cubic graphs in the geometric dual

    CERN Document Server

    Jiménez, Andrea

    2010-01-01

    Lov\\'asz and Plummer conjectured, in the mid 1970's, that every cubic graph G with no cutedge has an exponential in |V(G)| number of perfect matchings. In this work we show that every cubic planar graph G whose geometric dual graph is a stack triangulation has at least 3 times the golden ratio to |V(G)|/72 distinct perfect matchings. Our work builds on a novel approach relating Lov\\'asz and Plummer's conjecture and the number of so called groundstates of the widely studied Ising model from statistical physics.

  3. Elastic interaction of point defects in crystals with cubic symmetry

    Science.gov (United States)

    Kuz'michev, S. V.; Kukushkin, S. A.; Osipov, A. V.

    2013-07-01

    The energy of elastic mechanical interaction between point defects in cubic crystals is analyzed numerically. The finite-element complex ANSYS is used to investigate the character of interaction between point defects depending on their location along the crystallographic directions , , and on the distance from the free boundary of the crystal. The numerical results are compared with the results of analytic computations of the energy of interaction between two point defects in an infinite anisotropic medium with cubic symmetry. The interaction between compressible and incompressible defects of general type is studied. Conditions for onset of elastic attraction between the defects, which leads to general relaxation of the crystal elastic energy, are obtained.

  4. Cubic surfaces and their invariants: Some memories of Raymond Stora

    Directory of Open Access Journals (Sweden)

    Michel Bauer

    2016-11-01

    I then turn to the study of the family of cubic surfaces. They depend on 20 parameters, and the action of the 15 parameter group SL4(C splits the family in orbits depending on 5 parameters. This takes us into the realm of (geometric invariant theory. I review briefly the classical theorems on the structure of the ring of polynomial invariants and illustrate its many facets by looking at a simple example, before turning to the already involved case of cubic surfaces. The invariant ring was described in the 19th century. I show how to retrieve this description via counting/generating functions and character formulae.

  5. Magnetic Properties of Heisenberg Thin Films in an External Field

    Institute of Scientific and Technical Information of China (English)

    CHEN Hong; ZHANG Jing

    2004-01-01

    The magnetic properties of Heisenberg ferromagnetic films in an external magnetic field are investigated by means of the variational cumulant expansion (VCE). The magnetization can be in principle calculated analytically as the function of the temperature and the number of atomic layers in the film to an arbitrary order of accuracy in the VCE. We calculate the spontaneous magnetization and coercivity to the third order for spin-1/2 Heisenberg films with simple cubic lattices by using a graphic technique.

  6. Multiplicity factor and diffraction geometry factor for single crystal X-ray diffraction analysis and measurement of phase content in cubic GaN/GaAs(001) epilayers

    Institute of Scientific and Technical Information of China (English)

    QU; Bo

    2001-01-01

    [1] Yang, H., Zheng, L.X., Li, J.B. et al., Cubic-phase GaN light-emitting diode, Appl. Phys. Lett., 1999, 74(17): 2498.[2] Trampert, A., Brandt, O., Yang, H. et al., Direct observation of the initial nucleation and epitaxial growth of metastable cubic GaN on GaAs(001), Appl. Phys. Lett., 1997, 70(5): 583.[3] Balakrishnan, K., Feuillet, G., Ohta, K. et al., Structural analysis of cubic GaN through X-ray pole figure generation, Jpn. J. Appl. Phys., 1997, 36(10, part 1): 6221.[4] Basu, S.N., Lei, T., Moustakas, T.D., Microstructures of GaN films deposited on (001) and (111) Si substrates using electron cyclotron resonance assisted-molecular beam epitaxy, J. Mater. Res., 1994, 9(9): 2370.[5] Powell, R.C., Lee, N.E., Kim, Y.W. et al., Heteroepitaxial wurtzite and zinc-blende structure GaN grown by reactive-ion molecular-beam epitaxy: growth kinetics, microstructure, and properties, J. Appl. Phys., 1993, 73(1): 189.[6] Camassel, J., Vicente, P., Planes, N. et al., Experimental investigation of cubic to hexagonal ratio for GaN layers deposited on 3C-SiC/Si, Phys. Stat. Sol. (b), 1999, 216: 253.[7] Sun, X.L., Yang, H., Zheng, L.X., Stability investigation of cubic GaN films grown by MOCVD on GaAs(100), Appl. Phys. Lett., 1999, 74(19 ): 2827.[8] Moret, M., Ruttenach-clur, S., Moreaud, N. et al., MOCVD growth of cubic gallium nitride: effect of V/III ratio, Phys. Stat. Sol. (a), 1999, 176: 493.[9] Qin, Z.X., Nagano, H., Sugure, Y. et al., High-resolution X-ray diffraction analysis of cubic GaN grown on (001)GaAs by RF-radical source molecular beam epitaxy, J. Crys. Growth, 1998, 189/190: 425.[10] Qin Zhixin, Kobayashi, M., Yoshikawa, A., X-ray diffraction reciprocal space and pole figure characterization of cubic GaN epitaxial layers grown on (001)GaAs by molecular beam epitaxy, J. Mater. Sci., 1999,109: 199.[11] Trampert, A., Brandt, O., Ploog, K. H., Phase transformations and phase stability in epitaxial

  7. Phase diagrams and synthesis of cubic boron nitride

    CERN Document Server

    Turkevich, V Z

    2002-01-01

    On the basis of phase equilibria, the lowest temperatures, T sub m sub i sub n , above which at high pressures cubic boron nitride crystallization from melt solution is allowable in terms of thermodynamics have been found for a number of systems that include boron nitride.

  8. Interaction of dispersed cubic phases with blood components

    DEFF Research Database (Denmark)

    Bode, J C; Kuntsche, Judith; Funari, S S;

    2013-01-01

    The interaction of aqueous nanoparticle dispersions, e.g. based on monoolein/poloxamer 407, with blood components is an important topic concerning especially the parenteral way of administration. Therefore, the influence of human and porcine plasma on dispersed cubic phases was investigated...

  9. Cubic surfaces and their invariants: Some memories of Raymond Stora

    Science.gov (United States)

    Bauer, Michel

    2016-11-01

    Cubic surfaces embedded in complex projective 3-space are a classical illustration of the use of old and new methods in algebraic geometry. Recently, they made their appearance in physics, and in particular aroused the interest of Raymond Stora, to the memory of whom these notes are dedicated, and to whom I'm very much indebted. Each smooth cubic surface has a rich geometric structure, which I review briefly, with emphasis on the 27 lines and the combinatorics of their intersections. Only elementary methods are used, relying on first order perturbation/deformation theory. I then turn to the study of the family of cubic surfaces. They depend on 20 parameters, and the action of the 15 parameter group SL4 (C) splits the family in orbits depending on 5 parameters. This takes us into the realm of (geometric) invariant theory. I review briefly the classical theorems on the structure of the ring of polynomial invariants and illustrate its many facets by looking at a simple example, before turning to the already involved case of cubic surfaces. The invariant ring was described in the 19th century. I show how to retrieve this description via counting/generating functions and character formulae.

  10. Exact solutions for the cubic-quintic nonlinear Schroedinger equation

    Energy Technology Data Exchange (ETDEWEB)

    Zhu Jiamin [Department of Physics, Zhejiang Lishui University, Lishui 323000 (China)]. E-mail: zjm64@163.com; Ma Zhengyi [Department of Physics, Zhejiang Lishui University, Lishui 323000 (China); Institute of Applied Mathematics and Mechanics, Shanghai University, Shanghai 200072 (China)

    2007-08-15

    In this paper, the cubic-quintic nonlinear Schroedinger equation is solved through the extended elliptic sub-equation method. As a consequence, many types of exact travelling wave solutions are obtained which including bell and kink profile solitary wave solutions, triangular periodic wave solutions and singular solutions.

  11. Combinatorics on Words in Symbolic Dynamics: the Antisymmetric Cubic Map

    Institute of Scientific and Technical Information of China (English)

    Wan Ji DAI; Kebo L(U); Jun WANG

    2008-01-01

    This paper is contributed to the combinatorial properties of the periodic kneading words of antisymmetric cubic maps defined on a interval.The least words of given lengths,the adjacency relations on the words of given lengths and the parity-alternative property in some sets of such words are established.

  12. A Unified Approach to Teaching Quadratic and Cubic Equations.

    Science.gov (United States)

    Ward, A. J. B.

    2003-01-01

    Presents a simple method for teaching the algebraic solution of cubic equations via completion of the cube. Shows that this method is readily accepted by students already familiar with completion of the square as a method for quadratic equations. (Author/KHR)

  13. Orientational phase transition in cubic liquid crystals with positional order

    OpenAIRE

    Pokrovsky, V.L.; Saidachmetov, P.A.

    1988-01-01

    An electric field can give rise to a shear deformation of a cubic liquid crystal with long-range positional order fixed by two plates. The critical value of the field does not depend on the size of the system and depends crucially on the orientation.

  14. An effective packing density of binary cubic crystals

    Science.gov (United States)

    Eremin, I. E.; Eremina, V. V.; Sychev, M. S.; Moiseenko, V. G.

    2015-04-01

    The methodology of effective macroscopic calculation of numerical values of internuclear distances in binary crystals of a cubic crystal system is based on the use of coefficients of the structural packing density of the crystal lattice. The possibility of combining the reference data on the main physicochemical parameters of the substance is implemented by synthesis of the corresponding mathematical models.

  15. Trapping of cubic ZnO nanocrystallites at ambient conditions

    DEFF Research Database (Denmark)

    Decremps, F.; Pellicer-Porres, J.; Datchi, F.

    2002-01-01

    Dense powder of nanocrystalline ZnO has been recovered at ambient conditions in the metastable cubic structure after a heat treatment at high pressure (15 GPa and 550 K). Combined x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) experiments have been performed to probe both long-ra...

  16. Specific heat of the simple-cubic Ising model

    NARCIS (Netherlands)

    Feng, X.; Blöte, H.W.J.

    2010-01-01

    We provide an expression quantitatively describing the specific heat of the Ising model on the simple-cubic lattice in the critical region. This expression is based on finite-size scaling of numerical results obtained by means of a Monte Carlo method. It agrees satisfactorily with series expansions

  17. Connecting the Dots Parametrically: An Alternative to Cubic Splines.

    Science.gov (United States)

    Hildebrand, Wilbur J.

    1990-01-01

    Discusses a method of cubic splines to determine a curve through a series of points and a second method for obtaining parametric equations for a smooth curve that passes through a sequence of points. Procedures for determining the curves and results of each of the methods are compared. (YP)

  18. Cubic spline approximation techniques for parameter estimation in distributed systems

    Science.gov (United States)

    Banks, H. T.; Crowley, J. M.; Kunisch, K.

    1983-01-01

    Approximation schemes employing cubic splines in the context of a linear semigroup framework are developed for both parabolic and hyperbolic second-order partial differential equation parameter estimation problems. Convergence results are established for problems with linear and nonlinear systems, and a summary of numerical experiments with the techniques proposed is given.

  19. Rheology of cubic particles suspended in a Newtonian fluid.

    Science.gov (United States)

    Cwalina, Colin D; Harrison, Kelsey J; Wagner, Norman J

    2016-05-18

    Many real-world industrial processes involve non-spherical particles suspended in a fluid medium. Knowledge of the flow behavior of these suspensions is essential for optimizing their transport properties and designing processing equipment. In the present work, we explore and report on the rheology of concentrated suspensions of cubic-shaped colloidal particles under steady and dynamic shear flow. These suspensions exhibit a rich non-Newtonian rheology that includes shear thickening and normal stress differences at high shear stresses. Scalings are proposed to connect the material properties of these suspensions of cubic particle to those measured for suspensions of spherical particles. Negative first normal stress differences indicate that lubrication hydrodynamic forces dominate the stress in the shear-thickened state. Accounting for the increased lubrication hydrodynamic interactions between the flat surfaces of the cubic particles allows for a quantitative comparison of the deviatoric stress in the shear-thickened state to that of spherical particles. New semi-empirical models for the viscosity and normal stress difference coefficients are presented for the shear-thickened state. The results of this study indicate that cubic particles offer new and unique opportunities to formulate colloidal dispersions for field-responsive materials.

  20. Infinite Face Centered Cubic Network of Identical Resistors

    CERN Document Server

    Asad, J H

    2012-01-01

    The equivalent resistance between the origin and any other lattice site, in an infinite Face Centered Cubic network consisting from identical resistors, has been expressed rationally in terms of the known value and . The asymptotic behavior is investigated, and some calculated values for the equivalent resistance are presented.

  1. Trace spaces in a pre-cubical complex

    DEFF Research Database (Denmark)

    Raussen, Martin

    In directed algebraic topology, (spaces of) directed irreversible (d)-paths are studied from a topological and from a categorical point of view. Motivated by models for concurrent computation, we study in this paper spaces of d-paths in a pre-cubical complex. Such paths are equipped with a natural...

  2. Morphosynthesis of cubic silver cages on monolithic activated carbon.

    Science.gov (United States)

    Wang, Fei; Zhao, Hong; Lai, Yijian; Liu, Siyu; Zhao, Binyuan; Ning, Yuesheng; Hu, Xiaobin

    2013-11-14

    Cubic silver cages were prepared on monolithic activated carbon (MAC) pre-absorbed with Cl(-), SO4(2-), or PO4(3-) anions. Silver insoluble salts served as templates for the morphosynthesis of silver cages. The silver ions were reduced by reductive functional groups on MAC micropores through a galvanic cell reaction mechanism.

  3. SUPERCONVERGENCE ANALYSIS FOR CUBIC TRIANGULAR ELEMENT OF THE FINITE ELEMENT

    Institute of Scientific and Technical Information of China (English)

    Qi-ding Zhu

    2000-01-01

    In this paper, we construct a projection interpolation for cubic triangular ele- ment by using othogonal expansion triangular method. We show two fundamental formulas of estimation on a special partion and obtain a superconvergence result of 1 -e order higher for the placement function and its tangential derivative on the third order Lobatto points and Gauss points on each edge of triangular element.

  4. Integrability of Lotka-Volterra Planar Complex Cubic Systems

    Science.gov (United States)

    Dukarić, Maša; Giné, Jaume

    In this paper, we study the Lotka-Volterra complex cubic systems. We obtain necessary conditions of integrability for these systems with some restriction on the parameters. The sufficiency is proved for all conditions, except one which remains open, using different methods.

  5. Global Well-Posedness for Cubic NLS with Nonlinear Damping

    KAUST Repository

    Antonelli, Paolo

    2010-11-04

    We study the Cauchy problem for the cubic nonlinear Schrödinger equation, perturbed by (higher order) dissipative nonlinearities. We prove global in-time existence of solutions for general initial data in the energy space. In particular we treat the energy-critical case of a quintic dissipation in three space dimensions. © Taylor & Francis Group, LLC.

  6. Study of the crystallographic phase change on copper (I) selenide thin films prepared through chemical bath deposition by varying the pH of the solution

    Science.gov (United States)

    Sandoval-Paz, M. G.; Rodríguez, C. A.; Porcile-Saavedra, P. F.; Trejo-Cruz, C.

    2016-07-01

    Copper (I) selenide thin films with orthorhombic and cubic structure were deposited on glass substrates by using the chemical bath deposition technique. The effects of the solution pH on the films growth and subsequently the structural, optical and electrical properties of the films were studied. Films with orthorhombic structure were obtained from baths wherein both metal complex and hydroxide coexist; while films with cubic structure were obtained from baths where the metal hydroxide there is no present. The structural modifications are accompanied by changes in bandgap energy, morphology and electrical resistivity of the films.

  7. Film Reviews.

    Science.gov (United States)

    Lance, Larry M.; Atwater, Lynn

    1987-01-01

    Reviews four Human Sexuality films and videos. These are: "Personal Decisions" (Planned Parenthood Federation of America, 1985); "The Touch Film" (Sterling Production, 1986); "Rethinking Rape" (Film Distribution Center, 1985); "Not A Love Story" (National Film Board of Canada, 1981). (AEM)

  8. Radiation hardness studies of n{sup +}-in-n planar pixel sensors for the ATLAS upgrades

    Energy Technology Data Exchange (ETDEWEB)

    Altenheiner, S.; Goessling, C.; Jentzsch, J.; Klingenberg, R. [Lehrstuhl fuer Experimentelle Physik IV, TU Dortmund, 44221 Dortmund (Germany); Muenstermann, D., E-mail: Daniel.Muenstermann@TU-Dortmund.de [Lehrstuhl fuer Experimentelle Physik IV, TU Dortmund, 44221 Dortmund (Germany); Rummler, A.; Troska, G.; Wittig, T. [Lehrstuhl fuer Experimentelle Physik IV, TU Dortmund, 44221 Dortmund (Germany)

    2011-12-01

    The ATLAS experiment at the LHC is planning upgrades of its pixel detector to cope with the luminosity increase foreseen in the coming years within the transition from LHC to Super-LHC (SLHC/HL-LHC). Associated with the increase in instantaneous luminosity is a rise of the target integrated luminosity from 730 to about 3000 fb{sup -1} which directly translates into significantly higher radiation damage. These upgrades consist of the installation of a 4th pixel layer, the insertable b-layer IBL, with a mean sensor radius of only 32 mm from the beam axis, before 2016/17. In addition, the complete pixel detector will be exchanged before 2020/21. Being very close to the beam, the radiation damage of the IBL sensors might be as high as 5 Multiplication-Sign 10{sup 15}n{sub eq}cm{sup -2} at their end-of-life. The total fluence of the innermost pixel layer after the SLHC upgrade might even reach 2 Multiplication-Sign 10{sup 16}n{sub eq}cm{sup -2}. To investigate the radiation hardness and suitability of the current ATLAS pixel sensors for these fluences, n{sup +}-in-n silicon pixel sensors from the ATLAS Pixel production have been irradiated by reactor neutrons to the IBL design fluence and been tested with pions at the SPS and with electrons from a {sup 90}Sr source in the laboratory. The collected charge after IBL fluences was found to exceed 10 000 electrons per MIP at 1 kV of bias voltage which is in agreement with data collected with strip sensors. After SLHC fluences, still reliable operation of the devices could be observed with a collected charge of more than 5000 electrons per MIP.

  9. Cubic ideal ferromagnets at low temperature and weak magnetic field

    Science.gov (United States)

    Hofmann, Christoph P.

    2017-04-01

    The low-temperature series for the free energy density, pressure, magnetization and susceptibility of cubic ideal ferromagnets in weak external magnetic fields are discussed within the effective Lagrangian framework up to three loops. The structure of the simple, body-centered, and face-centered cubic lattice is taken into account explicitly. The expansion involves integer and half-integer powers of the temperature. The corresponding coefficients depend on the magnetic field and on low-energy effective constants that can be expressed in terms of microscopic quantities. Our formulas may also serve as efficiency or consistency check for other techniques like Green's function methods, where spurious terms in the low-temperature expansion have appeared. We explore the sign and magnitude of the spin-wave interaction in the pressure, magnetization and susceptibility, and emphasize that our effective field theory approach is fully systematic and rigorous.

  10. Counting real cubics with passage/tangency conditions

    CERN Document Server

    Lanzat, Sergei

    2010-01-01

    We study the following question: given a set of seven points and an immersed curve in the real plane R^2, all in general position, how many real rational nodal plane cubics pass through these points and are tangent to this curve. We count each such cubic with a certain sign, and present an explicit formula for their algebraic number. This number is preserved under small regular homotopies of the curve, but jumps (in a well-controlled way) when in the process of homotopy we pass a certain singular discriminant. We discuss the relation of such enumerative problems with finite type invariants. Our approach is based on maps of configuration spaces and the intersection theory in the spirit of classical algebraic topology.

  11. Reversible Nanoparticle Cubic Lattices in Blue Phase Liquid Crystals.

    Science.gov (United States)

    Gharbi, Mohamed Amine; Manet, Sabine; Lhermitte, Julien; Brown, Sarah; Milette, Jonathan; Toader, Violeta; Sutton, Mark; Reven, Linda

    2016-03-22

    Blue phases (BPs), a distinct class of liquid crystals (LCs) with 3D periodic ordering of double twist cylinders involving orthogonal helical director twists, have been theoretically studied as potential templates for tunable colloidal crystals. Here, we report the spontaneous formation of thermally reversible, cubic crystal nanoparticle (NP) assemblies in BPs. Gold NPs, functionalized to be highly miscible in cyanobiphenyl-based LCs, were dispersed in BP mixtures and characterized by polarized optical microscopy and synchrotron small-angle X-ray scattering (SAXS). The NPs assemble by selectively migrating to periodic strong trapping sites in the BP disclination lines. The NP lattice, remarkably robust given the small particle size (4.5 nm diameter), is commensurate with that of the BP matrix. At the BP I to BP II phase transition, the NP lattice reversibly switches between two different cubic structures. The simultaneous presence of two different symmetries in a single material presents an interesting opportunity to develop novel dynamic optical materials.

  12. Highly Aminated Mesoporous Silica Nanoparticles with Cubic Pore Structure

    KAUST Repository

    Suteewong, Teeraporn

    2011-01-19

    Mesoporous silica with cubic symmetry has attracted interest from researchers for some time. Here, we present the room temperature synthesis of mesoporous silica nanoparticles possessing cubic Pm3n symmetry with very high molar ratios (>50%) of 3-aminopropyl triethoxysilane. The synthesis is robust allowing, for example, co-condensation of organic dyes without loss of structure. By means of pore expander molecules, the pore size can be enlarged from 2.7 to 5 nm, while particle size decreases. Adding pore expander and co-condensing fluorescent dyes in the same synthesis reduces average particle size further down to 100 nm. After PEGylation, such fluorescent aminated mesoporous silica nanoparticles are spontaneously taken up by cells as demonstrated by fluorescence microscopy.

  13. The Piecewise Cubic Method (PCM) for computational fluid dynamics

    Science.gov (United States)

    Lee, Dongwook; Faller, Hugues; Reyes, Adam

    2017-07-01

    We present a new high-order finite volume reconstruction method for hyperbolic conservation laws. The method is based on a piecewise cubic polynomial which provides its solutions a fifth-order accuracy in space. The spatially reconstructed solutions are evolved in time with a fourth-order accuracy by tracing the characteristics of the cubic polynomials. As a result, our temporal update scheme provides a significantly simpler and computationally more efficient approach in achieving fourth order accuracy in time, relative to the comparable fourth-order Runge-Kutta method. We demonstrate that the solutions of PCM converges at fifth-order in solving 1D smooth flows described by hyperbolic conservation laws. We test the new scheme on a range of numerical experiments, including both gas dynamics and magnetohydrodynamics applications in multiple spatial dimensions.

  14. The Piecewise Cubic Method (PCM) for Computational Fluid Dynamics

    CERN Document Server

    Lee, Dongwook; Reyes, Adam

    2016-01-01

    We present a new high-order finite volume reconstruction method for hyperbolic conservation laws. The method is based on a piecewise cubic polynomial which provides its solutions a fifth-order accuracy in space. The spatially reconstructed solutions are evolved in time with a fourth-order accuracy by tracing the characteristics of the cubic polynomials. As a result, our temporal update scheme provides a significantly simpler and computationally more efficient approach in achieving fourth order accuracy in time, relative to the comparable fourth-order Runge-Kutta method. We demonstrate that the solutions of PCM converges in fifth-order in solving 1D smooth flows described by hyperbolic conservation laws. We test the new scheme in a range of numerical experiments, including both gas dynamics and magnetohydrodynamics applications in multiple spatial dimensions.

  15. Cubic Composite Sensor with Photodiodes for Tracking Solar Orientation

    Directory of Open Access Journals (Sweden)

    Yong-Nong Chang

    2013-01-01

    Full Text Available A cubic composite solar sensor with photo diode is proposed for tracking the relative solar orientation. The proposed solar sensor composes of five photodiode detectors which are placed on the front, rear, left, right, and horizontal facets in a cubic body, respectively. The solar detectors placed on five facets can detect solar power of different facets. Based on the geometric coordinate transformation principle, the relationship equations of solar light orientation between measured powers with respect to various facets can be conducted. As a result, the solar orientation can be precisely achieved without needing any assistance of electronic compass and extra orientation angle corrector. Eventually, the relative solar light orientation, the elevation angle, and azimuth angle of the solar light can be measured precisely.

  16. Nonlinear optical imaging of defects in cubic silicon carbide epilayers.

    Science.gov (United States)

    Hristu, Radu; Stanciu, Stefan G; Tranca, Denis E; Matei, Alecs; Stanciu, George A

    2014-06-11

    Silicon carbide is one of the most promising materials for power electronic devices capable of operating at extreme conditions. The widespread application of silicon carbide power devices is however limited by the presence of structural defects in silicon carbide epilayers. Our experiment demonstrates that optical second harmonic generation imaging represents a viable solution for characterizing structural defects such as stacking faults, dislocations and double positioning boundaries in cubic silicon carbide layers. X-ray diffraction and optical second harmonic rotational anisotropy were used to confirm the growth of the cubic polytype, atomic force microscopy was used to support the identification of silicon carbide defects based on their distinct shape, while second harmonic generation microscopy revealed the detailed structure of the defects. Our results show that this fast and noninvasive investigation method can identify defects which appear during the crystal growth and can be used to certify areas within the silicon carbide epilayer that have optimal quality.

  17. Global Sufficient Optimality Conditions for a Special Cubic Minimization Problem

    Directory of Open Access Journals (Sweden)

    Xiaomei Zhang

    2012-01-01

    Full Text Available We present some sufficient global optimality conditions for a special cubic minimization problem with box constraints or binary constraints by extending the global subdifferential approach proposed by V. Jeyakumar et al. (2006. The present conditions generalize the results developed in the work of V. Jeyakumar et al. where a quadratic minimization problem with box constraints or binary constraints was considered. In addition, a special diagonal matrix is constructed, which is used to provide a convenient method for justifying the proposed sufficient conditions. Then, the reformulation of the sufficient conditions follows. It is worth noting that this reformulation is also applicable to the quadratic minimization problem with box or binary constraints considered in the works of V. Jeyakumar et al. (2006 and Y. Wang et al. (2010. Finally some examples demonstrate that our optimality conditions can effectively be used for identifying global minimizers of the certain nonconvex cubic minimization problem.

  18. Plasma simulation with the Differential Algebraic Cubic Interpolated Propagation scheme

    Energy Technology Data Exchange (ETDEWEB)

    Utsumi, Takayuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    A computer code based on the Differential Algebraic Cubic Interpolated Propagation scheme has been developed for the numerical solution of the Boltzmann equation for a one-dimensional plasma with immobile ions. The scheme advects the distribution function and its first derivatives in the phase space for one time step by using a numerical integration method for ordinary differential equations, and reconstructs the profile in phase space by using a cubic polynomial within a grid cell. The method gives stable and accurate results, and is efficient. It is successfully applied to a number of equations; the Vlasov equation, the Boltzmann equation with the Fokker-Planck or the Bhatnagar-Gross-Krook (BGK) collision term and the relativistic Vlasov equation. The method can be generalized in a straightforward way to treat cases such as problems with nonperiodic boundary conditions and higher dimensional problems. (author)

  19. Quantum spectra and classical periodic orbit in the cubic billiard

    Institute of Scientific and Technical Information of China (English)

    Dehua Wang; Yongjiang Yu; Shenglu Lin

    2006-01-01

    Quantum billiards have attracted much interest in many fields. People have made a lot of researches on the two-dimensional (2D) billiard systems. Contrary to the 2D billiard, due to the complication of its classical periodic orbits, no one has studied the correspondence between the quantum spectra and the classical orbits of the three-dimensional (3D) billiards. Taking the cubic billiard as an example, using the periodic orbit theory, we find the periodic orbit of the cubic billiard and study the correspondence between the quantum spectra and the length of the classical orbits in 3D system. The Fourier transformed spectrum of this system has allowed direct comparison between peaks in such plot and the length of the periodic orbits, which verifies the correctness of the periodic orbit theory. This is another example showing that semiclassical method provides a bridge between quantum and classical mechanics.

  20. Quantum Phase Transitions in Anti-ferromagnetic Planar Cubic Lattices

    CERN Document Server

    Wellard, C J; Wellard, Cameron; Orus, Roman

    2004-01-01

    Motivated by its relation to an NP-hard problem we analyze the ground state properties of anti-ferromagnetic Ising-spin networks in planar cubic lattices under the action of homogeneous transverse and longitudinal magnetic fields. We consider different instances of the cubic geometry and find a set of quantum phase transitions for each one of the systems, which we characterize by means of entanglement behavior and majorization theory. Entanglement scaling at the critical region is in agreement with results arising from conformal symmetry, therefore even the simplest planar systems can display very large amounts of quantum correlation. No conclusion can be made as to the scaling behavior of the minimum energy gap, with the data allowing equally good fits to exponential and power law decays. Analysis of entanglement and especially of majorization instead of the energy spectrum proves to be a good way of detecting quantum phase transitions in highly frustrated configurations.

  1. Higher-Order Approximation of Cubic-Quintic Duffing Model

    DEFF Research Database (Denmark)

    Ganji, S. S.; Barari, Amin; Babazadeh, H.

    2011-01-01

    We apply an Artificial Parameter Lindstedt-Poincaré Method (APL-PM) to find improved approximate solutions for strongly nonlinear Duffing oscillations with cubic-quintic nonlinear restoring force. This approach yields simple linear algebraic equations instead of nonlinear algebraic equations...... without analytical solution which makes it a unique solution. It is demonstrated that this method works very well for the whole range of parameters in the case of the cubic-quintic oscillator, and excellent agreement of the approximate frequencies with the exact one has been observed and discussed....... Moreover, it is not limited to the small parameter such as in the classical perturbation method. Interestingly, this study revealed that the relative error percentage in the second-order approximate analytical period is less than 0.042% for the whole parameter values. In addition, we compared...

  2. 3D Medical Image Interpolation Based on Parametric Cubic Convolution

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the process of display, manipulation and analysis of biomedical image data, they usually need to be converted to data of isotropic discretization through the process of interpolation, while the cubic convolution interpolation is widely used due to its good tradeoff between computational cost and accuracy. In this paper, we present a whole concept for the 3D medical image interpolation based on cubic convolution, and the six methods, with the different sharp control parameter, which are formulated in details. Furthermore, we also give an objective comparison for these methods using data sets with the different slice spacing. Each slice in these data sets is estimated by each interpolation method and compared with the original slice using three measures: mean-squared difference, number of sites of disagreement, and largest difference. According to the experimental results, we present a recommendation for 3D medical images under the different situations in the end.

  3. Experimental core electron density of cubic boron nitride

    DEFF Research Database (Denmark)

    Wahlberg, Nanna; Bindzus, Niels; Bjerg, Lasse

    candidate because of its many similarities with diamond: bonding pattern in the extended network structure, hardness, and the quality of the crystallites.3 However, some degree ionic interaction is a part of the bonding in boron nitride, which is not present in diamond. By investigating the core density...... beyond multipolar modeling of the valence density. As was recently shown in a benchmark study of diamond by Bindzus et al.1 The next step is to investigate more complicated chemical bonding motives, to determine the effect of bonding on the core density. Cubic boron nitride2 lends itself as a perfect...... in boron nitride we may obtain a deeper understanding of the effect of bonding on the total density. We report here a thorough investigation of the charge density of cubic boron nitride with a detailed modelling of the inner atom charge density. By combining high resolution powder X-ray diffraction data...

  4. Band offset in zinc oxy-sulfide/cubic-tin sulfide interface from X-ray photoelectron spectroscopy

    Science.gov (United States)

    K. C., Sanal; Nair, P. K.; Nair, M. T. S.

    2017-02-01

    Zinc oxy-sulfide, ZnOxS1-x, has been found to provide better band alignment in thin film solar cells of tin sulfide of orthorhombic crystalline structure. Here we examine ZnOxS1-x/SnS-CUB interface, in which the ZnOxS1-x thin film was deposited by radio frequency (rf) magnetron sputtering on SnS thin film of cubic (CUB) crystalline structure with a band gap (Eg) of 1.72 eV, obtained via chemical deposition. X-ray photoelectron spectroscopy provides the valence band maxima of the materials and hence places the conduction band offset of 0.41 eV for SnS-CUB/ZnO0.27S0.73 and -0.28 eV for SnS-CUB/ZnO0.88S0.12 interfaces. Thin films of ZnOxS1-x with 175-240 nm in thickness were deposited from targets prepared with different ZnO to ZnS molar ratios. With the target of molar ratio of 1:13.4, the thin films are of composition ZnO0.27S0.73 with hexagonal crystalline structure and with that of 1:1.7 ratio, it is ZnO0.88S0.12. The optical band gap of the ZnOxS1-x thin films varies from 2.90 eV to 3.21 eV as the sulfur to zinc ratio in the film increases from 0.12:1 to 0.73:1 as determined from X-ray diffraction patterns. Thus, band offsets sought for absorber materials and zinc oxy-sulfide in solar cells may be achieved through a choice of ZnO:ZnS ratio in the sputtering target.

  5. Quadratic and Cubic Nonlinear Oscillators with Damping and Their Applications

    Science.gov (United States)

    Li, Jibin; Feng, Zhaosheng

    We apply the qualitative theory of dynamical systems to study exact solutions and the dynamics of quadratic and cubic nonlinear oscillators with damping. Under certain parametric conditions, we also consider the van der Waals normal form, Chaffee-Infante equation, compound Burgers-KdV equation and Burgers-KdV equation for explicit representations of kink-profile wave solutions and unbounded traveling wave solutions.

  6. The Number of Real Roots of a Cubic Equation

    Science.gov (United States)

    Kavinoky, Richard; Thoo, John B.

    2008-01-01

    To find the number of distinct real roots of the cubic equation (1) x[caret]3 + bx[caret]2 + cx + d = 0, we could attempt to solve the equation. Fortunately, it is easy to tell the number of distinct real roots of (1) without having to solve the equation. The key is the discriminant. The discriminant of (1) appears in Cardan's (or Cardano's) cubic…

  7. A highly ordered cubic mesoporous silica/graphene nanocomposite

    Science.gov (United States)

    Lee, Chang-Wook; Roh, Kwang Chul; Kim, Kwang-Bum

    2013-09-01

    A highly ordered cubic mesoporous silica (KIT-6)/graphene nanocomposite and 2D KIT-6 nanoflakes were synthesized using a novel synthesis methodology. The non-ionic triblock copolymer, P123, played a dual role as a structure-directing agent in the formation of the cubic mesoporous structure and as a cross-linking agent between mesoporous silica and graphene. The prepared (KIT-6)/graphene nanocomposite could act as a template for the preparation of mesoporous material/graphene nanocomposites.A highly ordered cubic mesoporous silica (KIT-6)/graphene nanocomposite and 2D KIT-6 nanoflakes were synthesized using a novel synthesis methodology. The non-ionic triblock copolymer, P123, played a dual role as a structure-directing agent in the formation of the cubic mesoporous structure and as a cross-linking agent between mesoporous silica and graphene. The prepared (KIT-6)/graphene nanocomposite could act as a template for the preparation of mesoporous material/graphene nanocomposites. Electronic supplementary information (ESI) available: S1: TEM images of disordered mesoporous silica/graphene nanocomposite; S2: TEM images of KIT-6/GO nanocomposite; S3: Thermogravimetric analysis of KIT-6/GO and KG-400-700; S4: SEM and TEM images of KIT-6; S5: Low angle XRD, Raman spectra, N2 adsorption isotherms, pore size distribution and photographic images of the prepared samples; S6: TEM image and N2 adsorption isotherms of mesoporous carbon/graphene nanocomposite; S7: XPS C1s spectra of the prepared samples. See DOI: 10.1039/c3nr03108j

  8. Multiscale Modeling of Point and Line Defects in Cubic Lattices

    Science.gov (United States)

    2007-01-01

    and discli- nations with finite micropolar elastoplasticity . Int. J. Plasticity. 22:210–256, 2006. 56. Menzel, A., and Steinmann, P., On the contin...Voyiadjis, G. Z., A finite strain plastic- damage model for high velocity impact using combined viscosity and gradient localization limiters: Part I...Theoretical for- mulation. Int. J. Damage Mech. 15:293–334, 2006. 58. Milstein, F., and Chantasiriwan, S,. Theoretical study of the response of 12 cubic

  9. INTEGRABILITY AND LINEARIZABILITY FOR A CLASS OF CUBIC KOLMOGOROV SYSTEMS

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The integrability and linearizability for a class of cubic Kolmogorov systems are studied. A recursive formula to compute the saddle quantities of the systems is deduced firstly, and integrable conditions for the systems are obtained. Then a recursive formula to compute the coefficients of the normal form for saddle points of the systems is also applied. Finally linearizable conditions of the origin for the systems are given. Both formulas to find necessary conditions are all linear and readily done using c...

  10. Infinite Body Centered Cubic Network of Identical Resistors

    CERN Document Server

    Asad, J H

    2013-01-01

    We express the equivalent resistance between the origin and any other lattice site in an infinite Body Centered Cubic (BCC) network consisting of identical resistors each of resistance R rationally in terms of known values and . The equivalent resistance is then calculated. Finally, for large separation between the origin and the lattice site two asymptotic formulas for the resistance are presented and some numerical results with analysis are given.

  11. Lipidic cubic phase injector facilitates membrane protein serial femtosecond crystallography.

    Science.gov (United States)

    Weierstall, Uwe; James, Daniel; Wang, Chong; White, Thomas A; Wang, Dingjie; Liu, Wei; Spence, John C H; Bruce Doak, R; Nelson, Garrett; Fromme, Petra; Fromme, Raimund; Grotjohann, Ingo; Kupitz, Christopher; Zatsepin, Nadia A; Liu, Haiguang; Basu, Shibom; Wacker, Daniel; Han, Gye Won; Katritch, Vsevolod; Boutet, Sébastien; Messerschmidt, Marc; Williams, Garth J; Koglin, Jason E; Marvin Seibert, M; Klinker, Markus; Gati, Cornelius; Shoeman, Robert L; Barty, Anton; Chapman, Henry N; Kirian, Richard A; Beyerlein, Kenneth R; Stevens, Raymond C; Li, Dianfan; Shah, Syed T A; Howe, Nicole; Caffrey, Martin; Cherezov, Vadim

    2014-01-01

    Lipidic cubic phase (LCP) crystallization has proven successful for high-resolution structure determination of challenging membrane proteins. Here we present a technique for extruding gel-like LCP with embedded membrane protein microcrystals, providing a continuously renewed source of material for serial femtosecond crystallography. Data collected from sub-10-μm-sized crystals produced with less than 0.5 mg of purified protein yield structural insights regarding cyclopamine binding to the Smoothened receptor.

  12. Rotary Ultrasonic Machining of Poly-Crystalline Cubic Boron Nitride

    OpenAIRE

    2014-01-01

    Poly-crystalline cubic boron nitride (PCBN) is one of the hardest material. Generally, so hard materials could not be machined by conventional machining methods. Therefore, for this purpose, advanced machining methods have been designed. Rotary ultrasonic machining (RUM) is included among them. RUM is based on abrasive removing mechanism of ultrasonic vibrating diamond particles, which are bonded on active part of rotating tool. It is suitable especially for machining hard and brittle materia...

  13. Bicontinuous cubic liquid crystalline nanoparticles for oral delivery of Doxorubicin

    DEFF Research Database (Denmark)

    Swarnakar, Nitin K; Thanki, Kaushik; Jain, Sanyog

    2014-01-01

    PURPOSE: The present study explores the potential of bicontinous cubic liquid crystalline nanoparticles (LCNPs) for improving therapeutic potential of doxorubicin. METHODS: Phytantriol based Dox-LCNPs were prepared using hydrotrope method, optimized for various formulation components, process...... variables and lyophilized. Structural elucidation of the reconstituted formulation was performed using HR-TEM and SAXS analysis. The developed formulation was subjected to exhaustive cell culture experiments for delivery potential (Caco-2 cells) and efficacy (MCF-7 cells). Finally, in vivo pharmacokinetics...

  14. The traveling salesman problem on cubic and subcubic graphs

    CERN Document Server

    Boyd, Sylvia; van der Ster, Suzanne; Stougie, Leen

    2011-01-01

    We study the Travelling Salesman Problem (TSP) on the metric completion of cubic and subcubic graphs, which is known to be NP-hard. The problem is of interest because of its relation to the famous 4/3 conjecture for metric TSP, which says that the integrality gap, i.e., the worst case ratio between the optimal values of the TSP and its linear programming relaxation (the subtour elimination relaxation), is 4/3. We present the first algorithm for cubic graphs with approximation ratio 4/3. The proof uses polyhedral techniques in a surprising way, which is of independent interest. In fact we prove constructively that for any cubic graph on $n$ vertices a tour of length 4n/3-2 exists, which also implies the 4/3 conjecture, as an upper bound, for this class of graph-TSP. Recently, M\\"omke and Svensson presented a randomized algorithm that gives a 1.461-approximation for graph-TSP on general graphs and as a side result a 4/3-approximation algorithm for this problem on subcubic graphs, also settling the 4/3 conjectur...

  15. Packing of nonoverlapping cubic particles: Computational algorithms and microstructural characteristics.

    Science.gov (United States)

    Malmir, Hessam; Sahimi, Muhammad; Tabar, M Reza Rahimi

    2016-12-01

    Packing of cubic particles arises in a variety of problems, ranging from biological materials to colloids and the fabrication of new types of porous materials with controlled morphology. The properties of such packings may also be relevant to problems involving suspensions of cubic zeolites, precipitation of salt crystals during CO_{2} sequestration in rock, and intrusion of fresh water in aquifers by saline water. Not much is known, however, about the structure and statistical descriptors of such packings. We present a detailed simulation and microstructural characterization of packings of nonoverlapping monodisperse cubic particles, following up on our preliminary results [H. Malmir et al., Sci. Rep. 6, 35024 (2016)2045-232210.1038/srep35024]. A modification of the random sequential addition (RSA) algorithm has been developed to generate such packings, and a variety of microstructural descriptors, including the radial distribution function, the face-normal correlation function, two-point probability and cluster functions, the lineal-path function, the pore-size distribution function, and surface-surface and surface-void correlation functions, have been computed, along with the specific surface and mean chord length of the packings. The results indicate the existence of both spatial and orientational long-range order as the the packing density increases. The maximum packing fraction achievable with the RSA method is about 0.57, which represents the limit for a structure similar to liquid crystals.

  16. Dry Powder Precursors of Cubic Liquid Crystalline Nanoparticles (cubosomes)

    Science.gov (United States)

    Spicer, Patrick T.; Small, William B.; Small, William B.; Lynch, Matthew L.; Burns, Janet L.

    2002-08-01

    Cubosomes are dispersed nanostructured particles of cubic phase liquid crystal that have stimulated significant research interest because of their potential for application in controlled-release and drug delivery. Despite the interest, cubosomes can be difficult to fabricate and stabilize with current methods. Most of the current work is limited to liquid phase processes involving high shear dispersion of bulk cubic liquid crystalline material into sub-micron particles, limiting application flexibility. In this work, two types of dry powder cubosome precursors are produced by spray-drying: (1) starch-encapsulated monoolein is produced by spray-drying a dispersion of cubic liquid crystalline particles in an aqueous starch solution and (2) dextran-encapsulated monoolein is produced by spray-drying an emulsion formed by the ethanol-dextran-monoolein-water system. The encapsulants are used to decrease powder cohesion during drying and to act as a soluble colloidal stabilizer upon hydration of the powders. Both powders are shown to form (on average) 0.6 μm colloidally-stable cubosomes upon addition to water. However, the starch powders have a broader particle size distribution than the dextran powders because of the relative ease of spraying emulsions versus dispersions. The developed processes enable the production of nanostructured cubosomes by end-users rather than just specialized researchers and allow tailoring of the surface state of the cubosomes for broader application.

  17. Packing of nonoverlapping cubic particles: Computational algorithms and microstructural characteristics

    Science.gov (United States)

    Malmir, Hessam; Sahimi, Muhammad; Tabar, M. Reza Rahimi

    2016-12-01

    Packing of cubic particles arises in a variety of problems, ranging from biological materials to colloids and the fabrication of new types of porous materials with controlled morphology. The properties of such packings may also be relevant to problems involving suspensions of cubic zeolites, precipitation of salt crystals during CO2 sequestration in rock, and intrusion of fresh water in aquifers by saline water. Not much is known, however, about the structure and statistical descriptors of such packings. We present a detailed simulation and microstructural characterization of packings of nonoverlapping monodisperse cubic particles, following up on our preliminary results [H. Malmir et al., Sci. Rep. 6, 35024 (2016), 10.1038/srep35024]. A modification of the random sequential addition (RSA) algorithm has been developed to generate such packings, and a variety of microstructural descriptors, including the radial distribution function, the face-normal correlation function, two-point probability and cluster functions, the lineal-path function, the pore-size distribution function, and surface-surface and surface-void correlation functions, have been computed, along with the specific surface and mean chord length of the packings. The results indicate the existence of both spatial and orientational long-range order as the the packing density increases. The maximum packing fraction achievable with the RSA method is about 0.57, which represents the limit for a structure similar to liquid crystals.

  18. Integer roots of quadratic and cubic polynomials with integer coefficients

    CERN Document Server

    Zelator, Konstantine

    2011-01-01

    The subject matter of this work is quadratic and cubic polynomial functions with integer coefficients;and all of whose roots are integers. The material of this work is directed primarily at educators,students,and teachers of mathematics,grades K12 to K20.The results of this work are expressed in Theorems3,4,and5. Of these theorems, Theorem3, is the one that most likely, the general reader of this article will have some familiarity with.In Theorem3, precise coefficient conditions are given;in order that a quadratic trinomial(with integer) have two integer roots or zeros.On the other hand, Theorems4 and5 are largely unfamiliar territory. In Theorem4, precise coefficient conditions are stated; for a monic cubic polynomial to have a double(i.e.of multiplicity 2) integer root, and a single integer root(i.e.of multiplicity 1).The entire family of such cubics can be described in terms of four groups or subfamilies; each such group being a two-integer parameter subfamily. In Theorem5, a one-integer parameter family o...

  19. Arithmetic Problems in Cubic and Quartic Function Fields

    CERN Document Server

    Bembom, Tobias

    2010-01-01

    One of the main themes in this thesis is the description of the signature of both the infinite place and the finite places in cubic function fields of any characteristic and quartic function fields of characteristic at least 5. For these purposes, we provide a new theory which can be applied to cubic and quartic function fields and to even higher dimensional function fields. One of the striking advantages of this theory to other existing methods is that is does not use the concept of p-adic completions and we can dispense of Cardano's formulae. Another key result comprises the construction of cubic function fields of unit rank 1 and 2, with an obvious fundamental system. One of the main ingredients for such constructions is the definition of the maximum value. This definition is new and very prolific in the context of finding fundamental systems. We conclude the thesis with miscellaneous results on the divisor class number h, including a new approach for finding divisors of h.

  20. Dynamic properties of the cubic nonlinear Schr(o)dinger equation by symplectic method

    Institute of Scientific and Technical Information of China (English)

    Liu Xue-Shen; Wei Jia-Yu; Ding Pei-Zhu

    2005-01-01

    The dynamic properties of a cubic nonlinear Schrodinger equation are investigated numerically by using the symplectic method with different space approximations. The behaviours of the cubic nonlinear Schrodinger equation are discussed with different cubic nonlinear parameters in the harmonically modulated initial condition. We show that the conserved quantities will be preserved for long-time computation but the system will exhibit different dynamic behaviours in space difference approximation for the strong cubic nonlinearity.

  1. Film/NotFilm

    OpenAIRE

    Willems, Gertjan

    2016-01-01

    Although Samuel Beckett (1906-1989) showed a genuine interest in audio-visual media in his fascinating and innovative radio plays and television works, and in 1936 even wrote a letter to Sergei Eisenstein to be accepted to the famous Soviet film school VGIK, the 22-minute Film (1965) was his only venture into cinema. Beckett conceived the film, wrote the screenplay, supervised the production and, as one of the film’s crew members recalled and as the director Alan Schneider himself acknowledge...

  2. Thin Films

    Directory of Open Access Journals (Sweden)

    M. Benmouss

    2003-01-01

    the optical absorption are consistent with the film color changes. Finally, the optical and electrochromic properties of the films prepared by this method are compared with those of our sputtered films already studied and with other works.

  3. Tribological properties of the two-step thermally deposited chromium films

    NARCIS (Netherlands)

    Lazauskas, A.; Baltrusaitis, J.; Grigaliunas, V.; Baltusnikas, A.; Abakeviciene, B.; Polcar, T.

    2013-01-01

    Chromium thin films were prepared on glass substrate via a two-step thermal deposition and their structural, chemical and tribological properties were determined. The X-ray diffraction pattern of the two-step thermally deposited chromium film showed the presence of well-defined body-centered cubic C

  4. Vacancy-induced mechanical stabilization of cubic tungsten nitride

    Science.gov (United States)

    Balasubramanian, Karthik; Khare, Sanjay; Gall, Daniel

    2016-11-01

    First-principles methods are employed to determine the structural, mechanical, and thermodynamic reasons for the experimentally reported cubic WN phase. The defect-free rocksalt phase is both mechanically and thermodynamically unstable, with a negative single crystal shear modulus C44=-86 GPa and a positive enthalpy of formation per formula unit Hf=0.623 eV with respect to molecular nitrogen and metallic W. In contrast, WN in the NbO phase is stable, with C44=175 GPa and Hf=-0.839 eV . A charge distribution analysis reveals that the application of shear strain along [100] in rocksalt WN results in an increased overlap of the t2 g orbitals which causes electron migration from the expanded to the shortened W-W bond axes, yielding a negative shear modulus due to an energy reduction associated with new bonding states 8.1-8.7 eV below the Fermi level. A corresponding shear strain in WN in the NbO phase results in an energy increase and a positive shear modulus. The mechanical stability transition from the NaCl to the NbO phase is explored using supercell calculations of the NaCl structure containing Cv=0 %-25 % cation and anion vacancies, while keeping the N-to-W ratio constant at unity. The structure is mechanically unstable for Cvconcentration, the isotropic elastic modulus E of cubic WN is zero, but increases steeply to E =445 GPa for Cv=10 % , and then less steeply to E =561 GPa for Cv=25 % . Correspondingly, the hardness estimated using Tian's model increases from 0 to 15 to 26 GPa as Cv increases from 5% to 10% to 25%, indicating that a relatively small vacancy concentration stabilizes the cubic WN phase and that the large variations in reported mechanical properties of WN can be attributed to relatively small changes in Cv.

  5. Cubic Phases, Cubosomes and Ethosomes for Cutaneous Application.

    Science.gov (United States)

    Esposito, Elisabetta; Drechsler, Markus; Nastruzzi, Claudio; Cortesi, Rita

    2016-01-01

    Cutaneous administration represents a good strategy to treat skin diseases, avoiding side effects related to systemic administration. Apart from conventional therapy, based on the use of semi-solid formulation such as gel, ointments and creams, recently the use of specialized delivery systems based on lipid has been taken hold. This review provides an overview about the use of cubic phases, cubosomes and ethosomes, as lipid systems recently proposed to treat skin pathologies. In addition in the final part of the review cubic phases, cubosomes and ethosomes are compared to solid lipid nanoparticles and lecithin organogel with respect to their potential as delivery systems for cutaneous application. It has been reported that lipid nanosystems are able to dissolve and deliver active molecules in a controlled fashion, thereby improving their bioavailability and reducing side-effects. Particularly lipid matrixes are characterized by skin affinity and biocompatibility allowing their application on skin. Indeed, after cutaneous administration, the lipid matrix of cubic phases and cubosomes coalesces with the lipids of the stratum comeum and leads to the formation of a lipid depot from which the drug associated to the nanosystem can be released in the deeper skin strata in a controlled manner. Ethosomes are characterized by a malleable structure that promotes their interaction with skin, improving their potential as skin delivery systems with respect to liposomes. Also in the case of solid lipid nanoparticles it has been suggested a deep interaction between lipid matrix and skin strata that endorses sustained and prolonged drug release. Concerning lecithin organogel, the peculiar structure of this system, where lecithin exerts a penetration enhancer role, allows a deep interaction with skin strata, promoting the transdermal absorption of the encapsulated drugs.

  6. Cubature Formula and Interpolation on the Cubic Domain

    Institute of Scientific and Technical Information of China (English)

    Huiyuan Li; Jiachang Sun; Yuan Xu

    2009-01-01

    Several cubature formulas on the cubic domains are derived using the dis-crete Fourier analysis associated with lattice tiling, as developed in [10]. The main results consist of a new derivation of the Gaussian type cubature for the product Cheby-shev weight functions and associated interpolation polynomials on [-1,1]2, as well as new results on [-1,1]3. In particular, compact formulas for the fundamental interpo-lation polynomials are derived, based on n3/4 + (n2) nodes of a cubature formula on [-1,1]3.

  7. CLOSED SMOOTH SURFACE DEFINED FROM CUBIC TRIANGULAR SPLINES

    Institute of Scientific and Technical Information of China (English)

    Ren-zhong Feng; Ren-hong Wang

    2005-01-01

    In order to construct closed surfaces with continuous unit normal, we introduce a new spline space on an arbitrary closed mesh of three-sided faces. Our approach generalizes an idea of Goodman and is based on the concept of 'Geometric continuity' for piecewise polynomial parametrizations. The functions in the spline space restricted to the faces are cubic triangular polynomials. A basis of the spline space is constructed of positive functions which sum to 1. It is also shown that the space is suitable for interpolating data at the midpoints of the faces.

  8. Exotic Universal Solutions in Cubic Superstring Field Theory

    CERN Document Server

    Erler, Theodore

    2010-01-01

    We present a class of analytic solutions of cubic superstring field theory in the universal sector on a non-BPS D-brane. Computation of the action and gauge invariant overlap reveal that the solutions carry half the tension of a non-BPS D-brane. However, the solutions do not satisfy the reality condition. In fact, they display an intriguing topological structure: We find evidence that conjugation of the solutions is equivalent to a gauge transformation that cannot be continuously deformed to the identity.

  9. Self-trapping transition in nonlinear cubic lattices

    CERN Document Server

    Naether, Uta; Guzmán-Silva, Diego; Molina, Mario I; Vicencio, Rodrigo A

    2013-01-01

    We explore the fundamental question about the critical nonlinearity value needed to dynamically localize energy in discrete nonlinear cubic (Kerr) lattices. We focus on the effective frequency and participation ratio of the profile to determine the transition into localization, performing several numerical simulations in one-, two-, and three-dimensional lattices. A simple criterium is developed - for the case of an initially localized excitation - defining the transition region in parameter space ("dynamical tongue") from a delocalized to a localized profile. A general analytical estimate of the critical nonlinearity value for which this transition occurs is obtained.

  10. Cubic versus spherical magnetic nanoparticles: the role of surface anisotropy.

    Science.gov (United States)

    Salazar-Alvarez, G; Qin, J; Sepelák, V; Bergmann, I; Vasilakaki, M; Trohidou, K N; Ardisson, J D; Macedo, W A A; Mikhaylova, M; Muhammed, M; Baró, M D; Nogués, J

    2008-10-08

    The magnetic properties of maghemite (gamma-Fe2O3) cubic and spherical nanoparticles of similar sizes have been experimentally and theoretically studied. The blocking temperature, T(B), of the nanoparticles depends on their shape, with the spherical ones exhibiting larger T(B). Other low temperature properties such as saturation magnetization, coercivity, loop shift or spin canting are rather similar. The experimental effective anisotropy and the Monte Carlo simulations indicate that the different random surface anisotropy of the two morphologies combined with the low magnetocrystalline anisotropy of gamma-Fe2O3 is the origin of these effects.

  11. Configuration spaces of an embedding torus and cubical spaces

    OpenAIRE

    Jourdan, Jean-Philippe

    2006-01-01

    For a smooth manifold M obtained as an embedding torus, A U Cx[-1,1], we consider the ordered configuration space F_k(M) of k distinct points in M. We show that there is a homotopical cubical resolution of F_k(M) defined from the configuration spaces of A and C. From it, we deduce a universal method for the computation of the pure braid groups of a manifold. We illustrate the method in the case of the Mobius band.

  12. Ionic Conduction in Cubic Zirconias at Low Temperatures

    Institute of Scientific and Technical Information of China (English)

    Ying LI; Yunfa CHEN; Jianghong GONG

    2004-01-01

    The ac conductivities of Y2O3 or CaO-stabilized cubic zirconias were obtained from complex impedance measurements in the temperature range from 373 to 473 K. By analyzing the temperature-dependence of the resultant dc conductivities, it was shown that the activation energies for conduction are lower than those reported previously for the same materials at high temperatures. Comparing the activation energy data with the theoretically estimated values revealed that there may exist a certain, although very small, amount of free oxygen vacancies in the test samples at low temperatures and the conduction in the test samples is a result of the migration of these free oxygen vacancies.

  13. Cubic to tetragonal crystal lattice reconstruction during ordering or decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Byung-kl [Carnegie-Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering

    1992-09-01

    This thesis studied thermodynamic stability and morphology of product phases in diffusional phase transformations involving cubic-to-tetragonal crystal lattice reconstructions. Two different kinds of diffusional transformations were examined: L1{sub 0} ordering (fcc to fct lattice change) and decomposition of off-stoichiometric B2 ordering alloys accompanying bcc to fcc Bain transformation. In the first case, Fe-45 at.% Pd alloys were studied by TEM; in the second, the Bain strain relaxation during decomposition of hyper-eutectoid Cu-9.04 wt% Be alloy was studied. CuAu and InMg were also studied.

  14. On the {P2, P3}-Factor of Cubic Graphs

    Institute of Scientific and Technical Information of China (English)

    GOU Kui-xiang; SUN Liang

    2005-01-01

    Let G = ( V, E) be a finite simple graph and Pn denote the path of order n. A spanning subgraph F is called a {P2, P3}-factor of G if each component of F is isomorphic to P2 or P3. With the path-covering method, it is proved that any connected cubic graph with at least 5 vertices has a { P2, P3 }-factor F such that | P3 (F) |≥|P2 (F) |, where P2 (F) and P3 (F) denote the set of components of P2 and P3 in F,respectively.

  15. Inhomogeneous atomic Bose-Fermi mixtures in cubic lattices.

    Science.gov (United States)

    Cramer, M; Eisert, J; Illuminati, F

    2004-11-05

    We determine the ground state properties of inhomogeneous mixtures of bosons and fermions in cubic lattices and parabolic confining potentials. For finite hopping we determine the domain boundaries between Mott-insulator plateaux and hopping-dominated regions for lattices of arbitrary dimension within mean-field and perturbation theory. The results are compared with a new numerical method that is based on a Gutzwiller variational approach for the bosons and an exact treatment for the fermions. The findings can be applied as a guideline for future experiments with trapped atomic Bose-Fermi mixtures in optical lattices.

  16. Compressibility and thermal expansion of cubic silicon nitride

    DEFF Research Database (Denmark)

    Jiang, Jianzhong; Lindelov, H.; Gerward, Leif

    2002-01-01

    The compressibility and thermal expansion of the cubic silicon nitride (c-Si3N4) phase have been investigated by performing in situ x-ray powder-diffraction measurements using synchrotron radiation, complemented with computer simulations by means of first-principles calculations. The bulk...... compressibility of the c-Si3N4 phase originates from the average of both Si-N tetrahedral and octahedral compressibilities where the octahedral polyhedra are less compressible than the tetrahedral ones. The origin of the unit cell expansion is revealed to be due to the increase of the octahedral Si-N and N-N bond...

  17. Theoretical and Experimental Study of Time Reversal in Cubic Crystals

    Institute of Scientific and Technical Information of China (English)

    陆铭慧; 张碧星; 汪承灏

    2004-01-01

    The self-adaptive focusing of the time reversal in anisotropic media is studied theoretically and experimentally. It is conducted for the compressional wave field in the cubic crystal silicon. The experimental result is in agreement with our theoretical analysis. The focusing gain and the displacement distributions of the time reversal field are analysed in detail. It is shown that the waves from different elements of the transducer array arrive at the original place of the source simultaneously after the time reversal operation. The waveform distortions caused by the velocity anisotropy can automatically be compensated for after the time reversal processing.

  18. Rotary Ultrasonic Machining of Poly-Crystalline Cubic Boron Nitride

    Directory of Open Access Journals (Sweden)

    Kuruc Marcel

    2014-12-01

    Full Text Available Poly-crystalline cubic boron nitride (PCBN is one of the hardest material. Generally, so hard materials could not be machined by conventional machining methods. Therefore, for this purpose, advanced machining methods have been designed. Rotary ultrasonic machining (RUM is included among them. RUM is based on abrasive removing mechanism of ultrasonic vibrating diamond particles, which are bonded on active part of rotating tool. It is suitable especially for machining hard and brittle materials (such as glass and ceramics. This contribution investigates this advanced machining method during machining of PCBN.

  19. Cubic Plus Association Equation of State for Flow Assurance Projects

    DEFF Research Database (Denmark)

    dos Santos, Leticia Cotia; Abunahman, Samir Silva; Tavares, Frederico Wanderley

    2015-01-01

    Thermodynamic hydrate inhibitors such as methanol, ethanol, (mono) ethylene glycol (MEG), and triethylene glycol (TEG) are widely used in the oil and gas industry. On modeling these compounds, we show here how the CPA equation of state was implemented in an in-house process simulator as an in......-built model: To validate the implementation, we show calulations for binary systems containing hydrate inhibitors and water or hydrocarbons using the Cubic Plus Association (CPA) and Soave-Redlich-Kwong (SRK) equation of states, also comparing against experimental data. For streams containing natural gas...

  20. Elasticity tensor and ultrasonic velocities for anisotropic cubic polycrystal

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The orientation distribution of crystallites in a polycrystal can be described by the orientation distribution function(ODF) . The ODF can be expanded under the Wigner D-bases. The expanded coefficients in the ODF are called the texture coefficients. In this paper,we use the Clebsch-Gordan expression to derive an explicit expression of the elasticity tensor for an anisotropic cubic polycrystal. The elasticity tensor contains three material constants and nine texture coefficients. In order to measure the nine texture coefficients by ultrasonic wave,we give relations between the nine texture coefficients and ultrasonic propagation velocities. We also give a numerical example to check the relations.

  1. Tensor tomography of stresses in cubic single crystals

    Directory of Open Access Journals (Sweden)

    Dmitry D. Karov

    2015-03-01

    Full Text Available The possibility of optical tomography applying to investigation of a two-dimensional and a three-dimensional stressed state in single cubic crystals has been studied. Stresses are determined within the framework of the Maxwell piezo-optic law (linear dependence of the permittivity tensor on stresses and weak optical anisotropy. It is shown that a complete reconstruction of stresses in a sample is impossible both by translucence it in the parallel planes system and by using of the elasticity theory equations. For overcoming these difficulties, it is offered to use a method of magnetophotoelasticity.

  2. Effect of rapid thermal annealing on polycrystalline InGaN thin films deposited on fused silica substrates

    Energy Technology Data Exchange (ETDEWEB)

    Kazazis, S.A., E-mail: kazazis@physics.uoc.gr [Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Papadomanolaki, E. [Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Androulidaki, M.; Tsagaraki, K.; Kostopoulos, A.; Aperathitis, E. [Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion (Greece); Iliopoulos, E. [Department of Physics, University of Crete, P.O. Box 2208, 71003 Heraklion (Greece); Microelectronics Research Group, IESL-FORTH, P.O. Box 1385, 71110 Heraklion (Greece)

    2016-07-29

    In this work, we report on the effects of Rapid Thermal Annealing (RTA) on the structural, electrical and optical properties of polycrystalline InGaN thin films deposited on amorphous fused silica substrates by molecular beam deposition. Films with 20%, 35% and 50% indium content were grown and subjected to post-deposition RTA treatments. Annealing promoted crystallization in the case of the film with 0.5 InN mole fraction while in the lower indium content cases no apparent effect on the improvement of crystallinity was observed. For RTA temperature above 550 °C, film resistivity was reduced by at least two orders of magnitude due to annealing-induced increased carrier concentration. The optical properties of the films were systematically studied by variable angle spectroscopic ellipsometry. In the highest indium content films, a monotonic optical band gap widening was observed upon annealing, explained by the Burstein–Moss effect. In contrast, photoluminescence peak position was not affected by the resulting Fermi level changes. This is attributed to the different mechanisms between optical absorption and emission in such highly doped semiconductors. - Highlights: • Polycrystalline InGaN films were deposited on fused silica substrates. • Rapid thermal annealing effect on structural, electrical and optical properties studied. • Films' resistivity significantly reduced after annealing at 550 °C, in all InN content cases. • In higher indium content films, optical band gap blueshifts upon annealing, due to Burstein–Moss effect. • Photoluminescence emission position was unaffected by the band gap shift.

  3. Metallo-Organic Solution Deposition of Ferroelectric PZT Films

    Science.gov (United States)

    1992-09-09

    perovskite structure was reduced by the presence of a cubic pyrochiore-like phase related to Pb 2Ti20 6 [24]. The films consolidated at 300 and 400"C are...coherent imaging, solar cell physics, battery electrochemistry, battery testing and evaluation. Mechanics and Materials Technology Center: Evaluation...films. For example, lead al- koxide and dtanium alkoxide compounds can be hydrolyzed to form hydroxide-alkoidde com- pounds: Pb (OR)2 + H20--* Pb (OR

  4. Deposition of copper selenide thin films and nanoparticles

    Science.gov (United States)

    Hu, Yunxiang; Afzaal, Mohammad; Malik, Mohammad A.; O'Brien, Paul

    2006-12-01

    A new method is reported for the growth of copper selenide thin films and nanoparticles using copper acetylacetonate and trioctylphosphine selenide. Aerosol-assisted chemical vapor deposition experiments lead to successful deposition of tetragonal Cu 2Se films. In contrast, hexadecylamine capped nanoparticles are composed of cubic Cu 2-xSe. The deposited materials are optically and structurally characterized. The results of this comprehensive study are described and discussed.

  5. Film Implementation of a Neutron Detector (FIND): Critical Materials Properties

    Science.gov (United States)

    2007-09-01

    the BN film (~ 2.3), and is the wavelength of the light. Note that n < nSi ( nSi ≈ 3.9 for blue light), and so no phase shift exists at the film...Properties of Cubic Boron Nitride,” ILIR’00: SSC San Diego In-House Laboratory Independent Research 2000 Annual Report, SSC San Diego TD 3115 (May), pp

  6. Roll-to-roll slot-die coating of 400 mm wide, flexible, transparent Ag nanowire films for flexible touch screen panels

    OpenAIRE

    Dong-Ju Kim; Hae-In Shin; Eun-Hye Ko; Ki-Hyun Kim; Tae-Woong Kim; Han-Ki Kim

    2016-01-01

    We report fabrication of large area Ag nanowire (NW) film coated using a continuous roll-to-roll (RTR) slot die coater as a viable alternative to conventional ITO electrodes for cost-effective and large-area flexible touch screen panels (TSPs). By controlling the flow rate of shear-thinning Ag NW ink in the slot die, we fabricated Ag NW percolating network films with different sheet resistances (30?70?Ohm/square), optical transmittance values (89?90%), and haze (0.5?1%) percentages. Outer/inn...

  7. SpaceInn hare-and-hounds exercise: Estimation of stellar properties using space-based asteroseismic data

    Science.gov (United States)

    Reese, D. R.; Chaplin, W. J.; Davies, G. R.; Miglio, A.; Antia, H. M.; Ball, W. H.; Basu, S.; Buldgen, G.; Christensen-Dalsgaard, J.; Coelho, H. R.; Hekker, S.; Houdek, G.; Lebreton, Y.; Mazumdar, A.; Metcalfe, T. S.; Silva Aguirre, V.; Stello, D.; Verma, K.

    2016-07-01

    Context. Detailed oscillation spectra comprising individual frequencies for numerous solar-type stars and red giants are either currently available, e.g. courtesy of the CoRoT, Kepler, and K2 missions, or will become available with the upcoming NASA TESS and ESA PLATO 2.0 missions. The data can lead to a precise characterisation of these stars thereby improving our understanding of stellar evolution, exoplanetary systems, and the history of our galaxy. Aims: Our goal is to test and compare different methods for obtaining stellar properties from oscillation frequencies and spectroscopic constraints. Specifically, we would like to evaluate the accuracy of the results and reliability of the associated error bars, and to see where there is room for improvement. Methods: In the context of the SpaceInn network, we carried out a hare-and-hounds exercise in which one group, the hares, simulated observations of oscillation spectra for a set of ten artificial solar-type stars, and a number of hounds applied various methods for characterising these stars based on the data produced by the hares. Most of the hounds fell into two main groups. The first group used forward modelling (i.e. applied various search/optimisation algorithms in a stellar parameter space) whereas the second group relied on acoustic glitch signatures. Results: Results based on the forward modelling approach were accurate to 1.5% (radius), 3.9% (mass), 23% (age), 1.5% (surface gravity), and 1.8% (mean density), as based on the root mean square difference. Individual hounds reached different degrees of accuracy, some of which were substantially better than the above average values. For the two 1M⊙ stellar targets, the accuracy on the age is better than 10% thereby satisfying the requirements for the PLATO 2.0 mission. High stellar masses and atomic diffusion (which in our models does not include the effects of radiative accelerations) proved to be sources of difficulty. The average accuracies for the

  8. Effect of Annealing on Structural and Optical Properties of Cu Doped In2O3 Thin Films

    OpenAIRE

    S. Kaleemulla; N. Madhusudhana Rao; N. Sai Krishna; M. Kuppan; M. Rigana Begam; M. Shobana

    2014-01-01

    Cu-doped In2O3 thin films were prepared using flash evaporation method at different Cu-doping levels. The effect of annealing was studied on the structure, morphology and optical properties of the thin films. The films exhibited cubic structure and optical transmittance of the films increasing with annealing temperature. The highest optical transmittance of 78 % was observed with band gap of 4.09 eV.

  9. Interplay between surface and surface resonance states on height selective stability of fcc Dy(111) film at nanoscale.

    Science.gov (United States)

    Liu, Xiaojie; Wang, Cai-Zhuang; Hupalo, Myron; Ho, Kai-Ming; Thiel, Patricia A; Tringides, Michael C

    2016-11-16

    Using first-principles calculations we show that face-centered cubic Dy(111) ultrathin films exhibit height selective stability. The origin of such height selection can be attributed to the interplay between the localized surface states and surface resonance states due to electron confinement effects. Such effect could be utilized to manipulate the film thickness at the atomic level to achieve desirable film properties or to control the growth of nanostructures on the thin film for various applications.

  10. Polyimide Aerogel Thin Films

    Science.gov (United States)

    Meador, Mary Ann; Guo, Haiquan

    2012-01-01

    Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

  11. Cubic optical elements for an accommodative intraocular lens.

    Science.gov (United States)

    Simonov, Aleksey N; Vdovin, Gleb; Rombach, Michiel C

    2006-08-21

    We present a new accommodative intraocular lens based on a two-element varifocal Alvarez lens. The intraocular lens consists of (1) an anterior element combining a spherical lens for refractive power with a cubic surface for the varifocal effect, and (2) a posterior element with a cubic surface only. The focal length of the IOL lens changes when the superimposed refractive elements shift in opposite directions in a plane perpendicular to the optical axis. The ciliary muscle will drive the accommodation by a natural process of contraction and relaxation. Results of ray-tracing simulations of the model eye with the two-element intraocular lens are presented for on-axis and off-axis vision. The configuration of the lens is optimized to reduce refractive errors as well as effects of misalignment. A prototype with a clear aperture of ~5.7 mm is manufactured and evaluated in air with a Shack-Hartmann wave-front sensor. It provides an accommodation range of ~4 dioptres in the eye at a ~0.75-mm lateral displacement of the optical elements. The experimentally measured on-axis optical performance of the IOL lens agrees with the theoretically predicted performance.

  12. Nonlinear structure formation in the Cubic Galileon gravity model

    CERN Document Server

    Barreira, Alexandre; Hellwing, Wojciech A; Baugh, Carlton M; Pascoli, Silvia

    2013-01-01

    We model the linear and nonlinear growth of large scale structure in the Cubic Galileon gravity model, by running a suite of N-body cosmological simulations using the {\\tt ECOSMOG} code. Our simulations include the Vainshtein screening effect, which reconciles the Cubic Galileon model with local tests of gravity. In the linear regime, the amplitude of the matter power spectrum increases by $\\sim 25%$ with respect to the standard $\\Lambda$CDM model today. The modified expansion rate accounts for $\\sim 20%$ of this enhancement, while the fifth force is responsible for only $\\sim 5%$. This is because the effective unscreened gravitational strength deviates from standard gravity only at late times, even though it can be twice as large today. In the nonlinear regime ($k \\gtrsim 0.1 h\\rm{Mpc}^{-1}$), the fifth force leads to only a modest increase ($\\lesssim 8%$) in the clustering power on all scales due to the very efficient operation of the Vainshtein mechanism. Such a strong effect is typically not seen in other...

  13. A family of quasi-cubic blended splines and applications

    Institute of Scientific and Technical Information of China (English)

    SU Ben-yue; TAN Jie-qing

    2006-01-01

    A class of quasi-cubic B-spline base functions by trigonometric polynomials are established which inherit properties similar to those of cubic B-spline bases. The corresponding curves with a shape parameter α, defined by the introduced base functions, include the B-spline curves and can approximate the B-spline curves from both sides. The curves can be adjusted easily by using the shape parameter α, where dpi(α,t) is linear with respect to dα for the fixed t. With the shape parameter chosen properly,the defined curves can be used to precisely represent straight line segments, parabola segments, circular arcs and some transcendental curves, and the corresponding tensor product surfaces can also represent spherical surfaces, cylindrical surfaces and some transcendental surfaces exactly. By abandoning positive property, this paper proposes a new C2 continuous blended interpolation spline based on piecewise trigonometric polynomials associated with a sequence of local parameters. Illustration showed that the curves and surfaces constructed by the blended spline can be adjusted easily and freely. The blended interpolation spline curves can be shape-preserving with proper local parameters since these local parameters can be considered to be the magnification ratio to the length of tangent vectors at the interpolating points. The idea is extended to produce blended spline surfaces.

  14. Partially Blended Constrained Rational Cubic Trigonometric Fractal Interpolation Surfaces

    Science.gov (United States)

    Chand, A. K. B.; Tyada, K. R.

    2016-08-01

    Fractal interpolation is an advance technique for visualization of scientific shaped data. In this paper, we present a new family of partially blended rational cubic trigonometric fractal interpolation surfaces (RCTFISs) with a combination of blending functions and univariate rational trigonometric fractal interpolation functions (FIFs) along the grid lines of the interpolation domain. The developed FIFs use rational trigonometric functions pi,j(θ) qi,j(θ), where pi,j(θ) and qi,j(θ) are cubic trigonometric polynomials with four shape parameters. The convergence analysis of partially blended RCTFIS with the original surface data generating function is discussed. We derive sufficient data-dependent conditions on the scaling factors and shape parameters such that the fractal grid line functions lie above the grid lines of a plane Π, and consequently the proposed partially blended RCTFIS lies above the plane Π. Positivity preserving partially blended RCTFIS is a special case of the constrained partially blended RCTFIS. Numerical examples are provided to support the proposed theoretical results.

  15. Observation of Body-Centered Cubic Gold Nanocluster.

    Science.gov (United States)

    Liu, Chao; Li, Tao; Li, Gao; Nobusada, Katsuyuki; Zeng, Chenjie; Pang, Guangsheng; Rosi, Nathaniel L; Jin, Rongchao

    2015-08-17

    The structure of nanoparticles plays a critical role in dictating their material properties. Gold is well known to adopt face-centered cubic (fcc) structure. Herein we report the first observation of a body-centered cubic (bcc) gold nanocluster composed of 38 gold atoms protected by 20 adamantanethiolate ligands and two sulfido atoms ([Au38S2(SR)20], where R=C10H15) as revealed by single-crystal X-ray crystallography. This bcc structure is in striking contrast with the fcc structure of bulk gold and conventional Au nanoparticles, as well as the bi-icosahedral structure of [Au38(SCH2CH2Ph)24]. The bcc nanocluster has a distinct HOMO-LUMO gap of ca. 1.5 eV, much larger than the gap (0.9 eV) of the bi-icosahedral [Au38(SCH2CH2Ph)24]. The unique structure of the bcc gold nanocluster may be promising in catalytic applications.

  16. Four-dimensional black holes in Einsteinian cubic gravity

    Science.gov (United States)

    Bueno, Pablo; Cano, Pablo A.

    2016-12-01

    We construct static and spherically symmetric generalizations of the Schwarzschild- and Reissner-Nordström-(anti-)de Sitter [RN-(A)dS] black-hole solutions in four-dimensional Einsteinian cubic gravity (ECG). The solutions are characterized by a single function which satisfies a nonlinear second-order differential equation. Interestingly, we are able to compute independently the Hawking temperature T , the Wald entropy S and the Abbott-Deser mass M of the solutions analytically as functions of the horizon radius and the ECG coupling constant λ . Using these we show that the first law of black-hole mechanics is exactly satisfied. Some of the solutions have positive specific heat, which makes them thermodynamically stable, even in the uncharged and asymptotically flat case. Further, we claim that, up to cubic order in curvature, ECG is the most general four-dimensional theory of gravity which allows for nontrivial generalizations of Schwarzschild- and RN-(A)dS characterized by a single function which reduce to the usual Einstein gravity solutions when the corresponding higher-order couplings are set to zero.

  17. Novel Cubic Magnetite Nanoparticle Synthesis Using Room Temperature Ionic Liquid

    Directory of Open Access Journals (Sweden)

    M. Sundrarajan

    2012-01-01

    Full Text Available Room Temperature Ionic liquids are relatively more useful in the synthesis of inorganic nanostructured materials because of their unique properties. To synthesize the iron oxide nanoparticle in simple precipitation method, a novel ionic liquid was used as the greener medium and stabilizing agent namely “1-n-butyl-3-methylimidazolium trifluoromethane sulfonate [BMIM][TfO]”. The crystallinity, chemical structure, morphology and magnetic properties of the synthesized magnetite nanoparticles have been characterized by using X-ray diffraction (XRD, Fourier Transform Infrared (FT-IR, Scanning electron microscopy (SEM, Atomic force microscopy(AFM, Transmission electron microscopy (TEM and Vibrating sample magnetometer (VSM studies. The XRD study is divulge that the synthesized magnetite nanoparticles have inverse spinel face centered cubic structure. The FT-IR vibration peaks show the formation of Fe3O4 nanoparticles, where the vibration peak for Fe-O is deliberately presence at 584 cm-1. The average particle size of the synthesized nanoparticles is found to be 35 nm. Homogeneously dispersed cubic shape with superstructure is found through SEM, AFM and TEM examination studies. The synthesized iron oxide nanoparticles have a high saturation magnetization value of 25 emu/g, which is very much useful for biomedical applications.

  18. XPS analysis for cubic boron nitride crystal synthesized under high pressure and high temperature using Li{sub 3}N as catalysis

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Xiaofei [School of Materials Science and Engineering, Shandong Jianzhu University, Ji’nan 250101 (China); School of Materials Science and Engineering, Shandong University, Ji’nan 250061 (China); Xu, Bin, E-mail: xubin@sdjzu.edu.cn [School of Materials Science and Engineering, Shandong Jianzhu University, Ji’nan 250101 (China); Zhang, Wen [School of Materials Science and Engineering, Shandong Jianzhu University, Ji’nan 250101 (China); Cai, Zhichao [School of Materials Science and Engineering, Shandong University, Ji’nan 250061 (China); Wen, Zhenxing [School of Materials Science and Engineering, Shandong Jianzhu University, Ji’nan 250101 (China)

    2014-12-01

    Highlights: • The cBN was synthesized by Li{sub 3}N as catalyst under high pressure and high temperature (HPHT). • The film coated on the as-grown cBN crystals was studied by XPS. • The electronic structure variation in the film was investigated. • The growth mechanism of cubic boron nitride crystal was analyzed briefly. - Abstract: Cubic boron nitride (cBN) single crystals are synthesized with lithium nitride (Li3N) as catalyst under high pressure and high temperature. The variation of electronic structures from boron nitride of different layers in coating film on the cBN single crystal has been investigated by X-ray photoelectron spectroscopy. Combining the atomic concentration analysis, it was shown that from the film/cBN crystal interface to the inner, the sp{sup 2} fractions are decreasing, and the sp{sup 3} fractions are increasing in the film at the same time. Moreover, by transmission electron microscopy, a lot of cBN microparticles are found in the interface. For there is no Li{sub 3}N in the film, it is possible that Li{sub 3}N first reacts with hexagonal boron nitride to produce Li{sub 3}BN{sub 2} during cBN crystals synthesis under high pressure and high temperature (HPHT). Boron and nitrogen atoms, required for cBN crystals growth, could come from the direct conversion from hexagonal boron nitride with the catalysis of Li{sub 3}BN{sub 2} under high pressure and high temperature, but not directly from the decomposition of Li{sub 3}BN{sub 2}.

  19. Keighren, Innes M., Charles W.J. Withers, Bill Bell. Travels into Print: Exploration, Writing, and publishing with John Murray, 1773-1859 (Chicago and London: The University of Chicago Press, 2015

    Directory of Open Access Journals (Sweden)

    Jasper Schelstraete

    2016-06-01

    Full Text Available A review of Innes M. Keighren, Charles W.J. Withers, Bill Bell's Travels into Print: Exploration, Writing, and publishing with John Murray, 1773-1859. Chicago and London: The University of Chicago Press, 2015. 392 pp. $45.

  20. Non-spherical micelles in an oil-in-water cubic phase

    DEFF Research Database (Denmark)

    Leaver, M.; Rajagopalan, V.; Ulf, O.

    2000-01-01

    The cubic phase formed between the microemulsion and hexagonal phases of the ternary pentaethylene glycol dodecyl ether (C12E5)-decane-water system and that doped with small amounts of sodium dodecylsulfate (SDS) have been investigated. The presence of discrete oil-swollen micelles in the cubic...... phase, both with and without SDS, was established by NMR self-diffusion. In addition H-2 NMR relaxation experiments have demonstrated that the micelles in the cubic phase are non-spherical, having grown and changed shape upon formation of the cubic phase from the micellar solution. Small angle...... scattering experiments indicate that the lattice parameter for the cubic phase is inconsistent with a simple packing of micelles. Whilst insufficient reflections were observed to establish the space group of the cubic phase uniquely, those that were are consistent with two commonly observed space groups...

  1. Self-assembled flower-like nanostructures of InN and GaN grown by plasma-assisted molecular beam epitaxy

    Indian Academy of Sciences (India)

    Mahesh Kumar; T N Bhat; M K Rajpalke; B Roul; P Misra; L M Kukreja; Neeraj Sinha; A T Kalghatgi; S B Krupanidhi

    2010-06-01

    Nanosized hexagonal InN flower-like structures were fabricated by droplet epitaxy on GaN/Si(111) and GaN flower-like nanostructure fabricated directly on Si(111) substrate using radio frequency plasma-assisted molecular beam epitaxy. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to study the crystallinity and morphology of the nanostructures. Moreover, X-ray photoelectron spectroscopy (XPS) and photoluminescence (PL) were used to investigate the chemical compositions and optical properties of nano-flowers, respectively. Activation energy of free exciton transitions in GaN nano-flowers was derived to be ∼ 28.5 meV from the temperature dependent PL studies. The formation process of nanoflowers is investigated and a qualitative mechanism is proposed.

  2. Characterization of the InN conversion layer in InP surface by ammonia gas: Nuclear reaction analysis, X-ray diffraction and Raman scattering studies

    Energy Technology Data Exchange (ETDEWEB)

    Mizuki, Y. [College of Engineering and Research Center of Ion Beam Technology, Hosei University, Koganei, Tokyo 184-8584 (Japan); Onoue, A. [College of Engineering and Research Center of Ion Beam Technology, Hosei University, Koganei, Tokyo 184-8584 (Japan); Kuriyama, K. [College of Engineering and Research Center of Ion Beam Technology, Hosei University, Koganei, Tokyo 184-8584 (Japan)]. E-mail: kuri@ionbeam.hosei.ac.jp; Hasegawa, M. [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan); Sakamoto, I. [National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568 (Japan)

    2006-08-15

    The surface layer of InP(1 0 0) wafer is converted into {alpha}-InN phase (wurtzite) by annealing it at around 510 {sup o}C for 5 h under NH{sub 3} gas flow. X-ray diffraction analysis shows that the conversion layer is a (1 1 -2 0) oriented InN. This result is also supported by E{sub 1}(TO) and A{sub 1}(LO) phonon modes observed by a Raman scattering method, originated from the (1 1 -2 0) face of {alpha}-InN. The converted layer evaluated by nuclear reaction analysis using a {sup 14}N(d, p){sup 15}N reaction includes a N concentration of {approx}6 x 10{sup 22} cm{sup -3}.

  3. Annual Review of BPA-Funded Projects in Natural and Artificial Propagation of Salmonids, March 27-29, 1985, Holiday Inn Airport, Portland, Oregon.

    Energy Technology Data Exchange (ETDEWEB)

    United States. Bonneville Power Administration.

    1985-04-01

    The Fish and Wildlife Division of Bonneville Power Administration (BPA) hosted a meeting for contractors to present the results of fiscal year 1984 research conducted to implement the Northwest Power Planning Council's Fish and Wildlife Program. The meeting focused on those projects specifically related to natural and artificial propagation of salmonids. The presentations were held at the Holiday Inn Airport in Portland, Oregon, on March 27-29, 1985. This document contains abstracts of the presentations from that meeting. Section 1 contains abstracts on artificial propagation, fish health, and downstream migration, and Section 2 contains abstracts on natural propagation and habitat improvement. The abstracts are indexed by BPA Project Number and by Fish and Wildlife Program Measure. The registered attendees at the meeting are listed alphabetically in Appendix A and by affiliation in Appendix B.

  4. On the Development Problems & Countermeasures of the Boutique Family Inn in the Phoenix Ancient Town%凤凰古城精品家庭宾馆发展问题及对策研究

    Institute of Scientific and Technical Information of China (English)

    袁敏

    2014-01-01

    文章对精品家庭宾馆的内涵进行了分析,精品家庭宾馆的“精”集细、独、特于一身。对凤凰古城精品家庭宾馆发展问题从感官层面、服务层面、体验层面和经营层面四个层面予以解读。解决精品家庭宾馆发展问题的根源在于提升店主本身文化素质及酒店管理水平,在此基础上提出相应解决措施。旨在为凤凰古城精品家庭宾馆的理论创新和实践运营提供指导,促进我国精品家庭宾馆的发展。%The author of this paper analyses the connotation of the Boutique Family Inn .The characteristics of boutique family inn are detailed ,unique and outstanding .The development problems of the Phoenix ancient town boutique family inn can be analyzed from four aspects as follows : sensory level , service level , experience level and management level .To solve the problem is to develop the culture quality &the hotel management level of the owner and then put forward the corresponding solving measures , promote innovation and the practice operation for the Phoenix Family Inn so as to promote the development of China's boutique family inn .

  5. Nanoindentation and Adhesion Properties of Ta Thin Films

    Directory of Open Access Journals (Sweden)

    Yuan-Tsung Chen

    2013-01-01

    Full Text Available Ta films were sputtered onto a glass substrate with thicknesses from 500 Å to 1500 Å under the following conditions: (a as-deposited films were maintained at room temperature (RT, (b films were postannealed at TA=150°C for 1 h, and (c films were postannealed at TA=250°C for 1 h. X-ray diffraction (XRD results revealed that the Ta films had a body-centered cubic (BCC structure. Postannealing conditions and thicker Ta films exhibited a stronger Ta (110 crystallization than as-deposited and thinner films. The nanoindention results revealed that Ta thin films are sensitive to mean grain size, including a valuable hardness (H and Young’s modulus (E. High nanomechanical properties of as-deposited and thinner films can be investigated by grain refinement, which is consistent with the Hall-Petch effect. The surface energy of as-deposited Ta films was higher than that in postannealing treatments. The adhesion of as-deposited Ta films was stronger than postannealing treatments because of crystalline degree effect. The maximal H and E and the optimal adhesion of an as-deposited 500-Å-thick Ta film were 15.6 GPa, 180 GPa, and 51.56 mJ/mm2, respectively, suggesting that a 500-Å-thick Ta thin film can be used in seed and protective layer applications.

  6. Analytical Approximate Solutions for the Cubic-Quintic Duffing Oscillator in Terms of Elementary Functions

    OpenAIRE

    A. Beléndez; ALVAREZ, M. L.; Francés, J.; S. Bleda; Beléndez, T.; Nájera, A.; Arribas, E.

    2012-01-01

    Accurate approximate closed-form solutions for the cubic-quintic Duffing oscillator are obtained in terms of elementary functions. To do this, we use the previous results obtained using a cubication method in which the restoring force is expanded in Chebyshev polynomials and the original nonlinear differential equation is approximated by a cubic Duffing equation. Explicit approximate solutions are then expressed as a function of the complete elliptic integral of the first kind and the Jacobi ...

  7. Quantum-Carnot engine for particle confined to cubic potential

    Science.gov (United States)

    Sutantyo, Trengginas Eka P.; Belfaqih, Idrus H.; Prayitno, T. B.

    2015-09-01

    Carnot cycle consists of isothermal and adiabatic processes which are reversible. Using analogy in quantum mechanics, these processes can be well explained by replacing variables in classical process with a quantum system. Quantum system which is shown in this paper is a particle that moves under the influence of a cubic potential which is restricted only to the state of the two energy levels. At the end, the efficiency of the system is shown as a function of the width ratio between the initial conditions and the farthest wall while expanding. Furthermore, the system efficiency will be considered 1D and 2D cases. The providing efficiencies are different due to the influence of the degeneration of energy and the degrees of freedom of the system.

  8. Gauge Fixing of Modified Cubic Open Superstring Field Theory

    CERN Document Server

    Kohriki, Maiko; Kunitomo, Hiroshi

    2011-01-01

    The gauge-fixing problem of modified cubic open superstring field theory is discussed in detail both for the Ramond and Neveu-Schwarz sectors in the Batalin-Vilkovisky (BV) framework. We prove for the first time that the same form of action as the classical gauge-invariant one with the ghost-number constraint on the string field relaxed gives the master action satisfying the BV master equation. This is achieved by identifying independent component fields based on the analysis of the kernel structure of the inverse picture changing operator. The explicit gauge-fixing conditions for the component fields are discussed. In a kind of $b_0=0$ gauge, we explicitly obtain the NS propagator which has poles at the zeros of the Virasoro operator $L_0$.

  9. Quantum-Carnot engine for particle confined to cubic potential

    Energy Technology Data Exchange (ETDEWEB)

    Sutantyo, Trengginas Eka P., E-mail: trengginas.eka@gmail.com; Belfaqih, Idrus H., E-mail: idrushusin21@gmail.com; Prayitno, T. B., E-mail: teguh-budi@unj.ac.id [Department of Physics, State University of Jakarta, Jl. Pemuda No.10, Rawamangun, Jakarta Timur 13220 (Indonesia)

    2015-09-30

    Carnot cycle consists of isothermal and adiabatic processes which are reversible. Using analogy in quantum mechanics, these processes can be well explained by replacing variables in classical process with a quantum system. Quantum system which is shown in this paper is a particle that moves under the influence of a cubic potential which is restricted only to the state of the two energy levels. At the end, the efficiency of the system is shown as a function of the width ratio between the initial conditions and the farthest wall while expanding. Furthermore, the system efficiency will be considered 1D and 2D cases. The providing efficiencies are different due to the influence of the degeneration of energy and the degrees of freedom of the system.

  10. Perbaikan Metode Penghitungan Debit Sungai Menggunakan Cubic Spline Interpolation

    Directory of Open Access Journals (Sweden)

    Budi I. Setiawan

    2007-09-01

    Full Text Available Makalah ini menyajikan perbaikan metode pengukuran debit sungai menggunakan fungsi cubic spline interpolation. Fungi ini digunakan untuk menggambarkan profil sungai secara kontinyu yang terbentuk atas hasil pengukuran jarak dan kedalaman sungai. Dengan metoda baru ini, luas dan perimeter sungai lebih mudah, cepat dan tepat dihitung. Demikian pula, fungsi kebalikannnya (inverse function tersedia menggunakan metode. Newton-Raphson sehingga memudahkan dalam perhitungan luas dan perimeter bila tinggi air sungai diketahui. Metode baru ini dapat langsung menghitung debit sungaimenggunakan formula Manning, dan menghasilkan kurva debit (rating curve. Dalam makalah ini dikemukaan satu canton pengukuran debit sungai Rudeng Aceh. Sungai ini mempunyai lebar sekitar 120 m dan kedalaman 7 m, dan pada saat pengukuran mempunyai debit 41 .3 m3/s, serta kurva debitnya mengikuti formula: Q= 0.1649 x H 2.884 , dimana Q debit (m3/s dan H tinggi air dari dasar sungai (m.

  11. On the undamped vibration absorber with cubic stiffness characteristics

    Science.gov (United States)

    Gatti, G.

    2016-09-01

    In order to improve the performance of a vibration absorber, a nonlinear spring can be used on purpose. This paper presents an analytical insight on the characteristics of an undamped nonlinear vibration absorber when it is attached to a linear spring-mass-damper oscillator. In particular, the nonlinear attachment is modelled as a Duffing's oscillator with a spring characteristics having a linear positive stiffness term plus a cubic stiffness term. The effects of the nonlinearity, mass ratio and frequency ratio are investigated based on an approximate analytical formulation of the amplitude-frequency equation. Comparisons to the linear case are shown in terms of the frequency response curves. The nonlinear absorber seems to show an improved robustness to mistuning respect to the corresponding linear device. However, such a better robustness may be limited by some instability of the expected harmonic response.

  12. Cubic Spline Interpolation Reveals Different Evolutionary Trends of Various Species

    Directory of Open Access Journals (Sweden)

    Li Zhiqiang

    2016-01-01

    Full Text Available Instead of being uniform in each branch of the biological evolutionary tree, the speed of evolution, measured in the number of mutations over a fixed number of years, seems to be much faster or much slower than average in some branches of the evolutionary tree. This paper describes an evolutionary trend discovery algorithm that uses cubic spline interpolation for various branches of the evolutionary tree. As shown in an example, within the vertebrate evolutionary tree, human evolution seems to be currently speeding up while the evolution of chickens is slowing down. The new algorithm can automatically identify those branches and times when something unusual has taken place, aiding data analytics of evolutionary data.

  13. Palladium in cubic silicon carbide: Stability and kinetics

    Science.gov (United States)

    Roma, Guido

    2009-12-01

    Several technological applications of silicon carbide are concerned with the introduction of palladium impurities. Be it intentional or not, this may lead to the formation of silicides. Not only this process is not well understood, but the basic properties of palladium impurities in silicon carbide, such as solubility or diffusion mechanisms, are far from being known. Here the stability and kinetics of isolated Pd impurities in cubic silicon carbide are studied by first principles calculations in the framework of density functional theory. The preferential insertion sites, as well as the main migration mechanisms, are analyzed and presented here, together with the results for solution and migration energies. The early stages of nucleation are discussed based on the properties of isolated impurities and the smallest clusters.

  14. Four-dimensional black holes in Einsteinian cubic gravity

    CERN Document Server

    Bueno, Pablo

    2016-01-01

    We construct static and spherically symmetric generalizations of the Schwarzschild- and Reissner-Nordstr\\"om-(Anti) de Sitter (RN-(A)dS) black-hole solutions in four-dimensional Einsteinian cubic gravity (ECG). The solutions are determined by a single blackening factor which satisfies a non-linear second-order differential equation. Interestingly, we are able to compute independently the Hawking temperature $T$, the Wald entropy $\\mathsf{S}$ and the Abbott-Deser mass $M$ of the solutions analytically as functions of the horizon radius and the ECG coupling constant $\\lambda$. Using these we show that the first law of black-hole mechanics is exactly satisfied. Some of the solutions have positive specific heat, which makes them thermodynamically stable, even in the uncharged and asymptotically flat case.

  15. Structure and energetics of nanotwins in cubic boron nitrides

    Science.gov (United States)

    Zheng, Shijian; Zhang, Ruifeng; Huang, Rong; Taniguchi, Takashi; Ma, Xiuliang; Ikuhara, Yuichi; Beyerlein, Irene J.

    2016-08-01

    Recently, nanotwinned cubic boron nitrides (NT c-BN) have demonstrated extraordinary leaps in hardness. However, an understanding of the underlying mechanisms that enable nanotwins to give orders of magnitude increases in material hardness is still lacking. Here, using transmission electron microscopy, we report that the defect density of twin boundaries depends on nanotwin thickness, becoming defect-free, and hence more stable, as it decreases below 5 nm. Using ab initio density functional theory calculations, we reveal that the Shockley partials, which may dominate plastic deformation in c-BNs, show a high energetic barrier. We also report that the c-BN twin boundary has an asymmetrically charged electronic structure that would resist migration of the twin boundary under stress. These results provide important insight into possible nanotwin hardening mechanisms in c-BN, as well as how to design these nanostructured materials to reach their full potential in hardness and strength.

  16. Linear and cubic dynamic susceptibilities in quantum spin glass

    CERN Document Server

    Busiello, G; Sushkova, V G

    2001-01-01

    The low temperature behaviour of the dynamic nonlinear (cubic) susceptibility chi sub 3 sup ' (omega, T) in quantum d-dimensional Ising spin glass with short-range interactions between spins is investigated in terms of the quantum droplet model and the quantum-mechanical nonlinear response theory is employed. We have revealed a glassy like behaviour of droplet dynamics. The frequency dependence of chi sub 3 sup ' (omega, T) is very remarkable, the temperature dependence is found at very low temperatures (quantum regime). The nonlinear response depends on the tunneling rate for a droplet which regulates the strength of quantum fluctuations. This response has a strong dependence on the distribution of droplet free energies and on the droplet length scale average. Implications for experiments in quantum spin glasses like disordered dipolar quantum Ising magnet LiHo sub x Y sub 1 sub - sub x F sub 4 and pseudospin are noted.

  17. A cubic autocatalytic reaction in a continuous stirred tank reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yakubu, Aisha Aliyu; Yatim, Yazariah Mohd [School of Mathematical Sciences, Universiti Sains Malaysia, 11800 USM, Penang Malaysia (Malaysia)

    2015-10-22

    In the present study, the dynamics of the cubic autocatalytic reaction model in a continuous stirred tank reactor with linear autocatalyst decay is studied. This model describes the behavior of two chemicals (reactant and autocatalyst) flowing into the tank reactor. The behavior of the model is studied analytically and numerically. The steady state solutions are obtained for two cases, i.e. with the presence of an autocatalyst and its absence in the inflow. In the case with an autocatalyst, the model has a stable steady state. While in the case without an autocatalyst, the model exhibits three steady states, where one of the steady state is stable, the second is a saddle point while the last is spiral node. The last steady state losses stability through Hopf bifurcation and the location is determined. The physical interpretations of the results are also presented.

  18. Submicron cubic boron nitride as hard as diamond

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Guoduan; Kou, Zili, E-mail: kouzili@scu.edu.cn, E-mail: yanxz@hpstar.ac.cn; Lei, Li; Peng, Fang; Wang, Qiming; Wang, Kaixue; Wang, Pei; Li, Liang; Li, Yong; Wang, Yonghua [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Yan, Xiaozhi, E-mail: kouzili@scu.edu.cn, E-mail: yanxz@hpstar.ac.cn; Li, Wentao [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai 201203 (China); Bi, Yan [Institute of Fluid Physics and National Key Laboratory of Shockwave and Detonation Physic, China Academy of Engineering Physics, Mianyang 621900 (China); Leng, Yang [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Kowloon, Hong Kong (China); He, Duanwei [Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065 (China); Institute of Fluid Physics and National Key Laboratory of Shockwave and Detonation Physic, China Academy of Engineering Physics, Mianyang 621900 (China)

    2015-03-23

    Here, we report the sintering of aggregated submicron cubic boron nitride (sm-cBN) at a pressure of 8 GPa. The sintered cBN compacts exhibit hardness values comparable to that of single crystal diamond, fracture toughness about 5-fold that of cBN single crystal, in combination with a high oxidization temperature. Thus, another way has been demonstrated to improve the mechanical properties of cBN besides reducing the grain size to nano scale. In contrast to other ultrahard compacts with similar hardness, the sm-cBN aggregates are better placed for potential industrial application, as their relative low pressure manufacturing perhaps be easier and cheaper.

  19. PT-Symmetric Cubic Anharmonic Oscillator as a Physical Model

    CERN Document Server

    Mostafazadeh, A

    2004-01-01

    We perform a perturbative calculation of the physical observables, in particular pseudo-Hermitian position and momentum operators, the equivalent Hermitian Hamiltonian operator, and the classical Hamiltonian for the PT-symmetric cubic anharmonic oscillator, $ H=p^1/(2m)+\\mu^2x^2/2+i\\epsilon x^3 $. Ignoring terms of order $ \\epsilon^4 $ and higher, we show that this system describes an ordinary quartic anharmonic oscillator with a position-dependent mass and real and positive coupling constants. This observation elucidates the classical origin of the reality and positivity of the energy spectrum. We also discuss the quantum-classical correspondence for this PT-symmetric system, compute the associated conserved probability density, and comment on the issue of factor-ordering in the pseudo-Hermitian canonical quantization of the underlying classical system.

  20. Enhanced initial protein adsorption on an engineered nanostructured cubic zirconia

    CERN Document Server

    Sabirianov, R F; Namavar, F

    2010-01-01

    Motivated by experimentally observed biocompatibility enhancement of nanoengineered cubic zirconia ZrO2 coatings to mesenchymal stromal cells, we have carried out computational analysis of the initial immobilization of one of known structural fragment of the adhesive protein (fibronectin) on the corresponding surface. We constructed an atomistic model of the zirconia nano-hillock of 3-fold symmetry based on AFM and TEM images. First-principle quantum-mechanical calculations show a substantial variation of electrostatic potential at the hillock due to the presence of surface features such as edges and vertexes. Using an implemented Monte Carlo simulated annealing method we found the orientation of the immobilized protein on the zirconia surface (both flat and nanostructured) and contribution of the each amino acid residue from the protein sequence to the adsorption energy. Accounting for the variation of the dielectric permittivity at the protein-implant interface we use a model distance-dependent dielectric f...

  1. Inverse cubic law of index fluctuation distribution in Indian markets

    CERN Document Server

    Pan, R K; Pan, Raj Kumar; Sinha, Sitabhra

    2006-01-01

    One of the principal statistical features characterizing the activity in financial markets is the distribution of fluctuations in market indicators such as the index. While the developed stock markets such as the New York Stock Exchange (NYSE) have been found to show heavy-tailed fluctuation distribution, there have been claims that emerging markets behave differently. Here we investigate the distribution of several indices from the Indian financial market, one of the largest emerging markets in the world. We have used both tick-by-tick data from the National Stock Exchange (NSE) and daily closing data from both NSE and Bombay Stock Exchange (BSE). We find that the cumulative distribution of index fluctuations has long tails consistent with a power law having exponent $\\alpha \\approx 3$, independent of the time-scale of observation or the market index used for the analysis. This ``inverse cubic law'' is quantitatively similar to what has been observed in developed markets, thereby providing strong evidence th...

  2. Entanglement across a cubic interface in 3+1 dimensions

    Science.gov (United States)

    Devakul, Trithep; Singh, Rajiv R. P.

    2014-08-01

    We calculate the area, edge, and corner Renyi entanglement entropies in the ground state of the transverse-field Ising model, on a simple-cubic lattice, by high-field and low-field series expansions. We find that while the area term is positive and the line term is negative as required by strong subadditivity, the corner contributions are positive in three dimensions. Analysis of the series suggests that the expansions converge up to the physical critical point from both sides. The leading area-law Renyi entropies match nicely from the high- and low-field expansions at the critical point, forming a sharp cusp there. We calculate the coefficients of the logarithmic divergence associated with the corner entropy and compare them with conformal field theory results with smooth interfaces and find a striking correspondence.

  3. Energy Density Bounds in Cubic Quasi-Topological Cosmology

    CERN Document Server

    dS, U Camara; Sotkov, G M

    2013-01-01

    We investigate the thermodynamical and causal consistency of cosmological models of the cubic Quasi-Topological Gravity (QTG) in four dimensions, as well as their phenomenological consequences. Specific restrictions on the maximal values of the matter densities are derived by requiring the apparent horizon's entropy to be a non-negative, non-decreasing function of time. The QTG counterpart of the Einstein-Hilbert (EH) gravity model of linear equation of state is studied in detail. An important feature of this particular QTG cosmological model is the new early-time acceleration period of the evolution of the Universe, together with the standard late-time acceleration present in the original EH model. The QTG correction to the causal diamond's volume is also calculated.

  4. Room temperature quantum emission from cubic silicon carbide nanoparticles.

    Science.gov (United States)

    Castelletto, Stefania; Johnson, Brett C; Zachreson, Cameron; Beke, David; Balogh, István; Ohshima, Takeshi; Aharonovich, Igor; Gali, Adam

    2014-08-26

    The photoluminescence (PL) arising from silicon carbide nanoparticles has so far been associated with the quantum confinement effect or to radiative transitions between electronically active surface states. In this work we show that cubic phase silicon carbide nanoparticles with diameters in the range 45-500 nm can host other point defects responsible for photoinduced intrabandgap PL. We demonstrate that these nanoparticles exhibit single photon emission at room temperature with record saturation count rates of 7 × 10(6) counts/s. The realization of nonclassical emission from SiC nanoparticles extends their potential use from fluorescence biomarker beads to optically active quantum elements for next generation quantum sensing and nanophotonics. The single photon emission is related to single isolated SiC defects that give rise to states within the bandgap.

  5. Spatial 't Hooft loop to cubic order in hot QCD

    CERN Document Server

    Giovannangeli, P

    2002-01-01

    Spatial 't Hooft loops of strength k measure the qualitative change in the behaviour of electric colour flux in confined and deconfined phase of SU (N) gauge theory. They show an area law in the deconfined phase, known analytica lly to two loop order with a ``k-scaling'' law k(N-k). In this paper we comput e the O(g^3) correction to the tension. It is due to neutral gluon fields that get their mass through interaction with the wall. The simple k-scaling is lost in cubic order. The generic problem of non-convexity shows up in this order an d the cure is provided. The result for large N is explicitely given. We show tha t nonperturbative effects appear at O(g^5).

  6. Plasmon polaritons in cubic lattices of spherical metallic nanoparticles

    CERN Document Server

    Lamowski, Simon; Mariani, Eros; Weick, Guillaume; Pauly, Fabian

    2016-01-01

    We investigate theoretically plasmon polaritons in cubic lattices of interacting spherical metallic nanoparticles. Dipolar localized surface plasmons on each nanoparticle couple through the near field dipole-dipole interaction and form collective plasmons which extend over the whole metamaterial. Coupling these collective plasmons in turn to photons leads to plasmon polaritons. We derive within a quantum model general semi-analytical expressions to evaluate both plasmon and plasmon-polariton dispersions that fully account for nonlocal effects in the dielectric function of the metamaterial. Within this model, we discuss the influence of different lattice symmetries and predict related polaritonic gaps within the near-infrared to the visible range of the spectrum that depend on wavevector direction and polarization.

  7. Cubic Derivative Interactions and Asymptotic Dynamics of the Galileon Vacuum

    CERN Document Server

    De Arcia, Roberto; León, Genly; Nucamendi, Ulises; Quiros, Israel

    2015-01-01

    In this paper we apply the tools of the dynamical systems theory in order to uncover the whole asymptotic structure of the vacuum interactions of a galileon model with a cubic derivative interaction term. It is shown that, contrary to what occurs in the presence of background matter, the galileon interactions of vacuum appreciably modify the late-time cosmic dynamics. In particular, a local late-time attractor representing phantom behavior arises which is inevitably associated with a big rip singularity. It seems that the gravitational interactions of the background matter with the galileon screen the effects of the gravitational self-interactions of the galileon, thus erasing any potential modification of the late-time dynamics by the galileon vacuum processes. Unlike other galileon models inspired in the DGP scenario, self-accelerating solutions do not arise in this model.

  8. Quantum corrections for the cubic Galileon in the covariant language

    Science.gov (United States)

    Saltas, Ippocratis D.; Vitagliano, Vincenzo

    2017-05-01

    We present for the first time an explicit exposition of quantum corrections within the cubic Galileon theory including the effect of quantum gravity, in a background- and gauge-invariant manner, employing the field-reparametrisation approach of the covariant effective action at 1-loop. We show that the consideration of gravitational effects in combination with the non-linear derivative structure of the theory reveals new interactions at the perturbative level, which manifest themselves as higher-operators in the associated effective action, which' relevance is controlled by appropriate ratios of the cosmological vacuum and the Galileon mass scale. The significance and concept of the covariant approach in this context is discussed, while all calculations are explicitly presented.

  9. Lipidic cubic phase serial millisecond crystallography using synchrotron radiation

    Directory of Open Access Journals (Sweden)

    Przemyslaw Nogly

    2015-03-01

    Full Text Available Lipidic cubic phases (LCPs have emerged as successful matrixes for the crystallization of membrane proteins. Moreover, the viscous LCP also provides a highly effective delivery medium for serial femtosecond crystallography (SFX at X-ray free-electron lasers (XFELs. Here, the adaptation of this technology to perform serial millisecond crystallography (SMX at more widely available synchrotron microfocus beamlines is described. Compared with conventional microcrystallography, LCP-SMX eliminates the need for difficult handling of individual crystals and allows for data collection at room temperature. The technology is demonstrated by solving a structure of the light-driven proton-pump bacteriorhodopsin (bR at a resolution of 2.4 Å. The room-temperature structure of bR is very similar to previous cryogenic structures but shows small yet distinct differences in the retinal ligand and proton-transfer pathway.

  10. Hairy black holes in cubic quasi-topological gravity

    Science.gov (United States)

    Dykaar, Hannah; Hennigar, Robie A.; Mann, Robert B.

    2017-05-01

    We construct a class of five dimensional black hole solutions to cubic quasi-topological gravity with conformal scalar hair and study their thermodynamics. We find these black holes provide the second example of black hole λ-lines: a line of second order (continuous) phase transitions, akin to the fluid/superfluid transition of 4He. Examples of isolated critical points are found for spherical black holes, marking the first in the literature to date. We also find various novel and interesting phase structures, including an isolated critical point occurring in conjunction with a double reentrant phase transition. The AdS vacua of the theory are studied, finding ghost-free configurations where the scalar field takes on a non-zero constant value, in notable contrast to the five dimensional Lovelock case.

  11. Structure and energetics of nanotwins in cubic boron nitrides

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Shijian, E-mail: sjzheng@imr.ac.cn, E-mail: zrf@buaa.edu.cn; Ma, Xiuliang [Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Zhang, Ruifeng, E-mail: sjzheng@imr.ac.cn, E-mail: zrf@buaa.edu.cn [School of Materials Science and Engineering, and International Research Institute for Multidisciplinary Science, Beihang University, Beijing 100191 (China); Huang, Rong [Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200062 (China); Taniguchi, Takashi [National Institute for Materials Science, Tsukuba, Ibaraki 305-0044 (Japan); Ikuhara, Yuichi [Nanostructures Research Laboratory, Japan Fine Ceramics Center, Nagoya 456-8587 (Japan); Institute of Engineering Innovation, The University of Tokyo, Tokyo 113-8656 (Japan); Beyerlein, Irene J. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2016-08-22

    Recently, nanotwinned cubic boron nitrides (NT c-BN) have demonstrated extraordinary leaps in hardness. However, an understanding of the underlying mechanisms that enable nanotwins to give orders of magnitude increases in material hardness is still lacking. Here, using transmission electron microscopy, we report that the defect density of twin boundaries depends on nanotwin thickness, becoming defect-free, and hence more stable, as it decreases below 5 nm. Using ab initio density functional theory calculations, we reveal that the Shockley partials, which may dominate plastic deformation in c-BNs, show a high energetic barrier. We also report that the c-BN twin boundary has an asymmetrically charged electronic structure that would resist migration of the twin boundary under stress. These results provide important insight into possible nanotwin hardening mechanisms in c-BN, as well as how to design these nanostructured materials to reach their full potential in hardness and strength.

  12. THERMODYNAMIC PARAMETERS OF LEAD SULFIDE CRYSTALS IN THE CUBIC PHASE

    Directory of Open Access Journals (Sweden)

    T. O. Parashchuk

    2016-07-01

    Full Text Available Geometric and thermodynamic parameters of cubic PbS crystals were obtained using the computer calculations of the thermodynamic parameters within density functional theory method DFT. Cluster models for the calculation based on the analysis of the crystal and electronic structure. Temperature dependence of energy ΔE and enthalpy ΔH, Gibbs free energy ΔG, heat capacity at constant pressure CP and constant volume CV, entropy ΔS were determined on the basis of ab initio calculations of the crystal structure of molecular clusters. Analytical expressions of temperature dependences of thermodynamic parameters which were approximated with quantum-chemical calculation points have been presented. Experimental results compared with theoretically calculated data.

  13. Adaptive Predistortion Using Cubic Spline Nonlinearity Based Hammerstein Modeling

    Science.gov (United States)

    Wu, Xiaofang; Shi, Jianghong

    In this paper, a new Hammerstein predistorter modeling for power amplifier (PA) linearization is proposed. The key feature of the model is that the cubic splines, instead of conventional high-order polynomials, are utilized as the static nonlinearities due to the fact that the splines are able to represent hard nonlinearities accurately and circumvent the numerical instability problem simultaneously. Furthermore, according to the amplifier's AM/AM and AM/PM characteristics, real-valued cubic spline functions are utilized to compensate the nonlinear distortion of the amplifier and the following finite impulse response (FIR) filters are utilized to eliminate the memory effects of the amplifier. In addition, the identification algorithm of the Hammerstein predistorter is discussed. The predistorter is implemented on the indirect learning architecture, and the separable nonlinear least squares (SNLS) Levenberg-Marquardt algorithm is adopted for the sake that the separation method reduces the dimension of the nonlinear search space and thus greatly simplifies the identification procedure. However, the convergence performance of the iterative SNLS algorithm is sensitive to the initial estimation. Therefore an effective normalization strategy is presented to solve this problem. Simulation experiments were carried out on a single-carrier WCDMA signal. Results show that compared to the conventional polynomial predistorters, the proposed Hammerstein predistorter has a higher linearization performance when the PA is near saturation and has a comparable linearization performance when the PA is mildly nonlinear. Furthermore, the proposed predistorter is numerically more stable in all input back-off cases. The results also demonstrate the validity of the convergence scheme.

  14. Electrical and optical properties of silicon-doped gallium nitride polycrystalline films

    Indian Academy of Sciences (India)

    S R Bhattacharyya; A K Pal

    2008-02-01

    Si-doped GaN films in polycrystalline form were deposited on quartz substrates at deposition temperatures ranging from 300–623 K using r.f. sputtering technique. Electrical, optical and microstructural properties were studied for these films. It was observed that films deposited at room temperature contained mainly hexagonal gallium nitride (ℎ-GaN) while films deposited at 623 K were predominantly cubic (-GaN) in nature. The films deposited at intermediate temperatures were found to contain both the hexagonal and cubic phases of GaN. Studies on the variation of conductivity with temperature indicated Mott’s hopping for films containing -GaN while Efros and Shklovskii (E–S) hopping within the Coulomb gap was found to dominate the carrier transport mechanism in the films containing ℎ-GaN. A crossover from Mott’s hopping to E–S hopping in the `soft’ Coulomb gap was noticed with lowering of temperature for films containing mixed phases of GaN. The relative intensity of the PL peak at ∼ 2.73 eV to that for peak at ∼ 3.11 eV appearing due to transitions from deep donor to valence band or shallow acceptors decreased significantly at higher temperature. Variation of band gap showed a bowing behaviour with the amount of cubic phase present in the films.

  15. Cubic liquid crystalline nanoparticles: optimization and evaluation for ocular delivery of tropicamide.

    Science.gov (United States)

    Verma, Purnima; Ahuja, Munish

    2016-10-01

    The purpose of this study was to investigate the potential of cubic liquid crystalline nanoparticles for ocular delivery of tropicamide. Ultrasound-assisted fragmentation of cubic liquid crystalline bulk phases resulted in cubic liquid crystalline nanoparticles employing Pluronic F127 as dispersant. The effects of process variables such as sonication time, sonication amplitude, sonication depth, and pre-mixing time on particle size and polydispersity index was investigated using central composite design. The morphology of tropicamide-loaded nanoparticles was found to be nearly cubical in shape by transmission electron microscopy observation. Further, small angle X-ray scattering experiment confirmed the presence of D and P phase cubic structures in coexistence. The optimized tropicamide-loaded cubic nanoparticles showed in vitro corneal permeation of tropicamide across isolated porcine cornea comparable to its commercial preparation, Tropicacyl®. Ocular tolerance was evaluated by Hen's egg-chorioallantoic membrane test and histological studies. The results of in vivo mydriatic response study demonstrated a remarkably higher area under mydriatic response curve (AUC0→1440 min) values of cubic nanoparticles over Tropicacyl® indicating better therapeutic value of cubic nanoparticles. Furthermore, tropicamide-loaded cubic nanoparticles exhibited prolonged mydriatic effect on rabbits as compared to commercial conventional aqueous ophthalmic solution.

  16. Microstructure and texture analysis of YBCO thick film with peritectic growth on unoriented silver substrate

    Institute of Scientific and Technical Information of China (English)

    WANG Jue; MALOUFI Nabila; FAN Zhanguo; XUE Xiangxin; ESLING Claude

    2009-01-01

    YBCO textured thick film was prepared by direct periteetic growth method. Microstructure of the film was characterized. Electron backscattered diffraction (EBSD) technique was applied to the film for quantitative texture analysis. The main difficulty in resolving the ori-entation of YBCO pseudo-cubic structure was investigated. Automated orientation mapping was performed on YBCO thick film. Local tex-ture was presented in the form of orientation maps. Misorientation distribution and crystal growth characterization in the YBCO thick film were revealed. Large domains with well-aligned YBCO grains were formed. Each domain presented clear in-plane and out-plane textures.

  17. On the electronic transport properties of polycrystalline ZnSe films

    Science.gov (United States)

    Rusu, G. I.; Popa, M. E.; Rusu, G. G.; Salaoru, Iulia

    2003-09-01

    Zinc selenide (ZnSe) thin films were deposited onto glass substrates by the quasi-closed volume technique under vacuum. The film structure was studied by X-ray diffraction (XRD) technique, scanning electron microscopy and atomic force microscopy (AFM). The investigations showed that the films are polycrystalline and have a cubic (zinc blende) structure. The films with stable structure can be obtained if they, after deposition, were submitted to a heat treatment. The mechanism of electrical conduction is discussed in terms of Seto's model for polycrystalline semiconducting films. The values of optical energy gap have been determined from the absorption spectra.

  18. Theoretical investigation of the thermodynamic properties of metallic thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hung, Vu Van [Vietnam Education Publishing House, 81 Tran Hung Dao, Hanoi (Viet Nam); Phuong, Duong Dai [Hanoi National University of Education, 136 Xuan Thuy, Hanoi (Viet Nam); Hoa, Nguyen Thi [University of Transport and Communications, Lang Thuong, Dong Da, Hanoi (Viet Nam); Hieu, Ho Khac, E-mail: hieuhk@duytan.edu.vn [Institute of Research and Development, Duy Tan University, K7/25 Quang Trung, Danang (Viet Nam)

    2015-05-29

    The thermodynamic properties of metallic thin films with face-centered cubic structure at ambient conditions were investigated using the statistical moment method including the anharmonicity effects of thermal lattice vibrations. The analytical expressions of Helmholtz free energy, lattice parameter, linear thermal expansion coefficient, specific heats at the constant volume and constant pressure were derived in terms of the power moments of the atomic displacements. Numerical calculations of thermodynamic properties have been performed for Au and Al thin films and compared with those of bulk metals. This research proposes that thermodynamic quantities of thin films approach the values of bulk when the thickness of thin film is about 70 nm. - Highlights: • Thermodynamic properties of thin films were investigated using the moment method. • Expressions of Helmholtz energy, expansion coefficient, specific heats were derived. • Calculations for Au, Al thin films were performed and compared with those of bulks.

  19. Low temperature formation of higher-k cubic phase HfO{sub 2} by atomic layer deposition on GeO{sub x}/Ge structures fabricated by in-situ thermal oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, R., E-mail: zhang@mosfet.t.u-tokyo.ac.jp [School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan); Department of Information Science and Electronic Engineering, Zhejiang University, 38 Zheda Road, Hangzhou 310027 (China); Huang, P.-C.; Taoka, N.; Yokoyama, M.; Takenaka, M.; Takagi, S. [School of Engineering, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2016-02-01

    We have demonstrated a low temperature formation (300 °C) of higher-k HfO{sub 2} using atomic layer deposition (ALD) on an in-situ thermal oxidation GeO{sub x} interfacial layer. It is found that the cubic phase is dominant in the HfO{sub 2} film with an epitaxial-like growth behavior. The maximum permittivity of 42 is obtained for an ALD HfO{sub 2} film on a 1-nm-thick GeO{sub x} form by the in-situ thermal oxidation. It is suggested from physical analyses that the crystallization of cubic phase HfO{sub 2} can be induced by the formation of six-fold crystalline GeO{sub x} structures in the underlying GeO{sub x} interfacial layer.

  20. Structural properties of pure and Fe-doped Yb films prepared by vapor condensation

    Energy Technology Data Exchange (ETDEWEB)

    Rojas-Ayala, C., E-mail: chachi@cbpf.br [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180, RJ (Brazil); Facultad de Ciencias Físicas, Universidad Nacional Mayor de San Marcos, Lima, P.O.B. 14-149, Lima 14 (Peru); Passamani, E.C. [Departamento de Física, Universidade Federal do Espírito Santo, Vitória 29075-910, ES (Brazil); Suguihiro, N.M. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180, RJ (Brazil); Litterst, F.J. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180, RJ (Brazil); Institut für Physik der Kondensierten Materie, Technische Universität Braunschweig, 38106 Braunschweig (Germany); Baggio Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas, Rio de Janeiro 22290-180, RJ (Brazil)

    2014-10-15

    Ytterbium and iron-doped ytterbium films were prepared by vapor quenching on Kapton substrates at room temperature. Structural characterization was performed by X-ray diffraction and transmission electron microscopy. The aim was to study the microstructure of pure and iron-doped films and thereby to understand the effects induced by iron incorporation. A coexistence of face centered cubic and hexagonal close packed-like structures was observed, the cubic-type structure being the dominant contribution. There is an apparent thickness dependence of the cubic/hexagonal relative ratios in the case of pure ytterbium. Iron-clusters induce a crystalline texture effect, but do not influence the cubic/hexagonal volume fraction. A schematic model is proposed for the microstructure of un-doped and iron-doped films including the cubic- and hexagonal-like structures, as well as the iron distribution in the ytterbium matrix. - Highlights: • Pure and Fe-doped Yb films have been prepared by vapor condensation. • Coexistence of fcc- and hcp-type structures was observed. • No oxide phases have been detected. • Fe-clustering does not affect the fcc/hcp ratio, but favors a crystalline texture. • A schematic model is proposed to describe microscopically the microstructure.

  1. Theoretical Hardness of Zr3N4 Films

    Institute of Scientific and Technical Information of China (English)

    GAO Fa-Ming

    2011-01-01

    The structures,energetics and properties for orthohombic Zr3N4 and cubic Zr3N4 are calculated by first-principles calculations.The agreement between the predicted properties with available experimental data is excellent.The cubic phase has a smaller volume (by 11.2%) and a slightly higher total energy (by 0.3eV/pair),in comparison to the orthohombic phase.We elucidate the effects of stress on hardness of Zr3N4 films.The results show that the hardness of c-Zr3N4 increases up to 23% as the stress increases to 15 GPa.

  2. Influence of microstructure on the corrosion resistance of Fe-44Ni thin films

    Institute of Scientific and Technical Information of China (English)

    Lin Lu; Tian-cheng Liu; Xiao-gang Li

    2016-01-01

    An Fe–44Ni nanocrystalline (NC) alloy thin film was prepared through electrodeposition. The relation between the microstructure and corrosion behavior of the NC film was investigated using electrochemical methods and chemical analysis approaches. The results show that the NC film is composed of a face-centered cubic phase (γ-(Fe,Ni)) and a body-centered cubic phase (α-(Fe,Ni)) when it is annealed at temperatures less than 400°C. The corrosion resistance increases with the increase in grain size, and the corresponding corrosion process is controlled by oxygen reduction. The NC films annealed at 500°C and 600°C do not exhibit the same pattern, although their grain sizes are considerably large. This result is attributed to the existence of an anodic phase, Fe0.947Ni0.054, in these films. Under this condition, the related corrosion process is synthetically controlled by anodic dissolution and depolarization.

  3. Influence of microstructure on the corrosion resistance of Fe-44Ni thin films

    Science.gov (United States)

    Lu, Lin; Liu, Tian-cheng; Li, Xiao-gang

    2016-06-01

    An Fe-44Ni nanocrystalline (NC) alloy thin film was prepared through electrodeposition. The relation between the microstructure and corrosion behavior of the NC film was investigated using electrochemical methods and chemical analysis approaches. The results show that the NC film is composed of a face-centered cubic phase (γ-(Fe,Ni)) and a body-centered cubic phase (α-(Fe,Ni)) when it is annealed at temperatures less than 400°C. The corrosion resistance increases with the increase in grain size, and the corresponding corrosion process is controlled by oxygen reduction. The NC films annealed at 500°C and 600°C do not exhibit the same pattern, although their grain sizes are considerably large. This result is attributed to the existence of an anodic phase, Fe0.947Ni0.054, in these films. Under this condition, the related corrosion process is synthetically controlled by anodic dissolution and depolarization.

  4. The Gibbs Thomson effect in magnetron-sputtered austenitic stainless steel films

    Science.gov (United States)

    Cusenza, S.; Borchers, C.; Carpene, E.; Schaaf, P.

    2007-03-01

    Magnetron sputtering of austenitic stainless steel AISI 316, which has a face-centred cubic structure (γ), leads to films exhibiting a body-centred cubic (α) structure or a mixture of α- and γ-phases. The microstructure of the deposited films was studied by Mössbauer spectroscopy, x-ray diffraction and transmission electron microscopy. With increasing deposition temperature a phase transformation from α- to γ-phase was observed in these films. Instantaneous recording of the electromotive force shows that nickel content and deposition temperature are crucial factors for phase stability and phase formation. In room temperature deposited stainless steel films, the phase transformation after vacuum annealing can be described by the Johnson-Mehl-Avrami kinetic model. These phase transformations in stainless steel films during annealing can be explained with the Gibbs-Thomson effect, where the grain boundary energy raises the Gibbs free energy.

  5. The Gibbs-Thomson effect in magnetron-sputtered austenitic stainless steel films

    Energy Technology Data Exchange (ETDEWEB)

    Cusenza, S [Universitaet Goettingen, II Physikalisches Institut, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Borchers, C [Universitaet Goettingen, II Physikalisches Institut, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Carpene, E [Politecnico di Milano, Dipartimento di Fisica, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Schaaf, P [Universitaet Goettingen, II Physikalisches Institut, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany)

    2007-03-14

    Magnetron sputtering of austenitic stainless steel AISI 316, which has a face-centred cubic structure ({gamma}), leads to films exhibiting a body-centred cubic ({alpha}) structure or a mixture of {alpha}- and {gamma}-phases. The microstructure of the deposited films was studied by Moessbauer spectroscopy, x-ray diffraction and transmission electron microscopy. With increasing deposition temperature a phase transformation from {alpha}- to {gamma}-phase was observed in these films. Instantaneous recording of the electromotive force shows that nickel content and deposition temperature are crucial factors for phase stability and phase formation. In room temperature deposited stainless steel films, the phase transformation after vacuum annealing can be described by the Johnson-Mehl-Avrami kinetic model. These phase transformations in stainless steel films during annealing can be explained with the Gibbs-Thomson effect, where the grain boundary energy raises the Gibbs free energy.

  6. Size-dependent one-photon- and two-photon-pumped amplified spontaneous emission from organometal halide CH3NH3PbBr3 perovskite cubic microcrystals.

    Science.gov (United States)

    Zhang, Zhen-Yu; Wang, Hai-Yu; Zhang, Yan-Xia; Li, Kai-Jiao; Zhan, Xue-Peng; Gao, Bing-Rong; Chen, Qi-Dai; Sun, Hong-Bo

    2017-01-18

    In the past few years, organometal halide light-emitting perovskite thin films and colloidal nanocrystals (NCs) have attracted significant research interest in the field of highly purified illuminating applications. However, knowledge of photoluminescence (PL) characteristics, such as amplified spontaneous emission (ASE) of larger-sized perovskite crystals, is still relatively scarce. Here, we presented room-temperature size-dependent spontaneous emission (SE) and ASE of the organometal halide CH3NH3PbBr3 perovskite cubic microcrystals pumped through one-photon-(1P) and two-photon-(2P) excitation paradigms. The results showed that the optical properties of SE and ASE were sensitively dependent on the sizes of perovskite microcrystals irrespective of whether 1P or 2P excitation was used. Moreover, by comparing the spectral results of 1P- and 2P-pumped experiments, 2P pumping was found to be an effective paradigm to reduce thresholds by one order of magnitude. Finally, we carried out fluences-dependent time-resolved fluorescence dynamics experiments to study the underlying effects of these scale-dependent SE and ASE. We found that the photoluminescence (PL) recombination rates sensitively became faster with increasing carriers' densities, and that the ASE pumped from larger-sized CH3NH3PbBr3 perovskite cubic microcrystals showed faster lifetimes. This work shows that micro-sized perovskite cubic crystals could be the ideal patterns of perovskite materials for realizing ASE applications in the future.

  7. Electric quadrupole interaction in cubic BCC α-Fe

    Energy Technology Data Exchange (ETDEWEB)

    Błachowski, A.; Komędera, K. [Mössbauer Spectroscopy Division, Institute of Physics, Pedagogical University, ul. Podchorążych 2, PL-30-084 Kraków (Poland); Ruebenbauer, K., E-mail: sfrueben@cyf-kr.edu.pl [Mössbauer Spectroscopy Division, Institute of Physics, Pedagogical University, ul. Podchorążych 2, PL-30-084 Kraków (Poland); Cios, G.; Żukrowski, J. [AGH University of Science and Technology, Academic Center for Materials and Nanotechnology, Av. A. Mickiewicza 30, PL-30-059 Kraków (Poland); Górnicki, R. [RENON, ul. Gliniana 15/15, PL-30-732 Kraków (Poland)

    2016-07-15

    Mössbauer transmission spectra for the 14.41-keV resonant line in {sup 57}Fe have been collected at room temperature by using {sup 57}Co(Rh) commercial source and α-Fe strain-free single crystal as an absorber. The absorber was magnetized to saturation in the absorber plane perpendicular to the γ-ray beam axis applying small external magnetic field. Spectra were collected for various orientations of the magnetizing field, the latter lying close to the [110] crystal plane. A positive electric quadrupole coupling constant was found practically independent on the field orientation. One obtains the following value V{sub zz} = +1.61(4) × 10{sup 19} Vm{sup −2} for the (average) principal component of the electric field gradient (EFG) tensor under assumption that the EFG tensor is axially symmetric and the principal axis is aligned with the magnetic hyperfine field acting on the {sup 57}Fe nucleus. The nuclear spectroscopic electric quadrupole moment for the first excited state of the {sup 57}Fe nucleus was adopted as +0.17 b. Similar measurement was performed at room temperature using as-rolled polycrystalline α-Fe foil of high purity in the zero external field. Corresponding value for the principal component of the EFG was found as V{sub zz} = +1.92(4) × 10{sup 19} Vm{sup −2}. Hence, it seems that the origin of the EFG is primarily due to the local (atomic) electronic wave function distortion caused by the spin–orbit interaction between effective electronic spin S and incompletely quenched electronic angular momentum L. It seems as well that the lowest order term proportional to the product L·λ·S dominates, as no direction dependence of the EFG principal component is seen. The lowest order term is isotropic for a cubic symmetry as one has λ=λ 1 for cubic systems with the symbol 1 denoting unit operator and λ being the coupling parameter. - Highlights: • Precision of MS the same as MAPON • Real scans versus magnetization direction • A challenge

  8. New cubic structure compounds as actinide host phases

    Energy Technology Data Exchange (ETDEWEB)

    Stefanovsky, S V [SIA Radon, 7th Rostovskii lane 2/14, Moscow 119121 (Russian Federation); Yudintsev, S V; Livshits, T S, E-mail: profstef@mtu-net.ru [Institute of Geology of Ore Deposits, Petrography, Mineralogy and Geochemistry RAS, Staromonetny lane 35, Moscow 119017 (Russian Federation)

    2010-03-15

    Various compounds with fluorite (cubic zirconia) and fluorite-derived (pyrochlore, zirconolite) structures are considered as promising actinide host phases at immobilization of actinide-bearing nuclear wastes. Recently some new cubic compounds - stannate and stannate-zirconate pyrochlores, murataite and related phases, and actinide-bearing garnet structure compounds were proposed as perspective matrices for complex actinide wastes. Zirconate pyrochlore (ideally Gd{sub 2}Zr{sub 2}O{sub 7}) has excellent radiation resistance and high chemical durability but requires high temperatures (at least 1500 deg. C) to be produced by hot-pressing from sol-gel derived precursor. Partial Sn{sup 4+} substitution for Zr{sup 4+} reduces production temperature and the compounds REE{sub 2}ZrSnO{sub 7} may be hot-pressed or cold pressed and sintered at {approx}1400 deg. C. Pyrochlore, A{sub 2}B{sub 2}O{sub 7-x} (two-fold elementary fluorite unit cell), and murataite, A{sub 3}B{sub 6}C{sub 2}O{sub 20-y} (three-fold fluorite unit cell), are end-members of the polysomatic series consisting of the phases whose structures are built from alternating pyrochlore and murataite blocks (nano-sized modules) with seven- (2C/3C/2C), five- (2C/3C), eight- (3C/2C/3C) and three-fold (3C - murataite) fluorite unit cells. Actinide content in this series reduces in the row: 2C (pyrochlore) > 7C > 5C > 8C > 3C (murataite). Due to congruent melting murataite-based ceramics may be produced by melting and the firstly segregated phase at melt crystallization is that with the highest fraction of the pyrochlore modules in its structure. The melts containing up to 10 wt. % AnO{sub 2} (An = Th, U, Np, Pu) or REE/An fraction of HLW form at crystallization zoned grains composed sequentially of the 5C {yields} 8C {yields} 3C phases with the highest actinide concentration in the core and the lowest - in the rim of the grains. Radiation resistance of the 'murataite' is comparable to titanate pyrochlores. One

  9. Extending a Property of Cubic Polynomials to Higher-Degree Polynomials

    Science.gov (United States)

    Miller, David A.; Moseley, James

    2012-01-01

    In this paper, the authors examine a property that holds for all cubic polynomials given two zeros. This property is discovered after reviewing a variety of ways to determine the equation of a cubic polynomial given specific conditions through algebra and calculus. At the end of the article, they will connect the property to a very famous method…

  10. Deformation-induced structural transition in body-centred cubic molybdenum.

    Science.gov (United States)

    Wang, S J; Wang, H; Du, K; Zhang, W; Sui, M L; Mao, S X

    2014-03-07

    Molybdenum is a refractory metal that is stable in a body-centred cubic structure at all temperatures before melting. Plastic deformation via structural transitions has never been reported for pure molybdenum, while transformation coupled with plasticity is well known for many alloys and ceramics. Here we demonstrate a structural transformation accompanied by shear deformation from an original -oriented body-centred cubic structure to a -oriented face-centred cubic lattice, captured at crack tips during the straining of molybdenum inside a transmission electron microscope at room temperature. The face-centred cubic domains then revert into -oriented body-centred cubic domains, equivalent to a lattice rotation of 54.7°, and ~15.4% tensile strain is reached. The face-centred cubic structure appears to be a well-defined metastable state, as evidenced by scanning transmission electron microscopy and nanodiffraction, the Nishiyama-Wassermann and Kurdjumov-Sachs relationships between the face-centred cubic and body-centred cubic structures and molecular dynamics simulations. Our findings reveal a deformation mechanism for elemental metals under high-stress deformation conditions.

  11. The Normals to a Parabola and the Real Roots of a Cubic

    Science.gov (United States)

    Bains, Majinder S.; Thoo, J. B.

    2007-01-01

    The geometric problem of finding the number of normals to the parabola y = x[squared] through a given point is equivalent to the algebraic problem of finding the number of distinct real roots of a cubic equation. Apollonius solved the former problem, and Cardano gave a solution to the latter. The two problems are bridged by Neil's (semi-cubical)…

  12. Deformation-induced structural transition in body-centred cubic molybdenum

    Science.gov (United States)

    Wang, S. J.; Wang, H.; Du, K.; Zhang, W.; Sui, M. L.; Mao, S. X.

    2014-03-01

    Molybdenum is a refractory metal that is stable in a body-centred cubic structure at all temperatures before melting. Plastic deformation via structural transitions has never been reported for pure molybdenum, while transformation coupled with plasticity is well known for many alloys and ceramics. Here we demonstrate a structural transformation accompanied by shear deformation from an original -oriented body-centred cubic structure to a -oriented face-centred cubic lattice, captured at crack tips during the straining of molybdenum inside a transmission electron microscope at room temperature. The face-centred cubic domains then revert into -oriented body-centred cubic domains, equivalent to a lattice rotation of 54.7°, and ~15.4% tensile strain is reached. The face-centred cubic structure appears to be a well-defined metastable state, as evidenced by scanning transmission electron microscopy and nanodiffraction, the Nishiyama-Wassermann and Kurdjumov-Sachs relationships between the face-centred cubic and body-centred cubic structures and molecular dynamics simulations. Our findings reveal a deformation mechanism for elemental metals under high-stress deformation conditions.

  13. Application and Realization of the Computer Animation Design Based on Improved Cubic B-spline Curves

    Directory of Open Access Journals (Sweden)

    Ni Na

    2015-01-01

    Full Text Available Based on the application of the cubic B-spline curves in the computer animation design, taking into account the security and confidentiality of the information, this paper improves the animation design techniques by the use of the improved cubic B-spline curves. Finally, this paper provides the relevant C language programs of the animation design.

  14. The Normals to a Parabola and the Real Roots of a Cubic

    Science.gov (United States)

    Bains, Majinder S.; Thoo, J. B.

    2007-01-01

    The geometric problem of finding the number of normals to the parabola y = x[squared] through a given point is equivalent to the algebraic problem of finding the number of distinct real roots of a cubic equation. Apollonius solved the former problem, and Cardano gave a solution to the latter. The two problems are bridged by Neil's (semi-cubical)…

  15. Cubic Invariant Spherical Surface Harmonics in Conjunction With Diffraction Strain Pole-Figures

    NARCIS (Netherlands)

    Brakman, C.M.

    1986-01-01

    Four kinds of cubic invariant spherical surface harmonics are introduced. It has been shown previously that these harmonics occur in the equations relating measured diffraction (line-shift) elastic strain and macro-stresses generating these strains for the case of textured cubic materials. As a cons

  16. Stability of the high-pressure body-centered-cubic phase of helium

    NARCIS (Netherlands)

    Frenkel, D.

    1986-01-01

    This paper report absolute free-energy calculations of the fluid, body-centered-cubic, and face-centered-cubic phases of helium at T=327.04 K. We find that at and around this temperature the model potential proposed by Aziz et al. doe not yield a stable bcc phase. Quantum corrections do not alter th

  17. Stability of the high-pressure body-centered-cubic phase of helium

    OpenAIRE

    Frenkel, D.

    1987-01-01

    This paper report absolute free-energy calculations of the fluid, body-centered-cubic, and face-centered-cubic phases of helium at T=327.04 K. We find that at and around this temperature the model potential proposed by Aziz et al. doe not yield a stable bcc phase. Quantum corrections do not alter this conclusion

  18. Comparison of Dust Lattice Waves in Three-Dimensional Cubic Configurations

    Institute of Scientific and Technical Information of China (English)

    B. Farokhi; A. Hameditabar

    2012-01-01

    A three-dimensional (3D) dusty plasma crystalline with cubic configurations is considered. We calculate the interaction between particles up to distance √2a, implying the second-neighbor interactions for the simple cubic structure, the third-neighbor interactions for the body-centered cubic structure, and the forth-neighbor interactions the for face-centered cubic structure. Longitudinal and transverse dispersion relations are derived in arbitrary directions. The dispersion relations are studied in special directions, I.e. (1,0,0), (l,l,0)/√2, and (1,1, l)/√3- Study of dispersion relations with more neighbor interactions show that in some cases the results change physically.%A three-dimensional (3D) dusty plasma crystalline with cubic configurations is considered.We calculate the interaction between particles up to distance (√2)a,implying the second-neighbor interactions for the simple cubic structure,the third-neighbor interactions for the body-centered cubic structure,and the forth-neighbor interactions the for face-centered cubic structure.Longitudinal and transverse dispersion relations are derived in arbitrary directions.The dispersion relations are studied in special directions,i.e.(1,0,0),(1,1,0)/(√2),and (1,1,1)/(√3).Study of dispersion relations with more neighbor interactions show that in some cases the results change physically.

  19. Extending a Property of Cubic Polynomials to Higher-Degree Polynomials

    Science.gov (United States)

    Miller, David A.; Moseley, James

    2012-01-01

    In this paper, the authors examine a property that holds for all cubic polynomials given two zeros. This property is discovered after reviewing a variety of ways to determine the equation of a cubic polynomial given specific conditions through algebra and calculus. At the end of the article, they will connect the property to a very famous method…

  20. Thermodynamic properties of the cubic plutonium hydride solid solution

    Energy Technology Data Exchange (ETDEWEB)

    Haschke, J M

    1981-12-01

    Pressure, temperature, and composition data for the cubic solid solution plutonium hydride phase, PuH/sub x/, have been measured by microbalance methods. Integral enthalpies and entropies of formation have been evaluated for the composition range 1.90 less than or equal to X less than or equal to 3.00. At 550/sup 0/K, ..delta..H/sup 0/ /sub f/(PuH/sub x/(s)) varies linearly from approximately (-38 +- 1) kcal mol/sup -1/ at PuH/sub 190/ to (-50 +- 1 kcal mol/sup -1/) at PuH/sub 3/ /sub 00/. Thermochemical values obtained by reevaluating tensimetric data from the literature are in excellent agreement with these results. Isotopic effects have been quantified by comparing the results for hydride and deuteride, and equations are presented for predicting ..delta..H/sup 0/ /sub f/ and ..delta..S/sup 0/ /sub f/ values for PuH/sub x/(s) and PuD/sub x/(s).