Simulation of chemical bond distributions and phase transformation in carbon chains

In the present work we develop a Monte Carlo algorithm of the carbon chains ordered into 2D hexagonal array. The chemical bond of the chained carbon is computed from 1 K to 1300 K. Our model confirms that the beta phase is more energetic preferable at low temperatures but the system prefers to switch into alpha phase at high temperatures. Based on the thermal effect on the bond distributions of the carbon chains, the bond softening temperature is observed at 500 K. The bond softening temperature is higher in the presence of interstitial doping but it does not change with the length of nanowire. The elastic modulus of the carbon chains is 1.7 TPa at 5 K and the thermal expansion is +7 × 10−5 K−1 at 300 K via monitoring the collective atomic vibrations and bond distributions. Thermal fluctuation in terms of heat capacity as a function of temperatures is computed in order to study the phase transition across melting point. The heat capacity anomaly initiates around 3800 K. © 2016 Elsevier Lt

ART-XC: A Medium-energy X-ray Telescope System for the Spectrum-R-Gamma Mission

The ART-XC instrument is an X-ray grazing-incidence telescope system in an ABRIXAS-type optical configuration optimized for the survey observational mode of the Spectrum-RG astrophysical mission which is scheduled to be launched in 2011. ART-XC has two units, each equipped with four identical X-ray multi-shell mirror modules. The optical axes of the individual mirror modules are not parallel but are separated by several degrees to permit the four modules to share a single CCD focal plane detector, 1/4 of the area each. The 450-micron-thick pnCCD (similar to the adjacent eROSITA telescope detector) will allow detection of X-ray photons up to 15 keV. The field of view of the individual mirror module is about 18 x 18 arcminutes(exp 2) and the sensitivity of the ART-XC system for 4 years of survey will be better than 10(exp -12) erg s(exp -1) cm(exp -2) over the 4-12 keV energy band. This will allow the ART-XC instrument to discover several thousand new AGNs

Superconductivity in ultra-thin carbon nanotubes and carbyne-nanotube composites: An ab-initio approach

The superconductivity of the 4-Å single-walled carbon nanotubes (SWCNTs) was discovered more than a decade ago, and marked the breakthrough of finding superconductivity in pure elemental undoped carbon compounds. The van Hove singularities in the electronic density of states at the Fermi level in combination with a large Debye temperature of the SWCNTs are expected to cause an impressively large superconducting gap. We have developed an innovative computational algorithm specially tailored for the investigation of superconductivity in ultrathin SWCNTs. We predict the superconducting transition temperature of various thin carbon nanotubes resulting from electron-phonon coupling by an ab-initio method, taking into account the effect of radial pressure, symmetry, chirality (N,M) and bond lengths. By optimizing the geometry of the carbon nanotubes, a maximum Tc of 60 K is found. We also use our method to calculate the Tc of a linear carbon chain embedded in the center of (5,0) SWCNTs. The strong curvature in the (5,0) carbon nanotubes in the presence of the inner carbon chain provides an alternative path to increase the Tc of this carbon composite by a factor of 2.2 with respect to the empty (5,0) SWCNTs. © 2017 Elsevier Lt

Kinetics of domain structure in KTiOPO4 crystals

The equipment of the Ural Center for Shared Use “Modern Nanotechnology” UrFU was used. The research was made possible by RFBR (16-02-00724 a) and by Government of the Russian Federation (Act 211, Agreement 02.A03.21.0006)

FILMS OF LINEAR CHAINED CARBON ON COPPER SUBSTRATE: MODELING AND RAMAN CHARACTERIZATION

The work is aimed to combine the experimental and calculated Raman spectra for the straight and helical carbyne crystal structural model. The influence of (100), (110) and (111) copper substrates is taken into account. DFT calculations establish the dependence between chain structure, phonon frequencies and Raman susceptibilities, giving interpretation to experimental Raman bands. As a sample system, we used the 20 – 400 nm films of chains on copper substrate synthesized by ion-assisted condensation in a high vacuum where the flows of carbon and Ar gas ions impinge on the substrate

Status of ART-XC/SRG Instrument

Spectrum Roentgen Gamma (SRG) is an X-ray astrophysical observatory, developed by Russia in collaboration with Germany. The mission will be launched in March 2016 from Baikonur, by a Zenit rocket with a Fregat booster and placed in a 6-month-period halo orbit around L2. The scientific payload consists of two independent telescopes - a soft-x-ray survey instrument, eROSITA, being provided by Germany and a medium-x-ray-energy survey instrument ART-XC being developed by Russia. ART-XC will consist of seven independent, but co-aligned, telescope modules. The NASA Marshall Space Flight Center (MSFC) is fabricating the flight mirror modules for the ART-XC/SRG. Each mirror module will be aligned with a focal plane CdTe double-sided strip detectors which will operate over the energy range of 6-30 keV, with an angular resolution of less than 1, a field of view of approximately 34 and an expected energy resolution of about 10 percent at 14 keV

CALCULATION OF THE ENERGY STRUCTURE AND OPTICAL PROPERTIES OF THE SURFACE OF ZINC-CONTAINING PARTICLES IN SILICON DIOXIDE FILMS

The aim of this work is to study the optical properties of the nanoparticle-matrix interface for SiO2 implanted with zinc ions. The structural models of the interfaces silica-Zn, silica-ZnO and silica-willemite are selected and their geometric optimization is carried out

ART-XC Instrument on Board of the SRG Mission

No abstract availabl

The ART-XC telescope on board the SRG observatory

ART-XC (Astronomical Roentgen Telescope - X-ray Concentrator) is the hard X-ray instrument with grazing incidence imaging optics on board the Spektr-Roentgen-Gamma (SRG) observatory. The SRG observatory is the flagship astrophysical mission of the Russian Federal Space Program, which was successively launched into orbit around the second Lagrangian point (L2) of the Earth-Sun system with a Proton rocket from the Baikonur cosmodrome on 13 July 2019. The ART-XC telescope will provide the first ever true imaging all-sky survey performed with grazing incidence optics in the 4-30 keV energy band and will obtain the deepest and sharpest map of the sky in the energy range of 4-12 keV. Observations performed during the early calibration and performance verification phase as well as during the on-going all-sky survey that started on 12 Dec. 2019 have demonstrated that the in-flight characteristics of the ART-XC telescope are very close to expectations based on the results of ground calibrations. Upon completion of its 4-year all-sky survey, ART-XC is expected to detect ~5000 sources (~3000 active galactic nuclei, including heavily obscured ones, several hundred clusters of galaxies, ~1000 cataclysmic variables and other Galactic sources), and to provide a high-quality map of the Galactic background emission in the 4-12 keV energy band. ART-XC is also well suited for discovering transient X-ray sources. In this paper, we describe the telescope, results of its ground calibrations, major aspects of the mission, the in-flight performance of ART-XC and first scientific results.Comment: 19 pages, 30 figures, accepted for publication in Astronomy and Astrophysic