Perspectives of application of nanotubes in modern composite building materials

There are described the perspectives of application a carbon and hydro silicate nanotubes in modern compositional materials. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2063

Properties of superhard nanostructured coatings Ti-Hf-Si-N

New superhard coatings based on Ti-Hf-Si-N featuring high physical and mechanical properties were fabricated. We employed a vacuum-arc source with HF stimulation and a cathode sintered from Ti-Hf-Si. Nitrides were fabricated using atomic nitrogen (N) or a mixture of Ar/N, which were leaked-in a chamber at various pressures and applied to a substrate potentials. RBS, SIMS, GT-MS, SEM with EDXS, XRD, and nanoindentation were employed as analyzing methods of chemical and phase composition of thin films. We also tested tribological and corrosion properties. The resulting coating was a two-phase, nanostructured nc-(Ti, Hf)N and α-Si3N4. Sizes of substitution solid solution nanograins changed from 3.8 to 6.5 nm, and an interface thickness surrounding α-Si3N4 varied from 1.2 to 1.8 nm. Coatings hardness, which was measured by nanoindentation was from 42.7 GPa to 48.6 GPa, and an elastic modulus was E = (450 to 515) GPa. The films stoichiometry was defined for various deposition conditions. It was found that in samples with superhard coatings of 42.7 to 48.6GPa hardness and lower roughness in comparison with other series of samples, friction coefficient was equal to 0.2, and its value did not change over all depth (thickness) of coatings. A film adhesion to a substrate was essentially high and reached 25MPa. В работе получены новые сверхтвердые покрытия на основе Ti-Hf-Si-N с высокими физико-механическими свойствами. В процессе синтеза методом вакуумно-дугового осаждения с применением ВЧ напряжения распылялся цельнолитой катод Ti-Hf-Si. Нитриды формировались в среде атомарного азота (N) или в смеси Ar/N, которые напускались в камеру при различных давлениях. Химический и фазовый составы тонких пленок анализировался методами RBS, SIMS, GT-MS, SEM с EDXS, РСА, а твердость определялась наноиндентированием. Исследовались трибологические и коррозионные свойства покрытий. Полученные покрытия являются двухфазными наноструктурированными nс-(Ti, Hf)N и α-Si3N4. Размеры нанозерен твердого раствора варьировались от 3,8 до 6,5 нм, а толщина окружающей оболочки α-Si3N4 менялась от 1,2 до 1,8 нм. Твердость покрытий H составляла 42,7 48,6 ГПа, а модуль упругости Е принимал значения от 450 ГПа до 515 ГПа. Определена стехиометрия пленок при различных условиях осаждения. Установлено, что в образцах сверхтвердых покрытий с твердостью 42,7 48.6 ГПа наблюдалась более низкая шероховатость по сравнению с другими образцами, коэффициент трения составлял 0,2, и его значение не изменялось по всей глубине (толщине) покрытия. Адгезия пленки к подложке достигла 25 МПа. У роботі отримані нові надтверді покриття на основі Ti-Hf-Sі-N з високими фізико-механічними властивостями. У процесі синтезу методом вакуумно-дугового осадження із застосуванням ВЧ напруги розпорошувався суцільнолитий катод Tі-Hf-Sі. Нітриди формувалися у середовищі атомарного азоту (N) або у суміші Ar/N, які напускалися у камеру при різних тисках. Хімічний і фазовий склади тонких плівок аналізувалися методами RBS, SІMS, GT-MS, SEM з EDXS, РСА, а твердість визначалася наноіндентуванням. Досліджувалися трибологічні та корозійні властивості покриттів. Отримані покриття є двофазними наноструктурованими nс-(Tі, Hf)N і -Sі3N4. Розміри нанозерен твердого розчину варіювалися від 3,8 до 6,5 нм, а товщина навколишньої оболонки -Sі3N4 змінювалася від 1,2 до 1,8 нм. Твердість покриттів H становила 42,7 48,6 ГПа, а модуль пружності Е приймав значення від 450 ГПа до 515 ГПа. Визначено стехіометрію плівок при різних умовах осадження. Встановлено, що у зразках надтвердих покриттів із твердістю 42,7 48.6 ГПа спостерігалася нижча шорсткість у порівнянні з іншими зразками, коефіцієнт тертя становив 0,2, і його значення не змінювалося за глибиною (товщиною) покриття. Адгезія плівки до підкладки досягла 25 МПа

Spin-orbit coupling control of anisotropy, ground state and frustration in 5d2 Sr2MgOsO6

The influence of spin-orbit coupling (SOC) on the physical properties of the 5d2 system Sr2MgOsO6 is probed via a combination of magnetometry, specific heat measurements, elastic and inelastic neutron scattering, and density functional theory calculations. Although a significant degree of frustration is expected, we find that Sr2MgOsO6 orders in a type I antiferromagnetic structure at the remarkably high temperature of 108 K. The measurements presented allow for the first accurate quantification of the size of the magnetic moment in a 5d2 system of 0.60(2) μB –a significantly reduced moment from the expected value for such a system. Furthermore, significant anisotropy is identified via a spin excitation gap, and we confirm by first principles calculations that SOC not only provides the magnetocrystalline anisotropy, but also plays a crucial role in determining both the ground state magnetic order and the size of the local moment in this compound. Through comparison to Sr2ScOsO6, it is demonstrated that SOC-induced anisotropy has the ability to relieve frustration in 5d2 systems relative to their 5d3 counterparts, providing an explanation of the high TN found in Sr2MgOsO6

Antideuteron and deuteron production in mid-central Pb+Pb collisions at 158AA GeV

Production of deuterons and antideuterons was studied by the NA49 experiment in the 23.5% most central Pb+Pb collisions at the top SPS energy of $\sqrt{s_{NN}}$=17.3 GeV. Invariant yields for $\bar{d}$ and $d$ were measured as a function of centrality in the center-of-mass rapidity range $-1.2<y<-0.6$. Results for $\bar{d}(d)$ together with previously published $\bar{p}(p)$ measurements are discussed in the context of the coalescence model. The coalescence parameters $B_2$ were deduced as a function of transverse momentum $p_t$ and collision centrality.Comment: 9 figure

Inclusive production of charged pions in p+C collisions at 158 GeV/c beam momentum

The production of charged pions in minimum bias p+C interactions is studied using a sample of 377000 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.8 GeV/c in transverse momentum and from -0.1 to 0.5 in Feynman x. Inclusive invariant cross sections are given on a grid of 270 bins per charge thus offering for the first time a dense coverage of the projectile hemisphere and of the cross-over region into the target fragmentation zone.Comment: 31 pages, 30 figures, submitted to European Journal of Physic

High p_T Spectra of Identified Particles Produced in Pb+Pb Collisions at 158GeV/nucleon Beam Energy

Transverse momentum spectra of pi^{+/-}, p, pbar, K^{+/-}, K^0_s and Lambda at midrapidity were measured at high p_T in Pb+Pb collisions at 158GeV/nucleon beam energy by the NA49 experiment. Particle yield ratios (p/pi, K/pi and Lambda/K^0_s) show an enhancement of the baryon/meson ratio for p_T>2GeV/c. The nuclear modification factor R_{CP} is extracted and compared to RHIC measurements and pQCD calculations.Comment: Quark Matter 2005 parallel section proceeding

Pion emission from the T2K replica target: method, results and application

The T2K long-baseline neutrino oscillation experiment in Japan needs precise predictions of the initial neutrino flux. The highest precision can be reached based on detailed measurements of hadron emission from the same target as used by T2K exposed to a proton beam of the same kinetic energy of 30 GeV. The corresponding data were recorded in 2007-2010 by the NA61/SHINE experiment at the CERN SPS using a replica of the T2K graphite target. In this paper details of the experiment, data taking, data analysis method and results from the 2007 pilot run are presented. Furthermore, the application of the NA61/SHINE measurements to the predictions of the T2K initial neutrino flux is described and discussed.Comment: updated version as published by NIM

Results on correlations and fluctuations from NA49

The large acceptance and high momentum resolution as well as the significant particle identification capabilities of the NA49 experiment at the CERN SPS allow for a broad study of fluctuations and correlations in hadronic interactions. In the first part recent results on event-by-event charge and p_t fluctuations are presented. Charge fluctuations in central Pb+Pb reactions are investigated at three different beam energies (40, 80, and 158 AGeV), while for the p_t fluctuations the focus is put on the system size dependence at 158 AGeV. In the second part recent results on Bose Einstein correlations of h-h- pairs in minimum bias Pb+Pb reactions at 40 and 158 AGeV, as well as of K+K+ and K-K- pairs in central Pb+Pb collisions at 158 AGeV are shown. Additionally, other types of two particle correlations, namely pi p, Lambda p, and Lambda Lambda correlations, have been measured by the NA49 experiment. Finally, results on the energy and system size dependence of deuteron coalescence are discussed.Comment: 10 pages, 12 figures, Presented at Quark Matter 2002, Nantes, France, Corrected error in Eq.

High p_T Spectra of Identified Particles Produced in Pb+Pb Collisions at 158A GeV Beam Energy

Results of the NA49 collaboration on the production of hadrons with large transverse momentum in Pb+Pb collisions at 158A GeV beam energy are presented. A range up to p_T = 4 GeV/c is covered. The nuclear modification factor R_CP is extracted for pions, kaons and protons, and the baryon to meson ratios p/pi+, pbar/pi- and Lambda/K^0_s are studied. All results are compared to other measurements at SPS and RHIC and to theoretical calculations.Comment: Submitted to J. Phys. G (Proceedings of the 9th International Conference on Strangeness in Quark Matter, Los Angeles, USA, March 26-31, 2006). 5 pages, 3 figure

Strangeness production at SPS energies

We present a summary of measurements of strange particles performed by the experiment NA49 in central and minimum bias Pb+Pb collisions in the beam energy range 20A - 158A GeV. New results on Xi production in central Pb+Pb collisions and on Lambda, Xi production in minimum bias collisions are shown. Transverse mass spectra and rapidity distributions of strange particles at different energies are compared. The energy dependence of the particle yields and ratios is discussed. NA49 measurements of the Lambda and Xi enhancement factors are shown for the first time.Comment: Submitted to J. Phys. G (Proceedings of the 9th International Conference on Strangeness in Quark Matter, Los Angeles, USA, March 26-31, 2006). 9 pages, 9 figure