393 research outputs found
Photoconductive detection of hydrogen in ZnO and rutile TiO2
Hydrogen donors in ZnO and rutile TiO2 are probed by means of
photoconductivity and IR absorption. It is shown that the O–H bonds giving
rise to the local vibrational modes (LVMs) of interstitial hydrogen at 3611
and 3290 cm−1 in the case of ZnO and TiO2, respectively, also occur in the
photoconductivity spectra as Fano resonances. The effects of isotope
substitution, concentration, sample thickness, influence of other donors
present in both oxides are considered. Based on the shape and frequency of
these resonances, it is concluded that the apparent ionization energy of
interstitial hydrogen in rutile TiO2 is less than 300 meV. By a direct
comparison, we also demonstrate that photoconductive detection of LVMs of
defects in thin semiconductor films is superior to the standard IR absorption
UV continuum emission and diagnostics of hydrogen-containing non-equilibrium plasmas
For the first time the emission of the radiative dissociation continuum of
the hydrogen molecule ( electronic
transition) is proposed to be used as a source of information for the
spectroscopic diagnostics of non-equilibrium plasmas. The detailed analysis of
excitation-deactivation kinetics, rate constants of various collisional and
radiative transitions and fitting procedures made it possible to develop two
new methods of diagnostics of: (1) the ground state
vibrational temperature from the relative intensity
distribution, and (2) the rate of electron impact dissociation
(d[\mbox{H_{2}}]/dt)_{\text{diss}} from the absolute intensity of the
continuum. A known method of determination of from relative
intensities of Fulcher- bands was seriously corrected and simplified
due to the revision of transition probabilities and cross sections of
electron impact excitation. General considerations are illustrated
with examples of experiments in pure hydrogen capillary-arc and H+Ar
microwave discharges.Comment: REVTeX, 25 pages + 12 figures + 9 tables. Phys. Rev. E, eprint
replaced because of resubmission to journal after referee's 2nd repor
On the method of photoconductive detection of defects in semiconductors by vibrational mode-related Fano resonances
The method of photoconductive detection of defect-related vibrational modes in semiconductors by Fano resonances is validated by a combined photoconductivity and infrared absorption study of the interstitial hydrogen donor in ZnO. Depth-resolved isotopic substitution experiments with varying concentrations of H and D show that the effect of vibrational mode-related absorption has to be taken into account in order to allow for an unambiguous interpretation of the experimental data. A quantitative model is presented which describes the influence of sample thickness, defect concentration, and the presence of other donors on the sign, magnitude, and shape of the Fano resonances. Implications for the photoconductive detection of defect-related vibrational modes are discusse
Normal-state resistivity anisotropy in underdoped RBa_2Cu_3O_{6+x} crystals
We have revealed new features in the out-of-plane resistivity rho_c of
heavily underdoped RBa_2Cu_3O_{6+x} (R=Tm,Lu) single crystals, which give
evidence for two distinct mechanisms contributing the c-axis transport. We have
observed a crossover towards "metal-like" (d rho_c/d T > 0) behavior at the
temperature T_m which quickly increases with decreasing doping. The
"metal-like" conductivity contribution dominates at T < T_m and provides a
saturation of the resistivity anisotropy, rho_c / rho_{ab}. The
antiferromagnetic ordering is found to block this "metal-like" part of the
c-axis conductivity and complete decoupling of CuO_2 planes, which may be the
reason of superconductivity disappearance.Comment: RevTex, 4 pages including 4 eps figures. To be published in
Phys.Rev.Let
Разработка виртуального 3D-тура по кафедре «Теплофизика и информатика в металлургии» УрФУ
This report presents the features of construction virtual 3D-round on chair «Thermophysics and computer science in metallurgy» Ural Federal University named after First President of Russia B. N. Yeltsin. Virtual 3D-round is posted on site http://tim.ustu.ru.В докладе представлены особенности создания виртуального 3D-тура по кафедре «Теплофизика и информатика в металлургии» «Теплофизика и информатика в металлургии» Института материаловедения и металлургии ФГАОУ ВПО «Уральский федеральный университет имени первого Президента России Б. Н. Ельцина». Виртуальный тур размещен на сайте кафедры (http://tim.ustu.ru в разделе «Виртуальный 3D-тур»)
Assessing the shape of the viscoplastic iron-ore zone in a blast furnace
A mathematical model permits assessment of the position and shape of the viscoplastic iron-ore zone (cohesion zone) in a blast furnace and identification of a rational configuration for this zone on the basis of readily available information regarding the blast furnace in the baseline period. The model also permits the solution of design problems with variation in the furnace parameters. Modeling results are outlined for the baseline and design periods. © 2013 Allerton Press, Inc
Mathematical modeling of radiant heat transfer in the melting furnace working space
The paper provides mathematical modelling results of radiation flow formation in the work space of the smelting (glassmaking, open-hearth) furnace with different heating patterns and flow distribution over the surface of the bath and enclosing structures. A significant influence of the flame length upon technical and economic parameters of furnace operation was found out. © Published under licence by IOP Publishing Ltd
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