Papers by Keyword: Oxide

Abstract: An advanced equipment for the charge version of deep level transient spectroscopy (Q-DLTS) and C-V measurements with newly developed software on LabView platform is presented. The ability to record several Q-DLTS behaviors with different rate windows simultaneously is the most important property of the equipment. Q-DLTS with excitation of the MOS structures by low-voltage step and time domain C-V measurements were used to determine interface properties. The contribution presents mainly results obtained on very-thin oxide/n-type crystalline Si structures prepared by oxidation at very low temperatures in nitric acid solutions with various concentrations.

Abstract: A brief update (2001 till the present) is presented on published records on nano- and microcomposites involving inorganic compounds as dispersed and matrix or support phase in powder or thin film/coating form. Properties and applications of the currently reported composite materials are also discussed. The status of this field of research is highlighted in a short analysis.

Abstract: Silicon Carbide MESFETs for microwave frequencies were made using a field-plated buried gate approach. The devices were fabricated using passivation oxides with different interface trap densities. By using a passivation oxide with a reduced interface trap density, grown in a sodium containing ambient, it was possible to achieve a very high continous wave output power density of the device: 8 W/mm at 3 GHz and 1 dB compression.

Abstract: Metal dusting behaviour of alloy800H was investigated in a laboratory-pressurized reactor where CO-H2-CO2-H2O gas mixtures flowed continuously, simulating the gas environments in actual syngas production plant. Four test conditions, having a variety of gas pressures and H2O contents, were conducted for a long rod specimen that was imposed thermal gradient of 777°C to 454°C in a longitudinal direction. After an exposure of 100h at high pressure, metal dusting has initiated with a bell-shape distribution on the test specimens at temperatures between 600°C and 700°C. Gas pressure has accelerated metal dusting even if the gas atmospheres had the same gas composition. On the contrary, metal dusting has been alleviated with increasing the H2O content in the test gas. Oxide scale characterisations were analyzed by using Raman spectroscopy and XPS at the test specimen surfaces exposed at different temperature. The ratio of a protective Cr2O3 scale to spinel oxides such as FeCr2O4 and MnCr2O4 has increased with increasing the exposure temperature, with reducing the gas pressure, and with lowering the H2O content. These behaviours have been interpreted from thermodynamic indices: carbon activity ac and the oxide scale integrity related to oxygen potential Po2 as a function of temperature.

Abstract: Metallic oxides are widely used in the industry; these are object of intensive research due to the versatility of their applications and the possibility of modulating their properties when the techniques and the procedures of obtaining them vary. The soft chemistry technique is shown as an option to obtain films of metallic oxide for their use optoelectronic devices. This work emphasizes the importance of applying dip-coating techniques of low cost for the industry with good results.

Abstract: The interaction between manganese(II) oxide and carbon in powder mixtures may give manganese carbides, condensed(c) and gaseous(g) manganese at different temperatures and pressures. The initial assumptions and results of thermodynamic modelling of this interaction in the temperature range 1600-2100 K at the pressures 0.1-1.0 MPa are presented in this paper.

Abstract: The kinetics of the isotope exchange between gaseous oxygen enriched with the 18O isotope and two LaMnO3+δ oxide samples – a nanopowder and a bulk nanocrystal – has been studied. The 18O isotope concentration has been measured by the acceleration nuclear microanalysis method. The coefficients of the volume and the nanograin boundary self-diffusion of oxygen have been evaluated at 500 °C. They are equal to 3.5·10 −20 and 1.5·10 −13 cm2/s, respectively.

Abstract: TiB2 coatings were plasma sprayed in air and were studied by XPS. There are five elements in the top surface of the studied coatings, namely, B, C, N, O and Ti. Oxygen pick-up in the coatings results in formation of oxides of boron and titanium. Nitrogen was shown to exist in N-Ti and O-N-Ti in the coating. Depending on the spraying parameters, mono-boride as well as di-boride was also detected in the studied coatings. With careful peak fitting it was shown that oxygen may exist in the coating as dissolved atomic O in addition to as lattice oxygen in the oxide of boron and titanium.

Abstract: The measurement of temperature based on the characteristic lifetime decay in luminescence intensity of dopant ions following excitation is described with illustrations drawn from europium doping in yttria-stabilized zirconia. The method is particularly attractive for making measurements in a temperature gradient, such as those in thermal barrier coatings.