23 research outputs found
Mass recovery of carbonated fabrics of glass fibres after isothermal heating
Acknowledgement: Authors acknowledge financial support from Latvian National Program IMIS2Leaching of Na+ ions in sodium oxide (Na2O) and silica (SiO2) containing glass is well investigated mainly due to its weak weathering. The object of this study was naturally (at room conditions) leached, steady state product on surface of sodium oxide-silica-alumina (Al2O3) glass fibers (in fabric) in a form of shell of "glyed" trona crystals as a result of interaction of leached Na+ ions and H2O and CO2 from atmosphere. There are presented results of continued former investigation of mass loss by isothermal heating of fabric and mass recovery in different atmospheres during the first phase of adsorption (at least 0.25h) without changes of state of crystals obtained during preheating at different temperatures. There are observed two ways of decomposition of trona (Na3H (CO3)2•2H2O) with its beginning at about 55-570C and 73-750C. The regression analysis of mass restoring in different atmospheres indicates to simultaneous and exponential mass increase by physical adsorption of CO2 and H2O having the different parameters of exponents vs time. Decomposition of trona is discussed in terms of parameters of exponent vs preheating temperature.Institute of Solid State Physics, University of Latvia as the Center of Excellence has received funding from the European Union’s Horizon 2020 Framework Programme H2020-WIDESPREAD-01-2016-2017-TeamingPhase2 under grant agreement No. 739508, project CAMART
Amorphous ultra-wide bandgap ZnOx thin films deposited at cryogenic temperatures
Crystalline wurtzite zinc oxide (w-ZnO) can be used as a wide band gap
semiconductor for light emitting devices and for transparent or high
temperature electronics. The use of amorphous zinc oxide (a-ZnO) can be an
advantage in these applications. In this paper we report on X-ray amorphous
a-ZnOx thin films (~500 nm) deposited at cryogenic temperatures by reactive
magnetron sputtering. The substrates were cooled by a nitrogen flow through the
copper substrate holder during the deposition. The films were characterized by
X-ray diffraction (XRD), Raman, infrared, UV-Vis-NIR spectroscopies, and
ellipsometry. The a-ZnOx films on glass and Ti substrates were obtained at the
substrate holder temperature of approximately -100 oC. New vibration bands at
201, 372, and 473 cm-1 as well as O-H stretch and bend absorption bands in the
a-ZnOx films were detected by FTIR spectroscopy. Raman spectra showed
characteristic ZnO2 peaks at 386 and 858 cm-1 attributed to the peroxide ion
O22- stretching and libration modes, respectively. In addition, the films
contain neutral and ionized O2 and O2- species. The a-ZnOx films are highly
transparent in the visible light range (approx. 87%) and exhibit a refractive
index of 1.68 at 2.25 eV (550 nm). An optical band gaps is 4.65 eV with an
additional band edge absorption feature at 3.50 eV. It has been shown that the
deposition on actively cooled substrates can be a suitable technique to obtain
low temperature phases that cannot be deposited at room temperature.Comment: 24 pages, 8 figure
Raman Spectroscopy Evidence of 1:1:1 Complex Formation during Dissolution of WO3 in a Melt of K2S2O7: K2SO4
Reactive pulsed direct current magnetron sputtering deposition of semiconducting yttrium oxide thin film in ultralow oxygen atmosphere: A spectroscopic and structural investigation of growth dynamics
An experimental investigation was conducted to explore spectroscopic and
structural characterization of semiconducting yttrium oxide thin film deposited
at 623 K (+/- 5K) utilizing reactive pulsed direct current magnetron
sputtering. Based on the results obtained from both x-ray diffraction and
transmission electron microscope measurements, yttrium monoxide is very likely
formed in the transition region between {\beta}-Y2O3 and {\alpha}-Y2O3, and
accompanied by the crystalline Y2O3. Resulting from either the low energy
separation between 4d and 5s orbitals and/or different spin states of the
corresponding orbitals' sublevels, the stability of monoxide is most presumably
self-limited by the size of the crystal in thermodynamic terms. This behavior
develops a distortion in the structure of the crystal compared to the metal
oxide cubic structure and it also effectuates the arrangement in
nanocrystalline/amorphous phase. In addition to this, spectroscopic
ellipsometry denotes that the semiconducting yttrium oxide has the dominant,
mostly amorphous, formation character over crystalline Y2O3. Our purpose, by
means of the current findings, is to advance the understanding of formation
kinetics/conditions of yttrium with an unusual valency (2+)