Search results for "general [Globular clusters]"
showing 10 items of 27661 documents
Melting temperature prediction by thermoelastic instability: An ab initio modelling, for periclase (MgO)
2021
Abstract Melting temperature (TM) is a crucial physical property of solids and plays an important role for the characterization of materials, allowing us to understand their behavior at non-ambient conditions. The present investigation aims i) to provide a physically sound basis to the estimation of TM through a “critical temperature” (TC), which signals the onset of thermodynamic instability due to a change of the isothermal bulk modulus from positive to negative at a given PC-VC-TC point, such that (∂P/∂V)VC,TC = -(∂2F/∂V2) VC,TC = 0; ii) to discuss the case of periclase (MgO), for which accurate melting temperature observations as a function of pressure are available. Using first princip…
Comparative Study on Micromechanical Properties of ZnO:Ga and ZnO:In Luminiscent Ceramics
2021
The research has been supported by the Project ERANET RUS_ST#2017-051(Latvia) and #18-52-76002 (Russia). The Institute of Solid State Physics, University of Latvia as the Centre of Excellence has received funding from the European Union’s Horizon 2020 Framework, Program H2020-WIDESPREAD-01-2016-2017-Teaming Phase 2 under grant agreement No. 739508, project CAMART2.
Effect of surface finishing on the oxidation behaviour of a ferritic stainless steel
2017
Abstract The corrosion behaviour and the oxidation mechanism of a ferritic stainless steel, K41X (AISI 441), were evaluated at 800 °C in water vapour hydrogen enriched atmosphere. Mirror polished samples were compared to as-rolled K41X material. Two different oxidation behaviours were observed depending on the surface finishing: a protective double (Cr,Mn) 3 O 4 /Cr 2 O 3 scale formed on the polished samples whereas external Fe 3 O 4 and (Cr,Fe) 2 O 3 oxides grew on the raw steel. Moreover, isotopic marker experiments combined with SIMS analyses revealed different growth mechanisms. The influence of surface finishing on the corrosion products and growth mechanisms was apprehended by means o…
Wear and corrosion resistant performance of thermal-sprayed Fe-based amorphous coatings: A review
2019
Abstract Thermal sprayed Fe-based amorphous coatings exhibit excellent wear and corrosion resistance, and thus have been widely utilized for enhancing the performance of material surfaces. In this paper, important research progresses achieved in regards to deposition technologies and properties of thermal sprayed Fe-based amorphous coatings are reviewed. In particular, the dependence of wear and corrosion resistance of the coatings on processing parameters, e.g., kinetic energy, particle size, gas flow rate, and heat treatment temperature are summarized. Moreover, the utilization of reinforced phases and alloy elements for enhancing the wear and corrosion resistance of the coatings are pres…
Microstructure and electric properties of low-pressure plasma sprayed β-FeSi 2 based coatings
2017
Abstract Thermoelectric material β-FeSi 2 based coating was fabricated by the technique low-pressure plasma spray (LPPS) on the Al 2 O 3 substrate from different alloy powders. During the process LPPS, the phase transformation had occurred through the peritectoid, eutectoid reaction and their inverse reaction. The grain size of the as-sprayed β-FeSi 2 doped Co coatings was reduced comparing with the original feedstock powders, which implied the thermal conductivity could effectively decreased by the LPPS process. The room temperature electrical conductivity showed metal and semiconductor properties on the as-sprayed and annealed coatings. This method and the results could solve the problems…
Morphological and magnetic analysis of Fe nanostructures on W(110) by using scanning tunneling microscopy and Lorentz microscopy
2016
Abstract We investigated morphological features and magnetic properties of epitaxial Fe nanostructures (films, stripes and nanoparticles) on a W(110) surface with monoatomic steps preferentially along the direction. The nanostructures were prepared in ultra-high vacuum by using electron-beam evaporation and subsequent annealing at different temperatures. Scanning tunneling microscopy measurements in-situ revealed elongated Fe nanostructures with aspect ratios of up to . The observable shape and orientation (along or perpendicular to the monoatomic steps of the substrate) of the nanostructures depended substantially on the preparation parameters. By capping the system with 7 monolayers of Pt…
Luminescence properties of chlorine molecules in glassy SiO 2 and optical fibre waveguides
2017
The support from Latvian Research Program IMIS 2, project “Photonics and materials for photonics” is acknowledged. K.K. was partially supported by the Collaborative Research Project of Materials and Structures Laboratory, Tokyo Institute of Technology. The publication costs of this article were covered by the Estonian Academy of Sciences and the University of Tartu.
Outstanding nonlinear optical properties of methylammonium- and Cs-PbX3 (X = Br, I, and Br–I) perovskites: Polycrystalline thin films and nanoparticl…
2019
Metal Halide Perovskites (MHPs) have arisen as promising materials to construct cost-effective photovoltaic and light emission devices. The study of nonlinear optical properties of MHPs is necessary to get similar success in nonlinear photonic devices, which is practically absent in the literature. The determination of the third order nonlinear coefficients is typically done by the Z-scan technique, which is limited by the scattering of polycrystalline thin films. In this work, we have studied nonlinear optical properties of polycrystalline CH3NH3PbX3 (MAPbX3) thin films and colloidal CsPbX3 nanoparticles with three different bandgaps (X3 = I3, Br3, and Br1.5I1.5). Their bright generation o…
Corrosion of Welded Metal Structures of Mining Equipment
2018
Mining equipment made of welded metal structures is strongly affected by the corrosion phenomenon due to the working conditions. Initial research has shown that the corrosion phenomenon is most pronounced in the area of cross-welded joints and welded T-shaped joints. In the researches, there was made a chemical analysis of the welded construction material used respectively of the new material and it was observed a reduction in carbon concentration in the material used, but also a substantial increase in the sulfur concentration compared to the new material. The pronounced corrosion of the metallic structure is influenced by the chemical composition change because the sulfur is a grafitizin…
Epitaxial growth of perovskite oxide films facilitated by oxygen vacancies
2021
The authors would like to thank P. Yudin for valuable discussions, N. Nepomniashchaia for VASE studies, and S. Cichon for XPS analysis. The authors acknowledge support from the Czech Science Foundation (Grant No. 19-09671S), the European Structural and Investment Funds and the Ministry of Education, Youth and Sports of the Czech Republic through Programme ‘‘Research, Development and Education’’ (Project No. SOLID21 CZ.02.1.01/0.0/0.0/16-019/0000760), and ERA NET project Sun2Chem (E. K. and L. R.). Calculations have been done on the LASC Cluster in the ISSP UL.