Search results for "Phase diagrams"
showing 10 items of 10 documents
Theoretical Predictions and experimental determination of cloud point curves for polymeric solutions: an application to the ternary system Poly-lacti…
2011
The lattice fluid model with specific interactions was applied to the ternary system Poly-L-lactic-acid (PLLA)-dioxane-water. Model parameters were determined by fitting experimental data. The as-obtained parameters were used to calculate the complete phase diagram. An experimental apparatus for cloud point measurements, which is under construction, is presented.
Competition of electron-phonon mediated superconductivity and Stoner magnetism on a flat band
2018
The effective attractive interaction between electrons, mediated by electron-phonon coupling, is a well-established mechanism of conventional superconductivity. In metals exhibiting a Fermi surface, the critical temperature of superconductivity is exponentially smaller than the characteristic phonon energy. Therefore, such superconductors are found only at temperatures below a few kelvin. Systems with flat energy bands have been suggested to cure the problem and provide a route to room-temperature superconductivity, but previous studies are limited to only BCS models with an effective attractive interaction. Here we generalize Eliashberg's theory of strong-coupling superconductivity to syst…
High Entropy Alloys for Energy Conversion and Storage: A Review of Grain Boundary Wetting Phenomena
2022
This research was funded by the Russian Ministry of Science and Higher Education (contract no. 075-15-2021-945 grant no. 13.2251.21.0013). Support from the University of the Basque Country (project GIU19/019) and from the Basque Government (project IT1714-22) is also acknowledged.
Phase diagram of dirty two-band superconductors and observability of impurity-induced s + i s state
2017
We investigate the phase diagram of dirty two-band superconductors. This paper primarily focuses on the properties and observability of the time-reversal symmetry-breaking s + is superconducting states, which can be generated in two-band superconductors by interband impurity scattering. We show that such states can appear in two distinct ways. First, according to a previously discussed scenario, the s + is state can form as an intermediate phase at the impurity-driven crossover between s± and s++ states. We show that there is a second scenario where domains of the s + is state exists in the form of an isolated dome inside the s± domain, completely detached from the transition between s± and…
X-ray diffraction measurements of Mo melting to 119 GPa and the high pressure phase diagram
2009
In this paper, we report angle-dispersive X-ray diffraction data of molybdenum melting, measured in a double-sided laser-heated diamond-anvil cell up to a pressure of 119 GPa and temperatures up to 3400 K. The new melting temperatures are in excellent agreement with earlier measurements up to 90 GPa that relied on optical observations of melting and in strong contrast to most theoretical estimates. The X-ray measurements show that the solid melts from the bcc structure throughout the reported pressure range and provide no evidence for a high temperature transition from bcc to a close-packed structure, or to any other crystalline structure. This observation contradicts earlier interpretation…
Grain Boundary Wetting Phenomena in High Entropy Alloys Containing Nitrides, Carbides, Borides, Silicides, and Hydrogen: A Review
2021
This review was written during the preparation of M-era.Net full proposal “Grain boundaries in multicomponent alloys without principal component” (A.Ko., A.Ku., G.L., and E.R., application No 9345). We also acknowledge the support of the KIT-Publication Fund of the Karlsruhe Institute of Technology. The Institute of Solid State Physics, University of Latvia, as a 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 CAMART2.
Direct synthesis of dimethyl carbonate with supercritical carbon dioxide: characterization of a key organotin oxide intermediate
2006
The direct synthesis of dimethyl carbonate (DMC) using carbon dioxide as solvent and reagent for its fixation to methanol was explored with din-butyldimethoxystannane in order to get insight into the reaction mechanism for activity improvement. Catalytic runs including recycling experiments allowed isolation and characterization by NMR, IR, and single-crystal X-ray diffraction of a new tin complex containing 10 tin atoms. This compound could be prepared independently and is considered as a resting species. The yield of DMC is highest under 20 MPa pressure that fits with a monophasic supercritical medium in agreement with fluid phase equilibria calculations. In line, preliminary kinetics and…
Configurational entropy of microemulsions : The fundamental length scale
1993
Phenomenological models have been quite successful in characterizing both the various complex phases and the corresponding phase diagrams of microemulsions. In some approaches, e.g., the random mixing model (RMM), the lattice parameter is of the order of the dimension of an oil or water domain and has been used as a length scale for computing a configurational entropy, the so‐called entropy of mixing, of the microemulsion. In the central and material section of this paper (Sec. III), we show that the fundamental length scale for the calculation of the entropy of mixing is of the order of the cube root of the volume per molecule—orders of magnitude smaller than the dimension of such a domain…
The Grain Boundary Wetting Phenomena in the Ti-Containing High-Entropy Alloys: A Review
2021
In this review, the phenomenon of grain boundary (GB) wetting by melt is analyzed for multicomponent alloys without principal components (also called high-entropy alloys or HEAs) containing titanium. GB wetting can be complete or partial. In the former case, the liquid phase forms the continuous layers between solid grains and completely separates them. In the latter case of partial GB wetting, the melt forms the chain of droplets in GBs, with certain non-zero contact angles. The GB wetting phenomenon can be observed in HEAs produced by all solidification-based technologies. GB leads to the appearance of novel GB tie lines Twmin and Twmax in the multicomponent HEA phase diagrams. The so-cal…
Phase diagram of dirty two-band superconductors and observability of impurity-induced $s+is$ state
2016
We investigate the phase diagram of dirty two-band superconductors. This paper primarily focuses on the properties and observability of the time-reversal symmetry-breaking $s+is$ superconducting states, which can be generated in two-band superconductors by interband impurity scattering. We show that such states can appear in two distinct ways. First, according to a previously discussed scenario, the $s+is$ state can form as an intermediate phase at the impurity-driven crossover between $s_{\pm}$ and $s_{++}$ states. We show that there is a second scenario where domains of the $s+is$ state exists in the form of an isolated dome inside the $s_{\pm}$ domain, completely detached from the transi…