2 results
Search Results
Now showing 1 - 2 of 2
- ItemMagnetocaloric properties of multicomponent Laves phase compounds and their composites(Bristol : IOP Publ., 2021) Ćwik, J.; Koshkid’ko, Yu; Nenkov, K.; Kolchugina, N.Heat capacity measurements have been performed for multicomponent (Ho0.9Er0.1)1-xGdxCo2 compounds with x = 0.05, 0.1, and 0.15. The isothermal magnetic entropy change, ΔSmag, allowing the estimation of the magnetocaloric effect, was determined based on the heat capacity measurements in magnetic fields up to 2 T. A numerical method, with the magnetic entropy change of individual (Ho0.9Er0.1)1-xGdxCo2 compounds, was used to calculate the optimal molar composition of the constituents and the resulting change of the isothermal magnetic entropy of composite, ΔScomp. The results show that proposed composite can be considered as a refrigerant material in magnetic refrigerators performing an Ericsson cycle in a temperature range of 90-130 K.
- ItemRedox chemistry in the pigment eumelanin as a function of temperature using broadband dielectric spectroscopy(Cambridge : Royal Society of Chemistry, 2019) Motovilov, K.A.; Grinenko, V.; Savinov, M.; Gagkaeva, Z.V.; Kadyrov, L.S.; Pronin, A.A.; Bedran, Z.V.; Zhukova, E.S.; Mostert, A.B.; Gorshunov, B.P.Conductive biomolecular systems are investigated for their promise of new technologies. One biomolecular material that has garnered interest for device applications is eumelanin. Its unusual properties have led to its incorporation in a wide set of platforms including transistor devices and batteries. Much of eumelanin's conductive properties are due to a solid state redox comproportionation reaction. However, most of the work that has been done to demonstrate the role of the redox chemistry in eumelanin has been via control of eumelanin's hydration content with scant attention given to temperature dependent behavior. Here we demonstrate for the first time consistency between hydration and temperature effects for the comproportionation conductivity model utilizing dielectric spectroscopy, heat capacity measurements, frequency scaling phenomena and recognizing that activation energies in the range of ∼0.5 eV correspond to proton dissociation events. Our results demonstrate that biomolecular conductivity models should account for temperature and hydration effects coherently.