AB Initio Estimations of Transport Properties of Solid Oxide Molybdates

This work is aimed at comprehensive theoretical study of Sr2MMoO6 molybdates with M = Ti, V, Cr, Mn, Fe, Co, Ni. It is shown that the experimentally observed variations of electronic conductivity in these compounds can be reasonably explained with the help of DFT calculations.Работа выполнена при поддержке Российского фонда фундаментальных исследований (РФФИ) в рамках проекта №19-79-10147

Intraspecific structure of the Coregonus lavaretus complex in water bodies of Siberia: a case of postglacial allopatric origin of Yukagirian whitefish

The results of morphological and genetic analyses of forms/species of the Coregonus lavaretus pidschian (Gmelin, 1789) complex from the Indigirka and Kolyma river basins are presented in the context of there being recent postglacial speciation events. It has been found that the studied whitefishes belong to the sparsely rakered and low lateral-line forms and have previously been described as Coregonus lavaretus pidschian n. jucagiricus Drjagin (Berg), 1932. Based on these characters, this whitefish does not differ from most Arctic whitefish populations (in particular from Coregonus lavaretus glacialis Kirillov, 1972). Analysis of variability of the ND1 gene (mtDNA) showed that whitefishes from the Indigirka and Kolyma basins belong to a distant phylogenetic lineage, which is significantly different from all previously studied whitefish lineages from the Ob, Yenisei, Lena, Anadyr, and Amur river basins. Analysis of variability of the ITS1 fragment (nDNA) showed that all studied forms/species (from Ob River to Amur River basins), including C. l. pidschian n. jucagiricus, have a tandem arrangement of two identical nucleotide fragments and very similar nucleotide composition of the ITS1 region. Based on contemporary data, this phylogenetic lineage of the C. pidschian complex could be considered a young postglacial allopatric species.info:eu-repo/semantics/acceptedVersio

ELECTRICAL TRANSPORT PROPERTIES OF MANGANESE-DOPED LANTHANUM-STRONTIUM FERRITES

During the research a number of solid oxides corresponding to chemical formula LaSr2(Fe1-xMnx)3O9-δ were synthesized, their phase homogeneity was confirmed. Electrical measurements at different outer experimental conditions for compounds with x = 0.1, 0.17, 0.33 were performed

ION TRANSPORT IN HIGHLY NONSTOICHIOMETRIC OXIDES WITH PEROVSKITE-LIKE STRUCTURE

Solid solutions with nominal composition Pr1-xYxBaCo2-yAlyO6-δ where x = 0, 0.1 and y = 0, 0.1 were synthesized, phase purity of the samples obtained was confirmed by XRD analysis. Cobaltites’ equilibrium oxygen content was determined via combination of coulometric titration and thermogravimetry. Thermal expansion of Pr1-xYxBaCo2-yAlyO6-δ oxides was studied with the help of dilatometry. Oxygen permeability was measured in a specially equipped device. Theoretical model was proposed and used for explanation of the data obtained

METHOD OF FIXATION OF TENDINOUS TRANSPLANT IN TENDOPLASTY OF DEEP FLEXOR MUSCLE OF FINGERS

The authors supposed the method of tendinous transplant application in tendoplasty of deep flexor muscle of fingers based on usage of a new variant of tendon suture and modified device for its external cutaneous fixation. Firm and safe junction of transplant with tendon parts of the deep flexor muscle allowed an early activation of the hand function and high efficacy of operative treatment

Oxygen non-stoichiometry and phase decomposition of double perovskite-like molybdates Sr2MMoO6-delta, where M = Mn, Co, and Ni

The thermodynamic stability borders and variations of oxygen non-stoichiometry in the perovskite-like molybdates Sr2MMoO6–δ, where M = Mn, Co, and Ni, are studied by using coulometric titration measurements. The data obtained are consistent with the reductive decomposition of Sr2NiMoO6–δ and Sr2CoMoO6–δ at small deviations of oxygen content 6–δ from its stoichiometric value. The manganite Sr2MnMoO6–δ exhibits considerably wider variations of δ at temperatures 1023 – 1223 K and oxygen pressures of 10–8 – 10–5 atm. The increase of the pressure results in Sr2MnMoO6–δ oxidative decomposition to SrMoO4 and Sr2Mn2O5 followed by oxidation of Sr2Mn2O5 to SrMnO3. The estimates based on density functional theory (DFT) are used to rationalize the results obtained.This work was carried out under support of government assignment for the ISSC UB RAS (theme № AAAA-A19-119031890026-6). DFT calculations were performed on the URAN cluster at the IMM UB RAS.Peer reviewe

Reassessment of thermochemical energy storage in perovskite-like manganites at comparative studies of RP SrCa3Mn3O10-d vs. orthorhombic Sr0.25Ca0.75MnO3-d

The structural stability, thermal expansion, oxygen exchange thermodynamics, and thermochemical storage (TCS) capacity of perovskite-like Sr0.25Ca0.75MnO3-δ and Ruddlesden-Popper SrCa3Mn3O10-δ manganites are studied by the combined use of experimental techniques, thermodynamic modeling of the defect formation reactions, and energy calculations utilizing density functional theory (DFT). It is argued that conservative estimates of the storage capacity can be made by the use of the Dulong-Petit limit for high-temperature heat capacity and oxygen partial enthalpy independent of both temperature and oxygen content. The respectively recalculated literature data and the obtained results show that the thermodynamic limit for the TCS capacity (~800 kJ/kg) of Sr0.25Ca0.75MnO3-δ is one of the highest at thermal cycling within the oxygen partial pressure range of 10 −4–0.21 atm. At the same time, the storage capacity of SrCa3Mn3O10-δ achieves only about 600 kJ/kg. The TCS cycling tests demonstrate the stability of SrCa3Mn3O10-δ while a decline in the energy storage capacity is observed for Sr0.25Ca0.75MnO3-δ. According to the EDX analysis, this effect may reflect surface degradation of Sr0.25Ca0.75MnO3-δ. The energy storage capacities of SrCa3Mn3O10-δ and Sr0.25Ca0.75MnO3-δ decrease to 510 and 560 kJ/kg, respectively, because of the rather sluggish reduction kinetics. It is concluded that further improvement of manganites as energy storage materials can be achieved using new doping strategies.This work was carried out under support of the state programs № АААА-А19-119031890026-6 and № АААА-А19-119110190048-7. Part of the DFT calculations were performed on the URAN cluster at the Institute of Mathematics and Mechanics, UB RAS.Peer reviewe