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structural evolution-enabled BiFeO3 modulated by strontium doping with enhanced dielectric,optical and superparamagnetic properties by a modified sol-gel method

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Chinese Physics B 2023年第3期32卷 521-530页

作者： sharon v s veena Gopalan E Malini K A Department of Physics vimala College Thrissur-9 KeralaIndia

Multiferroic(BFO)nanoparticles doped with strontium with the general formula Bi1-xsrx FeO3(x=0,0.3,0.5,0.7)were synthesized using a modified sol-gel auto-combustion *** structural,electrical,optical,and magnetic properties of the samples are *** structural analysis,carried out using the x-ray powder diffraction technique,shows a structural transition from rhombohedral(R-3c)to cubic(Pm-3m)for the doping amount of strontium(sr)equal to x=*** analysis of the prepared samples were carried out using scanning electron microscopy(sEM).Frequency-dependent dielectric constant and ac conductivity were *** doped samples,with improved dielectric properties,can be used to fabricate different optoelectronic *** dielectric dispersion and broad relaxation were exhibited by all the ***–Cole plots were employed as an effective tool to study the dispersion parameters,namely,the optical dielectric constant,static dielectric constant,relaxation time,and spreading *** activation energy was calculated from the relaxation peaks and Cole–Cole plots,which were found to be compatible with each *** bandgap of the samples was calculated using diffuse reflectance spectral(DRs)*** and strong photoluminescence in the IR region was observed in the samples,similar to ZnO,which was reported for the first ***-temperature and low-temperature magnetization studies point towards the superparamagnetic nature of the samples,with an improvement in magnetic properties with *** antiferromagnetic behavior of bulk bismuth ferrite transforms to superparamagnetic in nature for both pure and sr-substituted bismuth ferrite nanoparticles due to the close dimensions of crystallite size with magnetic domains leading to the break-down of the frustrated spin cycloidal moment.

关键词： multiferroics sol-gel process x-ray spectra optical and dielectric properties

Main Directions and Recent Test Modeling Results of Lithium Capillary-Pore systems as Plasma Facing Components

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Plasma science and Technology 2004年第3期6卷 2291-2295页

作者： v.A.Evtikhin I.E.Lyublinski A.v.vertkov E.A.Azizov s.v.Mirnov v.B.Lazarev s.M.sotnikov v.M.safronov A.s.Prokhorov v.M.Korzhavin FsUE "Red star"-"Prana-Center" Co Moscow Russian FsUE TRINITI Troitsk Moscow region Russian Federation RF Ministry for Atomic Energy Moscow

At present the most promising principal solution of the divertor problemappears to be the use of liquid metals and primarily of lithium Capillary-Pore systems (CPs) as ofplasma facing materials. A solid CPs filled with liquid lithium will have a high resistance tosurface and volume damage because of neutron radiation effects, melting, splashing and thermalstress-induced cracking in steady state and during plasma transitions to provide the normaloperation of divertor target plates and first-wall protecting elements. These materials will not bethe sources of impurities inducing an increase of Z_(eff) and they will not be collected as dust inthe divertor area and in ducts. Experiments with lithium CPs under simulating conditions of plasmadisruption on a hydrogen plasma accelerator MK-200 [~ (10 - 15) MJ/m^2, ~ 50 μs] have beenperformed. The formation of a shielding layer of lithium plasma and the high stability of thesesystems have been shown. The new lithium limiter tests on an up-graded T-11M tokamak (plasma currentup to 100 kA, pulse length ~0.3 s) have been performed. sorption and desorption of plasma-forminggas, lithium emission into discharge, lithium erosion, deposited power of the limiter areinvestigated in these experiments. The first results of experiments are presented.

关键词： lithium divertor plasma facing material

Karite-diamond fossil:A new type of natural diamond

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Geoscience Frontiers 2020年第4期11卷 1163-1174页

作者： T.G.shumilova v.v.Ulyashev v.A.Kazakov s.I.Isaenko s.A.svetov s.Yu.Chazhengina N.s.Kovalchuk Institute of Geology of Komi scientific Centre of the Ural Branch of the Russian Academy of sciences Pervomayskaya St.54Syktyvkar167982Russia Hawaii Institute of Geophysics and Planetology University of Hawaii at Manoa1680 East-West RoadHonoluluHI96822USA ssC FsUE Keldysh Research Centre Onezhskaya8125438MoscowRussia Institute of Geology of the Karelian Research Centre of the Russian Academy of sciences Petrozavodsk11 Pushkinskaya StreetRussia

Impact diamond is one of perspective natural type of superhard carbon materials,forming huge resources sometimes,such as Popigai impact structure counting the largest diamond storage on the *** present,there are two known types of impact diamonds-after-graphitic and after-coal varieties formed from different carbon *** we present for the first time a new impact diamond type-diamond fossils,named by "karite",formed about 70 Ma from unmetamorphosed organics in the giant Kara impact crater(Pay-Khoy,Russia).A full complex of the diamond fossil characteristics is described proving its nature and phase *** is presented with supernanocrystalline diamond aggregates,nicely preserves tiny cell morphology and relict features of lignin and *** diamond fossils are spread widely through the Kara impactites,point to possible wider distribution of impact diamonds within large impact occurrences around the world,can be used for impact modeling,astrobiological and material studies.

关键词： Astroblemes Impact diamonds Fossils Diamond paramorphs Astrobiology

Cross-method Analysis of Corotation Radii Data set for spiral Galaxies

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Research in Astronomy and Astrophysics 2024年第7期24卷 95-110页

作者： v.s.Kostiuk A.A.Marchuk A.s.Gusev sternberg Astronomical Institute Lomonosov Moscow State UniversityUniversitetsky pr.13119234 MoscowRussia Central(Pulkovo)Astronomical Observatory Russian Academy of SciencesPulkovskoye chaussee 65/1196140 St.PetersburgRussia saint Petersburg state University Universitetsky pr.28198504 St.PetersburgRussia

A corotation radius is a key characteristic of disk galaxies that is essential to determine the angular speed of the spiral structureΩ_p,and therefore understand its *** the literature,there are plenty of methods to estimate this value,but do these measurements have any consistency?In this work,we collected a data set of corotation radius measurements for 547 galaxies,300 of which had at least two *** initial analysis reveals that most objects have rather inconsistent corotation radius ***,a significant fraction of galactic disks is distinguished by a large error coverage and almost uniform distribution of *** findings do not have any relation to spiral type,Hubble classification,or presence of a *** other reasons,obtained results could be explained by the transient nature of spirals in a considerable part of *** have made our collected data sample publicly available,and have demonstrated on one example how it could be useful for future research by investigating a winding time value for a sample of galaxies with possible multiple spiral arm patterns.

关键词： galaxies fundamental parameters-galaxies kinematics and dynamics-galaxies structure

Influence of alkali metal doping on surface properties and catalytic activity/selectivity of CaO catalysts in oxidative coupling of methane

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Journal of Natural Gas Chemistry 2008年第4期17卷 313-320页

作者： v.H.Rane s.T.Chaudhari v.R.Choudhary Chemical Engineering and Process Development Division National Chemical Laboratory

surface properties （viz. surface area, basicity/base strength distribution, and crystal phases） of alkali metal doped CaO （alkali metal/Ca= 0.1 and 0.4） catalysts and their catalytic activity/selectivity in oxidative coupling of methane （OCM） to higher hydrocarbons at different reaction conditions （viz. temperature, 700 and 750 ℃; CH4/O2 ratio, 4.0 and 8.0 and space velocity, 5140-20550 cm^3 ·g^-1·h^-1） have been investigated. The influence of catalyst calcination temperature on the activity/selectivity has also been investigated. The surface properties （viz. surface area, basicity/base strength distribution） and catalytic activity/selectivity of the alkali metal doped CaO catalysts are strongly influenced by the alkali metal promoter and its concentration in the alkali metal doped CaO catalysts. An addition of alkali metal promoter to CaO results in a large decrease in the surface area but a large increase in the surface basicity （strong basic sites） and the C2＋ selectivity and yield of the catalysts in the OCM process. The activity and selectivity are strongly influenced by the catalyst calcination temperature. No direct relationship between surface basicity and catalytic activity/selectivity has been observed. Among the alkali metal doped CaO catalysts, Na-CaO （Na/Ca = 0.1, before calcination） catalyst （calcined at 750 ℃）, showed best performance （C2＋ selectivity of 68.8% with 24.7% methane conversion）, whereas the poorest performance was shown by the Rb-CaO catalyst in the OCM process.

关键词： oxidative coupling of methane alkali metal doped CaO catalysts basicity/base strength distribution catalytic activity/selectivity

structure,magnetic and adsorption properties of novel FePt/h-BN heteromaterials

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Nano Research 2023年第1期16卷 1473-1481页

作者： Anton s.Konopatsky vladislava v.Kalinina Alena s.savchenko Denis.v.Leybo Ekaterina v.sukhanova viktor s.Baidyshev Zakhar I.Popov Andrey v.Bondarev Josef Polčák Dmitry v.shtansky National University of science and Technology(MIsIs) Leninskiy prospect 4Moscow119049Russia Emanuel Institute of Biochemical Physics RAs Kosygina 4Moscow119334Russia Katanov Khakas state University 90 Lenin pr.655017 AbakanRussia Plekhanov Russian University of Economics 36 Stremyanny per.Moscow 117997Russia Department of Control Engineering Faculty of Electrical EngineeringCzech Technical University in PragueTechnicka 2Prague 16627Czech Republic CEITEC-Central European Institute of Technology Brno University of TechnologyPurkyňova 123Brno 61200 BrnoCzech Republic

Nanomaterials with high specific surface area and high absorption capacity are attracting increased interest aimed at imparting the desired magnetic *** work is devoted to the study of the effect of heat treatment in a hydrogen atmosphere on the microstructure,adsorption and magnetic properties of heterogeneous FePt/h-BN *** via the polyol process,FePt nanoparticles(NPs)had a sizestributed over the surface of hexagonal boron nitride(h-BN)*** temperature-activated fcc→fct phase transformation in ultrafine FePt NPs has been well *** NPs act as active centers dissociating H2 molecules and transfer adsorbed hydrogen atoms to the *** functional theory(DFT)calculations also indicate that the h-BN substrate can absorb hydrogen adsorbed on the FePt *** hydrogen circulation in the FePt/h-BN system promoted the fcc→fct phase transformation and allowed to control the magnetic ***/h-BN nanomaterials also exhibited a high adsorption capacity with respect to various organic dyes.

关键词： FePt/h-BN nanomaterials polyol synthesis phase transformations magnetic properties adsorption

New Data on the Mineralogy of Chromite from the Nuggihalli schist Belt,Western Dharwar Craton,Karnataka,India:Petrogenetic Implications

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Acta Geologica sinica(English Edition) 2011年第1期85卷 107-115页

作者： Perumala v.s.RAJU Elapavalooru v.s.s.K.BABU Roland K.W.MERKLE National Geophysical Research Institute Hyderabad India(Council of Scientific and Industrial Research) Department of Geology University of Pretoria PretoriaSouth Africa

The occurrence of rhythmic layering of chromite and host serpentinites in the deformed layered igneous complexes has been noticed in the Nuggihalli schist belt （NsB） in the western Dharwar craton, Karnataka, south India. For this study, the chromitite rock samples were collected from Jambur, Tagadur, Bhakatarhalli, Ranganbetta and Byrapur in the NsB. Petrography and ore microscopic studies on chromite show intense cataclasis and alteration to ferritchromite. The ferritchromite compositions are characterized by higher Cr number （Cr/[Cr＋AI]）（0.68-0.98） and lower Mg number （Mg/[Mg＋Fe]）（0.33-0.82） ratios in ferritchromite compared to that of parent chromite. The formation process for the ferritchromite is thought to be related to the exchange of Mg, AI, Cr, and Fe between the chromite, surrounding silicates （serpentines, chlorites）, and fluid during serpentinization.

关键词： chromite ferritchromite Nuggihalli schist belt Dharwar Craton India

Influence of the safety factor profile on the particle and heat transport in the Globus-M spherical tokamak

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Plasma science and Technology 2019年第11期21卷 1-6页

作者： A YU TELNOvA G s KURsKIEv E O KIsELEv N N BAKHAREv v K GUsEv N A KHROMOv s YU MEDvEDEv v B MIINAEv I v MIROsHNIKOv M I PATROv Yu v PETROv N v sAKHAROv A D sLADKOMEDOvA P B sHCHEGOLEv v v sOLOKHA v A TOKAREv s YU TOLsTYAKOv E A TUKHMENEvA Ioffe Institute Saint-Petersburg 194021Russia Keldysh Institute Russian Academy of SciencesMoscow 125047Russia NRC'Kurchatov Institute’ Moscow 123098Russia

The advanced tokamak scenario is a promising operation scenario for ITER and fusion neutron *** this scenario the minimum value of the safety factor in the center of the plasma exceeds *** the compact spherical tokamak Globus-M,the formation of such conditions is possible with neutral beam injection at the current ramp-up *** to the slower diffusion of current inside the plasma,a zone is formed with reduced heat and particle transport across the magnetic field,which affects the temperature and density profiles of the *** leads to the peaked density profile formation and improvement of the energy confinement *** achieve a high fraction of the bootstrap current,it is necessary to increase the plasma *** the same time,the maximum allowable pressure is limited to the normalized beta limit.

关键词： advanced tokamak mode transport analysis internal transport barriers

Electrochemical synthesis of boron-containing coatings on Mg alloy for thermal neutron shielding

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Journal of Magnesium and Alloys 2023年第10期11卷 3779-3789页

作者： K.v.Nadaraia s.N.suchkov N.s.Markin I.M.Imshinetskiy s.I.Ivannikov D.v.Mashtalyar A.Yu.Ustinov s.L.sinebryukhov s.v.Gnedenkov Institute of Chemistry FEB RAs 159 Pr.100-Letiya VladivostokaVladivostok 690022Russia

The work provides the results of the one-step formation of boron-containing coatings on an Mg–Mn–Ce alloy by plasma electrolytic oxidation. The results of studies of the composition, structure and morphology of heteroxide coatings are presented. It was established that the boron is contained in the coating mainly in the form of B or B_(2)O_(3). The introduction of B changes the color of coatings, and also helps to increase their porosity. The method of determining the full cross section of the interaction of thermal neutron absorption efficiency by samples material using the installation of neutron-activation analysis based on ^(252)Cf was developed. It was shown that the introduction of boron into the formed coatings allows to increase the macroscopic cross-section of the interaction of samples with thermal neutrons by 3.8 times. This effect opens the potential for the use of synthesized material in the field of nuclear technologies and aerospace industry.

关键词： Plasma electrolytic oxidation Boron Neutron capture Neutron shielding Protective coatings