Physics of the Solid State最新文献

{"title":"Influence of High Pressures on the Solidification of the Al86Ni6Co4Gd2Tb2 Liquid Alloy","authors":"S. G. Menshikova,&nbsp;V. V. Brazhkin,&nbsp;A. S. Danilova","doi":"10.1134/S1063783422090049","DOIUrl":"10.1134/S1063783422090049","url":null,"abstract":"<p>The purpose of this work is to study the possibility of the formation of new phases in the Al₈₆-Ni₆Co₄Gd₂Tb₂ alloy upon rapid solidification of its high-temperature melt under high pressure. Samples for research were obtained under high pressures of 3, 5, and 7 GPa in a high-pressure chamber of the “toroid” type. The chamber consists of flat hard alloy anvils pressed into steel rings. Alget stone was used as a pressure-transmitting medium. Heating and melting of the sample was carried out by passing an alternating current through the sample placed in a hexagonal boron nitride crucible. High pressure punches served as current leads. The temperature value was calculated on the basis of the thyristor readings, according to the current power. Cooling of the melts was carried out at a rate of 1000 deg/s, the temperature of the melt before quenching was 1500°C. Experimental scheme: pressure setting → pulse heating → holding at a set pressure and temperature → cooling without depressurization to room temperature → high pressure reduction to atmospheric. The microstructure of the samples of the alloy of the eutectic composition Al₈₆Ni₆Co₄Gd₂Tb₂, obtained depending on the quenching temperature (1500°C) and high pressure (3, 5, and 7 GPa), has been investigated by the methods of X-ray diffraction analysis, optical and electron microscopy. Cooling rate 1000 deg/s. Due to the combination of a high solidification rate and mechanical compaction under high pressure, samples of an alloy of the composition Al₈₆Ni₆Co₄Gd₂Tb₂ with a fine structure and high density were obtained. At pressures of 5–7 GPa, the formation of new phases was noted in the alloy: Al₃(Gd/Tb)* (of the Al₃U type), with a primitive cube structure (<i>cP</i>4/2) with a lattice parameter <i>a</i> = 4.285 ± 0.002 Å and Al₈(Ni/Co)₄Gd* (of the Al₈Cr₄Gd type) with a tetragonal structure (<i>tI</i>26/1) with parameters <i>a</i> = 8.906 ± 0.003 Å and <i>c</i> = 5.150 ± 0.003 Å. Studies have shown that the average microhardness of a sample obtained, in particular, under a pressure of 7 GPa, is high (~1700 MPa) due to solid solution and precipitation hardening. This is almost 2 times higher than in the original sample. The results obtained show the fundamental possibility of using the method of solidification of the melt under high pressure to change the level of properties of aluminum alloys used in industry without changing their chemical composition by modifying the structure and changing the composition of the structural components of the sample.</p>","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"4720793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Simulating 2D-Diffraction Patterns of Model Gallium Arsenide Whisker Crystals","authors":"Sharkov M.D., Prasolov N.D., Levin A.A., Brunkov P.N.","doi":"10.21883/pss.2023.01.54981.493","DOIUrl":"https://doi.org/10.21883/pss.2023.01.54981.493","url":null,"abstract":"A set of GaAs whisker crystallites in the shape of hexagonal prism with the axisalong the [111] direction have been modeled as well as constructions consisting of such prisms. For these model samples XRD patterns have been calculated. Basing on the calculated XRD pattern analysis, a fitting configuration of prismatic fragments has been built for an atomic array obtained with the help of applying molecular dynamics techniques to the initial model prismatic GaAs crystallite. Keywords: whiskers, XRD pattern simulation, AIIIBV semiconductors, gallium arsenide.","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74155410","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Study of magnetic iron oxide nanoparticles coated with silicon oxide by ferromagnetic method","authors":"Vazhenina I.G., Stolyar S.V., Tyumentseva A.V., Volochaev M.N., Iskhakov R.S., Komogortsev S.V., Pyankov V. F., Nikolaeva E.D.","doi":"10.21883/pss.2023.06.56095.01h","DOIUrl":"https://doi.org/10.21883/pss.2023.06.56095.01h","url":null,"abstract":"Magnetic nanoparticles of magnetite with a size of ~8 nm synthesized with a different type of coating were studied by ferromagnetic resonance in the temperature range from 7 to 300 K. The features of the experimental temperature dependences of the parameters of the ferromagnetic resonance curve (the magnitude of the resonant field, line width and intensity) and their approximation allowed us to estimate the values of characteristic temperatures. Firstly, the value of the Vervey temperature and the dependence of its value on the type of coating were determined. Secondly, the temperature of transition of nanoparticles to the superparamagnetic state (blocking temperature) and the temperature range within which the magnetic structure of the outer shell of the magnetic nanoparticle is in the spin glass state are established Keywords: iron oxide nanoparticles, ferromagnetic resonance, superparamagnetism, blocking temperature.","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74487293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Topological bands in metals with helical magnetic order","authors":"Kudasov Yu. B.","doi":"10.21883/pss.2023.06.56098.04h","DOIUrl":"https://doi.org/10.21883/pss.2023.06.56098.04h","url":null,"abstract":"The effect of a helicoidal magnetic field on the dispersion of conduction electrons in one- and two-dimensional systems is investigated. In a helicoidal periodic magnetic field, there is a special symmetry with respect to the reversal of time, which leads to the peculiarities of the band structure. Using an example of a one-dimensional model system, the topological properties of the band structure in an effective magnetic field corresponding to the 120o-ordering are investigated. In PdCrO2, the 120o magnetic ordering of the dielectric layers of CrO2 creates an unusual spin structure of the Fermi surface in conducting palladium layers. In this case, the umklapp scattering of mobile charge carriers is strongly suppressed, which leads to abnormally high conductivity at low temperatures observed experimentally. Keywords: Helicoidal ordering, Time-reversal symmetry, Band structure, Charge carriers scattering, Metallic delafossites, PdCrO3.","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74321959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ag and Pb diffusion on Ge(111)-3x2sqrt(3)sqrtSn surface","authors":"Dolbak A. E","doi":"10.21883/pss.2023.01.54988.479","DOIUrl":"https://doi.org/10.21883/pss.2023.01.54988.479","url":null,"abstract":"Ag and Pb diffusion on Ge(111)-3x2sqrt(3)sqrtSn surface has been studied by Auger electron spectroscopy and low energy electron diffraction. The mechanism of diffusion of atoms of these elements along the Ge(111)-3x2sqrt(3)sqrtSn surface is determined, and the temperature dependences of the diffusion coefficients are measured. The diffusion parameters of Ag along the Ge(111)-3x2sqrt(3)sqrtSn and Si(111)-2sqrt(3)sqrtSn surfaces are compared. Keywords: surface, surface diffusion, Ge(111), Ag, Pb, Sn.","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72382917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Elastic Properties of B2-NiAl with W addition: A first-principles study","authors":"Ponomareva A. V.","doi":"10.21883/pss.2023.01.54968.477","DOIUrl":"https://doi.org/10.21883/pss.2023.01.54968.477","url":null,"abstract":"The effect of tungsten alloying on the elastic properties of B2-NiAl at low-temperature and high-temperature distribution of W atoms on sublattices. By means of the exact muffin-tin orbitals method in conjunction with the coherent potential approximation, the constants C11,C12,C44, Young's modulus E, shear modulus G, Cauchy pressure values, G/B ratios are calculated. Using phenomenological criteria of the correlation between ductility and elastic properties of solution phases, it has been shown that the addition of tungsten could yield improved ductility for B2-NiAl in both types of alloys. It is established that with the high-temperature distribution of W atoms on the Al sublattice, there is a loss of mechanical stability and a decrease in mechanical properties with increasing W concentration. In alloys with a low-temperature distribution of tungsten atoms between Al and Ni sites a unique combination of properties occurs: in addition to the ductility enhancement, a simultaneous increase of the elastic constants C44 and C11 and C11, shear modulus G, Young's modulus E with increasing W content is observed. The differences in the behavior of elastic constants in alloys with different types of tungsten distribution on NiAl sublattices are analyzed by calculating the density of electronic states. Keywords: NiAl, alloying elements, tungsten, elastic properties, ductility, first-principles calculations.","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75117592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ab initio simulations of dielectric and optical properties of ices I-=SUB=-h-=/SUB=-, I-=SUB=-II-=/SUB=- and lattices of hydrates sI, sH","authors":"Yunusov M. B., Khusnutdinoff R. M.","doi":"10.21883/pss.2023.02.55419.515","DOIUrl":"https://doi.org/10.21883/pss.2023.02.55419.515","url":null,"abstract":"The results of calculating the dielectric and optical characteristics of solid polymorphic phases of water ices Ih, III and lattices of hydrates sI, sH are presented. Static dielectric tensors εik and complex frequency-dependent tensors εik(ω) are calculated for these materials. It is shown that, in terms of optical properties, the crystal lattices Ih, III, and sH are uniaxial, the tensor components εxx(ω) and εyy(ω) coincide for them, and the hydrate lattice sI is isotropic. Based on the calculated frequency-dependent dielectric functions ε'ik(ω) and ε''ik(ω), important optical characteristics were obtained: reflection R(ω), absorption a(ω), loss function L(ω), refractive indices n(ω) and k(ω). Comparison of the dielectric and optical spectra of the sI and sH gratings with the known spectra for methane hydrate sI revealed a broadening of the spectra in the high-energy direction. For the unfilled hydrate sI, a reflection peak was found at an energy of 17.3 eV, the appearance of which is associated with a change in the electronic structure of the crystal in the absence of a methane molecule. Qualitative agreement is obtained between the reflection spectra R(ω) and the functions ε'ik(ω), ε''ik(ω), calculated by quantum mechanical simulation, with experimental spectroscopy data for hexagonal and amorphous ices. Keywords: ice, hydrate, dielectric tensor, optical functions.","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77533716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Formation of vertical graphene on surface of the gallium-arsenide structures","authors":"Zvonkov B. N., Antonov I. N., Vikhrova O. V., Danilov Yu. A., Dorokhin M. V., Dikareva N. V., Nezhdanov A. V., Temiryazeva M. P.","doi":"10.21883/pss.2023.04.56009.9","DOIUrl":"https://doi.org/10.21883/pss.2023.04.56009.9","url":null,"abstract":"The properties of carbon layers (C-layers) formed by thermal decomposition of CCl4 at temperatures of 600-700oC on the surface of gallium arsenide structures fabricated by MOC-hydride epitaxy on n+-GaAs (100) wafers have been studied. The surface morphology of the carbon layers was studied using atomic force microscopy. The structural and optical properties were studied using Raman spectroscopy and reflection spectroscopy. It has been found that in the case of a C-layer fabricated at a temperature of 650-700oC, the atomic force microscopy image demonstrates the presence of vertical carbon nanowalls (vertical graphene) located parallel to one of the [110] directions of the GaAs crystal lattice. The characteristics of the bands observed in the Raman spectra correspond to the parameters of the spectra of vertical graphene. The reflectivity coefficient of such carbon layers significantly decreases (diffuse reflection does not exceed 25% for a layer fabricated at 700oC) in the wavelength range from 0.19 to 1.8 μm. The presence of a significant \"absorbing\" ability makes the obtained carbon layers promising as a conducting contact in photosensitive semiconductor device structures, which is confirmed by preliminary results of studies of the current-voltage characteristics and spectral dependences of the photocurrent. Keywords: thermal decomposition of carbon tetrachloride, gallium arsenide, vertical graphene morphology.","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85751130","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dispersion of dielectric permittivity and electrical modulus in Ag-=SUB=-x-=/SUB=-HfS-=SUB=-2-=/SUB=- compounds with a layered structure","authors":"Pleshchev V. G.","doi":"10.21883/pss.2023.02.55404.520","DOIUrl":"https://doi.org/10.21883/pss.2023.02.55404.520","url":null,"abstract":"According to the impedance spectroscopy data, a significant frequency dispersion of the real and imaginary components of the permittivity was found in the intercalated AgxHfS2 samples. Using the modular formalism, the dielectric relaxation times were determined, which decrease in magnitude with an increase in the silver content in the samples. Their coincidence with the relaxation times determined from the frequency dependences of the imaginary parts of the complex impedance was shown. Keywords: Intercalates, impedance, hafnium disulfide, silver, dielectric permittivity, electrical module.","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80965109","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Determination of 2DEG parameters in LED heterostructures with three quantum wells In-=SUB=-x-=/SUB=-Ga-=SUB=-1-x-=/SUB=-N/GaN by terahertz time-domain spectroscopy (THz-TDs)","authors":"Burmistrov E. R., Avakyants L. P.","doi":"10.21883/pss.2023.02.55399.503","DOIUrl":"https://doi.org/10.21883/pss.2023.02.55399.503","url":null,"abstract":"Terahertz time-domain spectroscopy (THz-TDs) has been used to record the resonant frequencies of plasmon oscillations excited in samples of heterostructures with three InxGa1-xN/GaN quantum wells (QWs) by laser pulses with a duration of 130 fs in the temperature range from 90 to 170 K. Fast Fourier transform (FFT) of the time dependence of the electric field of THz-pulses made it possible to obtain the frequency spectra of the power and phase shift of THz-radiation, the interpretation of which made it possible to estimate the pulse relaxation time, mobility and effective mass of two-dimensional electron gas (2DEG) in the heterostructures. Using a series of frequency spectra of the power and phase shift of THz-radiation, the temperature dependences of the effective mass and relaxation time of the 2DEG pulse were obtained. Mobility value 2DEG obtained by the THz-TDs is in good agreement with the data of Hall measurements. Keywords: heterostructures, pulse relaxation time, 2DEG, terahertz radiation, terahertz spectroscopy.","PeriodicalId":731,"journal":{"name":"Physics of the Solid State","volume":null,"pages":null},"PeriodicalIF":0.6,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76738063","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}