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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Fomin S. V., Muzalevskiy K. V.
Заглавие : A dielectric model for frozen mineral soils at a frequency of 435 MHz
Место публикации : Remote Sens. Lett. - 2021. - Vol. 12, Is. 9. - P.944-950. - ISSN 2150704X (ISSN), DOI 10.1080/2150704X.2021.1947537
Примечания : Cited References: 16. - This work was supported by the state assignment of the Ministry of Science and Higher Education of the Russian Federation [project No. 0287-2021-0034]
Аннотация: A single frequency refractive mixing dielectric model at 435 MHz for frozen mineral soils is proposed. The model was created based on the laboratory dielectric measurements of three soil samples in the ranges of soil moisture from 0.01cm3 cm−3 to 0.42cm3 cm−3, temperature from– 30°C to– 1°C, clay content (by weight) from 9.1% to 41.3%. Coefficient of determination R2 and root mean square error (RMSE) predicted by the model and measured values for real () and imaginary () part of the complex relative permittivity (CRP) are = 0.988 (= 0.323) and = 0.987 (= 0.100). Compared to well-known spectroscopic models, this model is simpler in practical engineering use. The input parameters of the model are the volumetric soil moisture, temperature and the content of the clay fraction. The output parameters are the real and imaginary parts of the CRP. The created model may be used to develop new remote sensing retrieval algorithms of temperature, the content of unfrozen water and ice in the root zone of frozen soils for northern regions.ε 'ε ''R2ε 'RMSEε 'R2ε ''RMSEε ''
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Muzalevskiy K. V.
Заглавие : A new method for remote sensing of moisture profiles in the arable layer at three frequencies; experimental case study
Место публикации : Int. J. Remote Sens. - 2021. - Vol. 42, Is. 7. - P.2377-2390. - ISSN 01431161 (ISSN), DOI 10.1080/01431161.2020.1851795
Примечания : Cited References: 35. - This work was supported by the Russian Foundation for Basic Research (grant No. 18-05-00405) in part of the sensing depth investigation and retrieving soil moisture. The method of the formation of radio impulses was created in part of SB RAS project No. 0356-2019-0004
Аннотация: In this paper, the possibilities of remote sensing of moisture profiles in the arable layer were theoretically and experimentally studied based on the nadir measurements of reflection coefficients at three frequencies of 1.26 GHz, 796 MHz and 641 MHz. The reflection coefficients were measured by the impulse method during natural cycles of evaporation and moistening of an arable layer at the agricultural field being under steam, located at 56°05ʹN, 92°40ʹ E in the area of the Minino village, Krasnoyarsk region, the Russian Federation. The soil moisture profiles were retrieved in the course of solving the inverse problem, in which the reflection coefficients at different frequencies acted as an informative sign. The root-mean-square error and the determination coefficient (R 2) between retrieved and measured moisture values in the topsoil thickness of 0.15 m were 3.3% and 0.79, respectively. In the course of theoretical calculations, it was shown that in practice, it is impossible to predict the sensing depth of the arable layer without preliminary information on the form of moisture profile. Moreover, the sensing depth depends not only on the form of soil moisture profile but also on frequency. In this regard, it is impossible to correlate the effective soil moisture, retrieved from single-frequency measurements of the reflection coefficient in the approximation of homogeneous topsoil, with the specific thickness of topsoil. The study shows the promise of developing multi-frequency radar systems for remote sensing of soil moisture profiles in the arable layer, the potential of which can be realized on lightweight unmanned area vehicle (UAV) platforms.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Drokin N. A., Shabanov V. F., Shepov V. N.
Заглавие : A study of the microwave dielectric permittivity of liquid crystals in electric and magnetic fields
Место публикации : Tech. Phys. - 1998. - Vol. 43, Is. 1. - P.105-109. - ISSN 1063-7842, DOI 10.1134/1.1258946
Примечания : Cited References: 8
Аннотация: A microwave detector based on a self-sustained oscillator circuit is proposed as a means to investigate the real and imaginary components of the dielectric permittivity of liquid crystals in external electric and magnetic fields. Results are given for measurements of a 500 MHz oscillator frequency for two types of nematic crystals, 5CBP and MBBA. Fundamental regularities are identified in the behavior of the microwave dielectric permittivity of samples in electric and magnetic fields. It is shown that the minimum of the high-frequency dielectric loss in liquid crystals correspond to a situation in which the long axes of the molecules are oriented parallel to the direction of the microwave electric field. (C) 1998 American Institute of Physics. [S1063-7842(98)02201-6].
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Epov M. I., Savin I. V., Mironov V. L.
Заглавие : A temperature-dependent dielectric model for water- and oil-containing rocks in the frequency range from 0.5 to 15 GHz
Место публикации : Russ. Geol. Geophys.: Elsevier Science BV, 2012. - Vol. 53, Is. 7. - P.698-703. - ISSN 1068-7971, DOI 10.1016/j.rgg.2012.05.008
Примечания : Cited References: 17
Предметные рубрики: MOIST SOILS
POLARIZATION PROCESSES
PERMITTIVITY METHOD
Ключевые слова (''Своб.индексиров.''): dielectric permittivity--effective conductivity--water-containing rocks--temperature-dependent dielectric model
Аннотация: Dielectric spectra of water-containing rocks forming a mineral framework of the oil-saturated bed (clay minerals amount to˂16%) were measured in the frequency range from 500 MHz to 15 GHz and in the temperature range from 20 to 80 °C. A physical model for computing spectra of the dielectric permittivity and effective conductivity of the studied rocks has been elaborated. Its input parameters are water (salt solution) content and temperature. The errors of the computed spectra relative to the measured ones are estimated.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Maximova O. A., Ovchinnikov S. G., Lyashchenko S. A.
Заглавие : Analytical calculation of dielectric permittivity tensor from magneto-optical ellipsometry measurements
Коллективы : Government of the Russian Federation [075-15-2019-1886]
Место публикации : J. Phys. A: IOP PUBLISHING LTD, 2021. - Vol. 54, Is. 29. - Ст.295201. - ISSN 1751-8113, DOI 10.1088/1751-8121/abfe72. - ISSN 1751-8121(eISSN)
Примечания : Cited References: 24. - This study was supported by the Government of the Russian Federation (Agreement No. 075-15-2019-1886)
Предметные рубрики: FILMS
Аннотация: Magneto-optical ellipsometry combines ellipsometry and magneto-optical Kerr effect measurements which are two powerful techniques. The main difficulty is usually in data processing as a number of parameters should be extracted from measured ellipsometric (ψ, Δ) and magneto-ellipsometric (δψ, δΔ) parameters. Standard procedure of solving magneto-ellipsometry equations involves numerical calculations. In this paper we show that it is possible to find out all elements of dielectric permittivity tensor without numerical calculation methods. It means that the inverse problem of magneto-optical ellipsometry can be solved analytically in the case of expansion of magneto-ellipsometric parameters δψ and δΔ with respect to two small parameters. We present a full set of mathematical expressions that enable us to calculate complex refraction index and complex magneto-optical parameter of a sample from magneto-optical ellipsometry measurements, thereby obtaining diagonal and off-diagonal complex elements of dielectric permittivity tensor. This analytical approach can be used in case of the contribution from magnetism into reflection coefficients being small.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kuz'menko A. M., Mukhin A. A., Ivanov V. Y., Kadomtseva A. M., Lebedev S. P., Bezmaternykh L. N.
Заглавие : Antiferromagnetic Resonance and Dielectric Properties of Rare-earth Ferroborates in the Submillimeter Frequency Range
Место публикации : J. Exp. Theor. Phys.: MAIK NAUKA/INTERPERIODICA/SPRINGER, 2011. - Vol. 113, Is. 1. - P113-120. - ISSN 1063-7761, DOI 10.1134/S106377611105013X
Примечания : Cited References: 27. - This work was supported by the Russian Foundation for Basic Research, project no. 10-02-00846.
Предметные рубрики: GDFE3(BO3)(4)
SPECTROSCOPY
CRYSTAL
Ключевые слова (''Своб.индексиров.''): antiferromagnetic resonance--basic parameters--effective anisotropy constant--ferroborates--ferroics--ferromagnetic orderings--frequency ranges--magnetic interactions--magnetoresonance--millimeter frequency range--rare earth ions--submillimeters--antiferromagnetic materials--crystallography--erbium--europium--ferromagnetic resonance--ion exchange--magnetic anisotropy--magnetic devices--magnetic structure--permittivity--resonance--antiferromagnetism
Аннотация: The magnetoresonance and dielectric properties of a number of crystals of a new family of multiferroics, namely, rare-earth ferroborates RFe(3)(BO(3))(4) (R = Y, Eu, Pr, Tb, Tb(0.25)Er(0.75)), are studied in the submillimeter frequency range (nu = 3-20 cm(-1)). Ferroborates with R = Y, Tb, and Eu exhibit permittivity jumps at temperatures of 375, 198, and 58 K, respectively, which are caused by the R32 - P3(1)2(1) phase transition. Antiferromagnetic resonance (AFMR) modes in the subsystem of Fe(3+) ions are detected in the range of antiferromagnetic ordering (T T(N)
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Muzalevskiy K. V., Zeyliger, Anatoly
Заглавие : Application of Sentinel-1B polarimetric observations to soil moisture retrieval using neural networks: Case study for bare Siberian chernozem soil
Коллективы : Russian Foundation for Basic ResearchRussian Foundation for Basic Research (RFBR) [19-29-05261 mk]; Ministry of Science and Higher Education of the Russian Federation [0287-2021-0034]
Место публикации : Remote Sens. - 2021. - Vol. 13, Is. 17. - Ст.3480. - ISSN 2072-4292(eISSN), DOI 10.3390/rs13173480
Примечания : Cited References: 21. - This work was supported by the Russian Foundation for Basic Research (grant No. 19-29-05261 mk). The field experiment and EC-5 Decagon sensor calibration in laboratory conditions were carried out with the support of Ministry of Science and Higher Education of the Russian Federation, project No. 0287-2021-0034 (basic state assignment)
Предметные рубрики: SURFACE
MODEL
PARAMETERS
ROUGHNESS
INVERSION
DUBOIS
IEM
OH
Аннотация: Sentinel-1 is currently the only synthetic-aperture radar, which radar measurements of the earth’s surface to be carried out, regardless of weather conditions, with high resolution up to 5–40 m and high periodicity from several to 12 days. Sentinel-1 creates a technological platform for the development of new globally remote sensing algorithms of soil moisture, not only for hydrological and climatic model applications, but also on a single field scale for individual farms in precision farming systems used. In this paper, the potential of soil moisture remote sensing using polarimetric Sentinel-1B backscattering observations was studied. As a test site, the fallow agricultural field with bare soil near the Minino village (56.0865°N, 92.6772°E), Krasnoyarsk region, the Russian Federation, was chosen. The relationship between the cross-polarized ratio, reflectivity, and the soil surface roughness established Oh used as a basis for developing the algorithm of soil moisture retrieval with neural networks (NNs) computational model. Two NNs is used as a universal regression technique to establish the relationship between scattering anisotropy, entropy and backscattering coefficients measured by the Sentinel-1B on the one hand and reflectivity on the other. Finally, the soil moisture was found from the soil reflectivity in solving the inverse problem using the Mironov dielectric model. During the field campaign from 21 May to 25 August 2020, it was shown that the proposed approach allows us to predict soil moisture values in the layer thickness of 0.00–0.05 m with the root-mean-square error and determination coefficient not worse than 3% and 0.726, respectively. The validity of the proposed approach needs additional verification on a wider dataset using soils of different textures, a wide range of variations in soil surface roughness, and moisture.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Udod L. V., Sitnikov M. N., Shestakov N. P.
Заглавие : Bi2(Sn0.95Cr0.05)2O7: Structure, IR spectra, and dielectric properties
Место публикации : Ceram. Int.: Elsevier, 2016. - Vol. 42, Is. 4. - P.5177-5183. - ISSN 02728842 (ISSN), DOI 10.1016/j.ceramint.2015.12.040
Примечания : Cited References: 45. - This work was supported by the Russian Foundation for Basic Research Projects no. 15-42-04099 r_siberia_a, Siberian Branch of Science and NAS of Belarus “Electronic and magnetic phase transitions in materials with magnetoelectric affect” and government work no. 114090470016.
Предметные рубрики: BISMUTH PYROSTANNATE
PYROCHLORE STRUCTURE
MAGNETIC-PROPERTIES
PARTIAL OXIDATION
HIGH-TEMPERATURE
X-RAY
Bi2Sn2O7
SUBSTITUTION
CATALYSTS
DIFFRACTION
Ключевые слова (''Своб.индексиров.''): bismuth pyrostannate--infrared absorption spectra--structural transition--permittivity--debye model
Аннотация: Infrared absorption spectra of the bismuth pyrostannate Bi2(Sn0.95Cr0.05)2O7 were investigated in the frequency range 350-1100 cm-1 at temperatures of 110-525 K. Four frequency regions with split absorption lines are distinguished. Softening of frequencies at the structural transitions was observed. The maxima of permittivity measured in the frequency range 1-200 kHz at temperatures 100-400 K were determined. It was found that the magnetic susceptibility changes its sign in the low-temperature region. The correlation between anomalies in the magnetic susceptibility, permittivity, and absorption line intensity was established. Softening of frequencies is explained by the variation in the coefficient of thermal expansion of the lattice. The temperature behavior of permittivity is described using the Debye model. © 2015 Elsevier Ltd and Techna Group S.r.l.
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Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bulgakov E. N., Sadreev A. F.
Заглавие : Bound states in the continuum with high orbital angular momentum in a dielectric rod with periodically modulated permittivity
Коллективы : Ministry of Education and Science of Russian Federation [N 3.1845.2017]; RFBR [16-02-00314]
Место публикации : Phys. Rev. A: American Physical Society, 2017. - Vol. 96, Is. 1. - Ст.013841. - ISSN 2469-9926, DOI 10.1103/PhysRevA.96.013841. - ISSN 2469-9934(eISSN)
Примечания : Cited References:38. - We acknowledge discussions with D. N. Maksimov and A. S. Aleksandrovsky. This work was partially supported by Ministry of Education and Science of Russian Federation (State Contract No. N 3.1845.2017) and RFBR Grant No. 16-02-00314.
Предметные рубрики: PHOTONIC CRYSTAL SLABS
LIGHT-CONE
RESONANCES
SPHERES
RADIATION
Аннотация: We report bound states in the radiation continuum (BICs) in a single infinitely long dielectric rod with periodically stepwise modulated permittivity alternating from ε1 to ε2. For ε2 = 1 in air the rod is equivalent to a stack of dielectric disks with permittivity ε1. Because of rotational and translational symmetries the BICs are classified by orbital angular momentum m and the Bloch wave vector beta directed along the rod. For m = 0 and β = 0 the symmetry protected BICs have definite polarization and occur in a wide range of the radius of the rod and the dielectric permittivities. More involved BICs with m ≠ 0, β = 0 exist only for a selected radius of the rod at a fixed dielectric constant. The existence of robust Bloch BICs with β ≠ 0, m = 0 is demonstrated. Asymptotic limits to a homogeneous rod and to very thin disks are also considered.
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10.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Aleksandrov K. S., Turchin P. P., Sorokin B. P., Karpovich A. A., Nefedov V. A.
Заглавие : Bulk acoustic waves propagation in Li2B4O7 piezoelectric crystals under the static uniaxial mechanical pressure
Коллективы : Annual frequency control symposium
Место публикации : Proceedings of the Annual IEEE International Frequency Control Symposium/ Annual frequency control symposium (54 ; 2000 ; Jun. ; 7-9 ; Kansas, MO). - 2000. - P.214-217. - ISBN 01616404
Примечания : Cited References: 8
Ключевые слова (''Своб.индексиров.''): acoustic wave transmission--acoustic wave velocity--elasticity--lithium compounds--mathematical models--permittivity--piezoelectricity--pressure effects--single crystals--electromechanical constants--piezoelectric crystal--piezoelectric materials
Аннотация: The influence of uniaxial mechanical stresses on bulk acoustic waves velocity in piezoelectric crystals Li2B4O7 has been investigated. Electromechanical constants have determined.
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11.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : ZINENKO V. I., FEDOROV A. S.
Заглавие : CALCULATION OF LONG-WAVELENGTH PHONON FREQUENCIES, OF DIELECTRIC PERMITTIVITY, AND B1-B2 PHASE-TRANSITIONS IN ALKALI-METAL HYDRIDES BY THE DENSITY-FUNCTIONAL TECHNIQUE
Место публикации : Fiz. Tverd. Tela: MEZHDUNARODNAYA KNIGA, 1994. - Vol. 36, Is. 5. - P1357-1365. - ISSN 0367-3294
Примечания : Cited References: 17
Предметные рубрики: PRESSURE
ENERGY
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12.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aleksandrova I. P., Seryukova I. V., Zherebtsova L. I.
Заглавие : Dielectric permittivity behavior at nonequilibrium processes in nh4hseo4 ferroelectrics
Место публикации : Fiz. Tverd. Tela. - 1985. - Vol. 27, Is. 11. - P.3438-3441. - ISSN 0367-3294
Примечания : Cited References: 5
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13.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Bobrov P. P., Mironov V. L., Repin A. V.
Заглавие : Dielectric permittivity spectra of oil-water-saturated sandy-clayey rocks of different mineralogical compositions and relaxation properties of water in these rocks
Коллективы : RFBR [12-05-00502a, 14-05-00151a]
Место публикации : Russ. Geol. Geophys.: Elsevier Science, 2015. - Vol. 56, Is. 7. - P.1065-1073. - ISSN 1068-7971, DOI 10.1016/j.rgg.2015.06.007
Примечания : Cited References: 21. - This work was supported by RFBR (grant nos. 12-05-00502a and 14-05-00151a).
Предметные рубрики: MOIST SOILS
FREQUENCY
MODEL
TEMPERATURE
SALINITY
RANGE
GHZ
Ключевые слова (''Своб.индексиров.''): conductivity--dielectric permittivity--multifrequency dielectric relaxation--oil-bearing deposits--sandy-clayey rocks
Аннотация: Experimental measurements of the dielectric permittivity and equivalent conductivity of sandy-clayey samples (a mixture of river sand with bentonite or kaolin) saturated with salt-solution-diesel-fuel emulsions were performed in the frequency range from 10 kHz to 1 GHz at temperatures of 25-65 °C. It is shown that when the content of the salt solution in the saturating fluid does not exceed 10%, the dielectric permittivity in the frequency range from 1 MHz to 1 GHz depends little on the mineral composition of the sample and on the concentration of the saturating solution. When the portion of water is 33.3% or higher, increasing the concentration of the salt solution leads to an increase in the equivalent conductivity and the real part of the complex dielectric permittivity. Using the refractive model of the complex dielectric permittivity, we have estimated the dielectric properties of bound water, which depend on temperature and the type of clay (bentonite or kaolin) in the sand-clay mixture but are independent of the water saturation and the amount of clay in the sample.
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14.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Volkov N. V., Eremin E. V., Sablina K. A., Sapronova N. V.
Заглавие : Dielectric properties of a mixed-valence Pb3Mn7O15 manganese oxide
Коллективы :
Разночтения заглавия :авие SCOPUS: Dielectric properties of a mixed-valence Pb3Mn7O 15 manganese oxide
Место публикации : J. Phys.: Condens. Matter: IOP PUBLISHING LTD, 2010. - Vol. 22, Is. 37. - Ст.375901. - ISSN 0953-8984, DOI 10.1088/0953-8984/22/37/375901
Примечания : Cited References: 14. - This study was supported by the Russian Foundation for Basic Research 'Siberia', project No. 09-02-98003, and the Siberian Branch of the Russian Academy of Sciences, integration project No. 101.
Ключевые слова (''Своб.индексиров.''): cation--lead--manganese derivative--oxide--article--chemical model--chemistry--crystallization--electric conductivity--electronics--methodology--temperature--cations--crystallization--electric conductivity--electronics--lead--manganese compounds--models, chemical--oxides--temperature--ac electric field--analysis of resistivity--carrier hopping--charge ordering--complex dielectric constant--crystal site--debye models--dielectric constants--dielectric spectra--frequency windows--lattice sites--low frequency--manganese ions--mixed valence--mixed valence state--relaxation behaviors--temperature range--electric fields--manganese--manganese oxide--permittivity--single crystals--crystal symmetry
Аннотация: We investigated the low-frequency dielectric properties of a Pb3Mn7O15 single crystal with manganese ions in the mixed-valence state (Mn3+/Mn4+). Dielectric relaxation was found in the frequency window from 20 to 100 kHz in the temperature range 110-180 K. The dielectric spectra of the crystal were analyzed using a Debye model. Estimations made within the model and analysis of resistivity data suggest that the relaxation behavior of the dielectric constant is related to polaronic charge carrier hopping. Around 250 K, charge ordering occurs in the crystal when the Mn3+ and Mn4+ ions are arranged in a specific order among the crystal sites. With a decrease in temperature, an ac electric field can induce a charge hop between the equivalent lattice sites available, related to crystal symmetry. This hopping is equivalent to the reorientation of an electric dipole that yields Debye-type behavior of the complex dielectric constant. The observed anisotropy in the behavior of the dielectric properties and resistivity can be attributed to a pronounced two-dimensional character of the crystal structure.
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15.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Aplesnin S. S., Udod L. V., Sitnikov M. N., Kretinin V. V., Molokeev M. S., Mironova-Ulmane N.
Заглавие : Dipole glass in chromium-substituted bismuth pyrostannate
Коллективы : Russian Foundation for Basic Research [N 18-52-00009 Bel_a, 18-32-00079 mol_a, 3.5743.2017/6.7]
Место публикации : Mater. Res. Express. - 2018. - Vol. 5, Is. 11. - Ст.115202. - ISSN 2053-1591, DOI 10.1088/2053-1591/aaddd9
Примечания : Cited References: 33. - This study was supported by the Russian Foundation for Basic Research project N 18-52-00009 Bel_a, No 18-32-00079 mol_a, the state order No 3.5743.2017/6.7.
Предметные рубрики: BI4TI3O12 THIN-FILMS
NEUTRON-DIFFRACTION
RAMAN-SPECTROSCOPY
BI2SN2O7
Ключевые слова (''Своб.индексиров.''): dipole glass--permittivity--polarization--raman scattering spectra--structural transition
Аннотация: To establish the existence of dipole glass in the chromium-substituted bismuth pyrostannate solid solutions, the frequency and temperature dependences of the permittivity have been measured in the temperature range of 300–750 K. The field and dynamic dependences of polarization in the temperature range of 80–550 K have been determined. Using the Raman scattering spectra, the absence of inversion center has been established. The maximum of electrical resistance has been found in the vicinity of the dipole moment freezing point. The carrier type has been determined from the thermopower data. The polarization relaxation is shown to be nonexponential. The experimental data are explained within the model of dipole glass in the α- phase and the model of charged crystalline domain walls with the electron-polarization relaxation mechanism above the α–β structural transition.
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16.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Flerov I. N., Gorev M. V., Fokina V. D., Bovina A. F., Bogdanov E. V., Pogoreltsev E. I., Laptash N. M.
Заглавие : Disorder and phase transitions in oxyfluoride (NH4)(3)Ta(O-2)(2)F-4
Место публикации : J. Fluor. Chem. - 2011. - Vol. 132, Is. 10. - P.713-718. - ISSN 0022-1139, DOI 10.1016/j.jfluchem.2011.05.012
Примечания : Cited Reference Count: 19. - Гранты: This work was supported by the Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation (NSh-4645.2010.2).Финансирующая организация: Council on Grants from the President of the Russian Federation for the Support of Leading Scientific Schools of the Russian Federation [NSh-4645.2010.2]
Предметные рубрики: HEAT-CAPACITY
COMPLEXES
RB2KTIOF5
FLUORIDES
CRYOLITE
Ключевые слова (''Своб.индексиров.''): cubic oxyfluorides--structural disorder--phase transitions--entropy--permittivity--pressure effect--cubic oxyfluorides--entropy--permittivity--phase transitions--pressure effect--structural disorder
Аннотация: Calorimetric, X-ray, dielectric and DTA under pressure measurements have been performed on oxyfluoride (NH4)(3)Ta(O-2)(2)F-4. The succession of nonferroelectric phase transitions was found associated with the order-disorder processes. The comparative analysis tantalate with related niobate has revealed the important role of the central atom in the physical properties behavior, mechanism of structural distortions and barocaloric effect in oxyfluorides with the eight-coordinated anionic polyhedra. (C) 2011 Elsevier By. All rights reserved.
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17.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Mikhaleva E. A., Flerov I. N., Kartashev A. V., Gorev M. V., Molokeev M. S., Bogdanov E. V., Bondarev V. S., Korotkov L. N., Rysiakiewicz-Pasek E.
Заглавие : Effect of restricted geometry and external pressure on the phase transitions in ammonium hydrogen sulfate confined in a nanoporous glass matrix
Место публикации : J. Mater. Sci. - 2018. - Vol. 53, Is. 15. - P.12132–12144. - ISSN 00222461 (ISSN), DOI 10.1007/s10853-018-2467-1
Примечания : Cited References: 44. - The reported study was funded by Russian Foundation for Basic Research (RFBR) according to the Research Project No. 16-32-00092 mol_a.
Ключевые слова (''Своб.индексиров.''): hydraulics--hydrostatic pressure--permittivity--pore size--specific heat--sulfur compounds--thermal expansion
Аннотация: A study of heat capacity, thermal dilatation, susceptibility to hydrostatic pressure, permittivity and polarization loops was carried out on NH4HSO4–porous glass nanocomposites (AHS + PG) as well as empty glass matrices. The formation of dendrite clusters of AHS with a size, dcryst, exceeding the pore size was found. An insignificant anisotropy of thermal expansion of AHS + PG showing statistically uniform distribution of AHS with random orientations of nanocrystallites over the matrix was observed. The effect of internal and external pressures on thermal properties and permittivity was studied. At the phase transition P-1 ↔ Pc, a strongly nonlinear decrease in the entropy ΔS2 and volume strain (ΔV/V)T2 was observed with decreasing dcryst. The linear change in temperatures of both phase transitions P-1 ↔ Pc ↔ P21/c under hydrostatic pressure is accompanied by the expansion of the temperature range of existence of the ferroelectric phase Pc, while this interval narrows as dcryst decreases.
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18.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Muzalevskiy K. V., Lukin Y. I.
Заглавие : Effects of organo-mineral structure of arctic topsoil on the own thermal radiation in the L-band
Коллективы : International Siberian Conference on Control and Communications
Место публикации : Int. Sib. Conf. on Control and Communicat. (SIBCON 2015): Proceedings: IEEE-Institute Electrical and Electronics Engineers, 2015. - ISBN 9781479971022 (ISBN), DOI 10.1109/SIBCON.2015.7147152
Ключевые слова (''Своб.индексиров.''): artic tundra--mineral soil--organic soil--permafrost--smos--soil temperature--atmospheric humidity--balloons--heat radiation--landforms--luminance--minerals--permafrost--permittivity--radiation effects--soils--temperature--artic tundra--mineral soils--organic soil--smos--soil temperature--soil surveys
Аннотация: In this paper, the influence of organic-mineral Arctic tundra soils on own thermal radiation in the L-band was theoretically investigated. For modeling of brightness temperature there were used semi-empirical L-band Microwave Emission of the Biosphere (L-MEB) model. An integral part of this model is permittivity models of tundra organic and mineral soils, which links the brightness temperature with moisture, temperature and density of soil. The permittivity models were developed based on the measurements of the organic rich and mineral soil samples collected at the Vaskiny Dachi weather station test-site in Yamal peninsular. As a result, the potential error of soil temperature retrieval in case of layered and homogeneous organic-mineral soil are shown based on simulated brightness temperature at 1.4 GHz. © 2015 IEEE.
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19.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Markevich I. A., Selyutin G. E., Drokin N. A., Selyutin A. G.
Заглавие : Electrical and mechanical properties of the high-permittivity ultra-high-molecular-weight polyethylene-based composite modified by carbon nanotubes
Место публикации : Tech. Phys. - 2020. - Vol. 65, Is. 7. - P.1106-1113. - ISSN 10637842 (ISSN), DOI 10.1134/S1063784220070129
Примечания : Cited References: 39
Аннотация: A composite based on ultra-high-molecular-weight polyethylene (UHMWPE) added with 1 wt % of multiwalled carbon nanotubes (MWCNTs) with a high permittivity (ε = 4.5) and a low dielectric loss (tanδ = 10–2) in the frequency range from 100 Hz to 100 MHz has been synthesized, and its main mechanical characteristics have been studied. The material has a low (22 MPa) breaking strength, a high (700%) tensile elongation, and an abrasion resistance higher than that of pure UHMWPE by 37%. It is shown using the X-ray diffraction and differential scanning calorimetry data that the changes in the mechanical properties of the composite are related to the changes in the polymer matrix structure under the action of the high-intensity ultrasonic radiation used for embedding MWCNTs into the polymer.
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20.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Belyaev B. A., Tyurnev V. V.
Заглавие : Electrodynamic calculation of effective electromagnetic parameters of a dielectric medium with metallic nanoparticles of a given size
Место публикации : J. Exp. Theor. Phys. - 2018. - Vol. 127, Is. 4. - P.608-619. - ISSN 10637761 (ISSN), DOI 10.1134/S1063776118100114
Примечания : Cited References: 31. - This work was supported by the Ministry of Education and Science of the Russian Federation (contract no. 14.575.21.0142; unique identifier of the project is RFMEFI57517X0142).
Ключевые слова (''Своб.индексиров.''): electromagnetic fields--magnetic susceptibility--metals--nanoparticles--natural frequencies--permittivity
Аннотация: The frequency dependence of the effective complex permittivity and effective complex permeability of a heterostructure based on a dielectric medium containing metallic nanoparticles of spherical shape is calculated by an original method. In contrast to the Bruggeman [21] and the Maxwell Garnett [17] approaches, which use the quasi-static approximation in calculations, a nonuniform distribution of electromagnetic fields inside metallic particles is calculated, which allows the analysis of the electromagnetic parameters of the heterostructure not only as a function of frequency but also as a function of the nanoparticle size. It is shown that the plasmon resonant frequency decreases with increasing both the size and the concentration of particles in the heterostructure. It is also shown that a dielectric medium containing nonmagnetic metallic nanoparticles exhibits diamagnetic properties. In this case, the position of the maximum on the frequency dependence of the imaginary part of the magnetic susceptibility coincides with the relaxation frequency of charge carriers. The calculated spectra of the real and imaginary components of the permittivity of the heterostructure with a size of metallic particles less than 10 nm are in good agreement with Bruggeman calculations; however, the agreement with Maxwell Garnett calculations is observed only at nanoparticle concentrations lower than 10–6.
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