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1.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Gamzatov A. G., Koshkid'ko Y. S., Freitas D. C., Moshkina E. M., Bezmaternykh L. N., Aliev A. M., Yu, S-C, Phan M. H.
Заглавие : Anisotropic magnetocaloric properties of the ludwigite single crystal Cu2MnBO5
Коллективы : Russian Science FoundationRussian Science Foundation (RSF) [18-12-00415]; Ministry of Science of the Russian Federation [AAAA-A17-117021310366-5]
Место публикации : Appl. Phys. Lett. - 2020. - Vol. 116, Is. 23. - Ст.232403. - ISSN 0003-6951, DOI 10.1063/5.0012490. - ISSN 1077-3118(eISSN)
Примечания : Cited References: 29. - This work was supported by the Russian Science Foundation under Grant No. 18-12-00415. The research was also carried out as part of the state task of the Ministry of Science of the Russian Federation (No. AAAA-A17-117021310366-5).
Предметные рубрики: HEAT
MAGNETIZATION
Аннотация: We report upon the specific heat and magnetocaloric properties of Cu2MnBO5 over a temperature range of 60–350 K and in magnetic fields up to 18 kOe. It is found that at temperatures below the Curie temperature (TC ∼ 92 K), CP(T)/T possesses a linear temperature-dependent behavior, which is associated with the predominance of two-dimensional antiferromagnetic interactions of magnons. The temperature independence of CP/T = f(T) is observed in the temperature range of 95–160 K, which can be attributed to the excitation of the Wigner glass phase. The magnetocaloric effect [i.e., the adiabatic temperature change, ΔTad (T,H)] is assessed through a direct measurement or an indirect method using the CP(T,H) data. Owing to its strong magnetocrystalline anisotropy, an anisotropic magnetocaloric effect (MCE) or the rotating MCE [ΔTadrot (T)] is observed in Cu2MnBO5. A deep minimum in the ΔTadrot (T) near the TC is observed and ascribed to the anisotropy of the paramagnetic susceptibility.
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2.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Arauzo A., Bartolome J., Molokeev M. S., Dudnikov V. A., Solovyov L., Borus A., Ovchinnikov S. G.
Заглавие : Anisotropic thermal expansion and electronic transitions in the Co3BO5 ludwigite
Место публикации : Dalton Trans.: Royal Society of Chemistry, 2022. - Vol. 51, Is. 16. - С. 6345-6357. - ISSN 14779226 (ISSN), DOI 10.1039/d2dt00270a
Примечания : Cited References: 57. - We are grateful to the Russian Foundation for Basic Research (project no. 20-02-00559 and 21-52-12033) for supporting this paper. This work was performed within the framework of the budget project no. 0287-2021-0013 for the Institute of Chemistry and Chemical Technology SB RAS. We acknowledge the financial support from the Spanish Ministry of Economy, Industry and Competitiviness (MINECO), (Grant No. MAT2017-83468-R) and from the regional Government of Aragón (E12-20R RASMIA project)
Аннотация: The investigations of the crystal structure, magnetic and electronic properties of Co3BO5 at high temperatures were carried out using powder X-ray diffraction, magnetic susceptibility, electrical resistivity, and thermopower measurements. The orthorhombic symmetry (Sp.gr. Pbam) was observed at 300 K and no evidence of structural phase transitions was found up to 1000 K. The compound shows a strong anisotropy of the thermal expansion. A large negative thermal expansion along the a-axis is observed over a wide temperature range (T = 300–600 K) with αa = −35 M K−1 at T = 500 K with simultaneous expansion along the b- and c-axes with αb = 70 M K−1 and αc = 110 M K−1, respectively. The mechanisms of thermal expansion are explored by structural analysis. The activation energy of the conductivity decreases significantly above 700 K. Electronic transport was found to be a dominant conduction mechanism in the entire temperature range. The correlations between the thermal expansion, electrical resistivity, and effective magnetic moment were revealed and attributed to the evolution of the spin state of Co3+ ions towards the spin crossover and gradual charge-ordering transition.
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3.

Вид документа : Статья из сборника (однотомник)
Шифр издания :
Автор(ы) : Gokhfeld Yu. S., Kazak N. V., Molokeev M. S., Dudnikov V. A., Solovyov L. A., Ovchinnikov S. G.
Заглавие : Anisotropic thermal expansion in Co3BO5 ludwigite
Коллективы : Российская академия наук, Физико-технический институт им. Е.К. Завойского ФИЦ Казанского научного центра РАН, Казанский (Приволжский) федеральный университет, Euro-Asian Symposium "Trends in MAGnetism", "Trends in MAGnetism", Euro-Asian Symposium
Место публикации : VIII Euro-Asian symposium "Trends in magnetism" (EASTMAG-2022): Book of abstracts/ program com. S. G. Ovchinnikov [et al.]. - 2022. - Vol. 2, Sect. H: Magnetism of strongly correlated electron systems. - Ст.H.P6. - P.87-88. - ISBN 978-5-94469-051-7
Примечания : Cited References: 3. - Support by RFBR 20-02-00559 and 21-52-12033 ННИО_а is acknowledged
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4.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Moshkina E. M., Nazarenko I. I., Veligzhanin A., Molokeev M. S., Eremin E. V., Bezmaternykh L. N.
Заглавие : Chemical disorder reinforces magnetic order in ludwigite (Ni,Mn)3BO5 with Mn4+ inclusion
Место публикации : J. Magn. Magn. Mater. - 2018. - Vol. 465. - P.201-210. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2018.05.068
Примечания : Cited References: 31
Ключевые слова (''Своб.индексиров.''): oxide--oxyborate--magnetism--crystal growth--exafs
Аннотация: Crystals of ludwigite Ni2.14Mn0.86BO5 were synthesized by flux growth technique. We show in the paper that it contains Mn3+ and Mn4+. A possible mechanism of the manganese valence states stabilization has been proposed. The structural and magnetic characterization of the synthesized samples has been carried out in detail. The cations composition and Mn valence states of the crystal were determined using X-ray diffraction and EXAFS technique. The comparative analysis was carried out between the studied crystal and Ni2MnBO5 synthesized previously. Magnetic susceptibility measurements were carried out. The magnetic transition in the studied composition occurs at the 100 K that is higher than in Ni2MnBO5 although the studied composition is more disordered. The calculations of the exchange integrals in the frameworks of indirect coupling model revealed strong antiferromagnetic interactions. The several magnetic subsystems existence hypothesis was supposed. The possible magnetic structure was suggested from the energies estimation for different ordering variants.
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5.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Moshkina E. M., Eremin E. V., Veligzhanin, Alexey, Pavlovskiy M. S., Sofronova S. N., Titova, Veronika, Bezmaternykh L. N.
Заглавие : Concentration transition in Cu2(Mn,Ga)BO5 solid solutions
Колич.характеристики :13 с
Место публикации : J. Magn. Magn. Mater. - 2023. - Vol. 584. - Ст.171072. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2023.171072. - ISSN 18734766 (eISSN)
Примечания : Cited References: 27
Аннотация: The effects related to the conversion of magnetic structures of a Cu2MnBO5 ferrimagnet to a Cu2GaBO5 antiferromagnet under the Mn3+ → Ga3+ substitution were studied. The properties of four single crystal samples with the gallium concentration x  = 0.04, 0.11, 0.17, 0.25 were examined. The chemical composition and valence state of the samples were determined by X-ray absorption spectroscopy element-sensitive technique. Distribution of the 3d metal ions over crystallographic positions was studied using the first principle calculations by Wien2k program. The evolution of the magnetic properties was investigated by the measurements of the temperature and field dependences of magnetization, dc and ac magnetic susceptibility. In agreement with the previous study of the structure evolution of Cu2Mn1-xGaxBO5 solid solutions, the critical concentration upon a change in the magnetic ordering type was found in the range x  = 0.17–0.25. The non-monotonic behavior of magnetization in terms of the gallium content was found in the concentration range of 0.04–0.17. A complex pattern of magnetic phase transitions belonging to the concentration phase boundary was obtained in the compounds with gallium being within the range x  = 0.17–0.25. One could observe the splitting of the peaks of the real part of ac-susceptibility of the high-temperature phase transition in the Cu2MnBO5-like phase (x = 0.04, 0.11) and that of the low-temperature one at the concentration boundary (x = 0.17, 0.25) with different frequency and orientational dependence. The type and origin of the multiple phase transitions observed in the studied samples were analyzed.
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6.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Kazak N. V., Ivanova N. B., Rudenko V. V., Ovchinnikov S. G., Vasil'Ev A. D., Knyazev Yu. V.
Заглавие : Conductivity study of Co3O2BO3 and Co 3-xFexO2BO3 oxyborates
Коллективы : Moscow International Symposium on Magnetism
Место публикации : Solid State Phenomena. - 2009. - Vol. 152-153. - С. 104-107. - ISSN 10120394 (ISSN); 390845168X (ISBN); 9783908451686 (ISBN), DOI 10.4028/www.scientific.net/SSP.152-153.104
Ключевые слова (''Своб.индексиров.''): doped cobaltite--electrical conductivity--ludwigite--variable-range hopping--crystal structure--electric conductivity--magnetic materials--single crystals--crystal structure--electric conductivity--magnetic materials--magnetism--single crystals--electrical conductivity--electrical resistivity--experimental data--mott variable-range hopping--oxyborates--temperature regions--variable-range hopping--doped cobaltite--ludwigite--variable range hopping--cobalt--cobalt
Аннотация: Single crystals of cobalt oxyborates Co3O2BO 3 and Co3-xFexO2BO3 were synthesized. The crystal structure and electric properties were investigated. The difference in the electrical resistivity behaviors was found. For parent Co3O2BO3 nor simple activation law, nor Mott variable range hopping (VRH) are acquirable to describe the experimental data in wide temperature region. In contrast for Co3-xFex O 2BO3 Mott's variable-range hopping conductivity clearly dominates.
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7.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Bezmaternykh L. N., Eremin E. V., Chernyshov A., Bovina A. F.
Заглавие : Crystal growth, magnetic properties and analysis of possible magnetic ordering of Ni5Sn(BO5)2 with ludwigite structure
Место публикации : Phys. Status Solidi B. - 2018. - Vol. 255, Is. 12. - Ст.1800281. - ISSN 03701972 (ISSN), DOI 10.1002/pssb.201800281
Примечания : Cited References: 15
Ключевые слова (''Своб.индексиров.''): ferrimagnets--ludwigites--magnetic phase transitions--quasi-low-dimensional structures
Аннотация: The ludwigite Ni5Sn(BO5)2 belongs to a family of oxyborates, and has an ordered distribution of nonmagnetic Sn ions. This material is studied here using magnetic measurements. Ni5Sn(BO5)2 does not show full long-range magnetic order, but exhibits a partial ordering at 73 K. A theoretical group analysis is performed and different models of the magnetic structure of Ni5Sn(BO5)2 are discussed.
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8.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Sofronova S. N., Moshkina E. M., Nazarenko I. I., Seryotkin Yu. V., Nepijko S. A., Ksenofontov V., Medjanik K., Veligzhanin A. A., Bezmaternykh L. N.
Заглавие : Crystal growth, structure, magnetic properties and theoretical exchange interaction calculations of Cu2MnBO5
Место публикации : J. Magn. Magn. Mater.: Elsevier, 2016. - Vol. 420. - P.309-316. - ISSN 03048853 (ISSN), DOI 10.1016/j.jmmm.2016.07.019
Примечания : Cited References: 35. - X-ray diffraction experiment was carried out at the Centre on Molecular Design and Ecologically Safe Technologies at the Novosibirsk State University. The reported study was funded by Russian Foundation for Basic Research (RFBR) and Government of Krasnoyarsk Territory according to the research project No. 16-42-243028.
Предметные рубрики: SPIN-GLASS BEHAVIOR
SINGLE-CRYSTALS
SUPEREXCHANGE INTERACTIONS
LUDWIGITE
DIELECTRICS
CO3B2O6NI3B2O6
WARWICKITES
FE3O2BO3
IFEFFIT
NI3B2O6
Ключевые слова (''Своб.индексиров.''): oxyborates--ludwigites--xmcd--exafs--magnetism
Аннотация: Single crystals of ludwigite Cu2MnBO5 were synthesized by flux growth technique. The detailed structural and magnetic characterizations of the synthesized samples have been carried out. The cations composition of the studied crystal was determined using X-ray diffraction and EXAFS technique, the resulting composition differ from the content of the initial Mn2O3–CuO components of the flux. Magnetic susceptibility measurements and the calculations of the exchange integrals in frameworks of indirect coupling model revealed that monoclinic distortions strongly affect exchange interactions and appearance of magnetic ordering phase at the temperature T=93 K. The hypothesis of the existence of several magnetic subsystems was supposed. © 2016 Elsevier B.V.
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9.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Ivanova N. B., Kazak N. V., Knyazev Yu.V., Velikanov D. A., Bezmaternykh L. N., Ovchinnikov S. G., Vasiliev A. D., Platunov M. S., Bartolomé J., Patrin G. S.
Заглавие : Crystal structure and magnetic anisotropy of ludwigite Co2FeO2BO3
Место публикации : J. Experim. Theor. Phys. - 2011. - Vol. 113, Is. 6. - P.1015-1024. - DOI 10.1134/S1063776111140172
Примечания : Cited References: 14. - This work was supported by the Russian Founda tion for Basic Research (project no. 090200171a), the Russian Science Foundation (President project no. MK5632.2010.2), and the program of the Divi sion of Physical Sciences of the Russian Academy of Sciences “Strong Electronic Correlations.” REFE
Аннотация: Co3O2BO3 and Co2FeO2BO3 single crystals with a ludwigite structure are fabricated, and their crystal structure and magnetic properties are studied in detail. Substituted ludwigite Co2FeO2BO3 undergoes two-stage magnetic ordering at the temperatures characteristic of Fe3O2BO3 (T N1 ≈ 110 K, T N2 ≈ 70 K) rather than Co3O2BO3 (T N = 42 K). This effect is explained in terms of preferred occupation of nonequivalent crystallographic positions by iron, which was detected by X-ray diffraction. Both materials exhibit a pronounced uniaxial magnetic anisotropy. Crystallographic direction b is an easy magnetization axis. Upon iron substitution, the cobalt ludwigite acquires a very high magnetic hardness.
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10.

Вид документа : Статья из журнала
Шифр издания :
Автор(ы) : Knyazev Yu.V., Ivanova N. B., Kazak N. V., Platunov M. S., Bezmaternykh L. N., Velikanov D. A., Vasiliev A. D., Ovchinnikov S. G., Yurkin G. Yu.
Заглавие : Crystal structure and magnetic properties of Mn substituted ludwigite Co3O2BO3
Место публикации : J. Magn. Magn. Mater.: Elsevier Science BV, 2012. - Vol. 324, Is. 6. - P.923-927. - ISSN 0304-8853, DOI 10.1016/j.jmmm.2011.07.044
Примечания : Cited References: 15. - The study was supported by the Russian Foundation for Basic Research (Project no. 09-02-00171-a), the Federal Agency for Science and Innovation (Rosnauka) (Project no. MK-5632.2010.2), the Physical Division of the Russian Academy of Science, the program "Strongly Correlated Electrons", Project 2.3.1.
Предметные рубрики: BOND VALENT SUMS
COORDINATION CHEMISTRY
OXIDATION -STATE
O BONDS
COMPLEXES
MANGANESE
COBALT
Ключевые слова (''Своб.индексиров.''): transition metal oxyborate--distinct crystallographic position--spin glass magnetic ordering
Аннотация: The needle shape single crystals Co3−x MnxO2BO3 with ludwigite structure have been prepared. According to the X-ray diffraction data the preferable character of distinct crystallographic positions occupation by Mn ions is established. Magnetization field and temperature dependencies are measured. Paramagnetic Curie temperature value Θ=−100 K points out the predominance of antiferromagnetic interactions. Spin-glass magnetic ordering takes the onset at TN=41 K. The crystallographic and magnetic properties of Co3O2BO3:Mn are compared with the same for the isostructural analogs Co3O2BO3 and CoO2BO3:Fe.
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