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Structure and properties of MgB2bulks: Ab-initio simulations compared to experiment

Romaka, V V; Prikhna, T A; Eisterer, M; Shapovalov, A P; Goldacker, W; Moshchil, V E; Kozyrev, A; Rindfleisch, M; Tompsic, M; Hellstrom, E E; Grechnev, G E; Zhang, V Sh; Yang, F; Li, Ch

Analysis of XRD patterns by Rietveld refinement has been shown that the main phase of superconducting MgB$_{2}$-based bulk materials (with high level of superconducting characteristics) has AlB$_{2}$ type structure and near MgB$_{1.8-1.68}$O$_{0.2-0.32}$ stoichiometry. The materials demonstrated the critical current densities up to 0.9 – 0.4 MA/cm$^{2}$ jc (at 0 - 1 T, 20 K); up to 15 T B$_{c2}$ (at 22.5 K) and B$_{irr}$ (at 18 K). The ab-initio simulation confirmed (1) benefits in binding energy and enthalpy of formation if stoichiometry of the solid solution is near MgB$_{1.75}$O$_{0.25}$; (2) energetic advantage in case if impurity oxygen present only in each second boron plane of MgB2 cell while the first boron plane of the same cell stays pristine and location of substituted oxygen atoms in the nearby positions. Besides, the results of ab-initio modeling allow explanation of the tendency towards segregation of O-impurity in MgB$_{2}$ structure during synthesis or sintering, and formation of Mg-B-O inclusions or nanolayers (with MgO type of structure) which effect pinning. Calculated transition temperatures, T$_{c}$, for MgB$_{1.75}$O$_{0.25}$ occurred to be 23.3 K, while for MgB$_{2}$ it was 21.13 K only. ... mehr

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Verlagsausgabe §
DOI: 10.5445/IR/1000127808
Veröffentlicht am 16.12.2020
DOI: 10.1088/1757-899X/756/1/012020
Cover der Publikation
Zugehörige Institution(en) am KIT Steinbuch Centre for Computing (SCC)
Institut für Technische Physik (ITEP)
Publikationstyp Zeitschriftenaufsatz
Publikationsjahr 2020
Sprache Englisch
Identifikator ISSN: 1757-899X
KITopen-ID: 1000127808
Erschienen in IOP conference series / Materials science and engineering
Verlag IOP Publishing
Band 756
Heft 1
Seiten Art. Nr.: 012020
Bemerkung zur Veröffentlichung 2019 International Cryogenic Materials Conference, ICMC 2019; Connecticut Convention CenterHartford; United States; 21 July 2019 through 25 July 2019
Vorab online veröffentlicht am 30.06.2020
Nachgewiesen in Scopus
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