WoS İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12573/394

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Subject: search.filters.subject.Boron-RichWoS Q: search.filters.wosQuartile.Q1

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  • Article
    Boron-Rich Amorphous Boron Oxides From Ab Initio Simulations
    (Elsevier, 2023-03) Karacaoglan, Aysegul Ozlem Cetin; Durandurdu, Murat
    Amorphous boron oxide (BxO1-x, 0.5 <= x <= 95) configurations are simulated by means of an ab initio molecular dynamics technique and their microstructure and mechanical properties are revealed in details. With increasing B content, the average B-coordination noticeably increases from 3.18 to 5.62 whereas the O-coordination, sur-prisingly, remains almost null, about 2.0. The formation of complete B12 molecules is observed after 80% B concentrations. Chemical segregation is witnessed in most models and hence the resulting configurations show B: B2O3 phase separations. The mechanical properties (bulk, shear and Young moduli, Vickers hardness and microhardness) substantially increase with increasing B content. The amorphous materials (BxO1-x, x >= 80) are classified as hard materials. Within the limitations of DFT calculations and approaches used, we speculate that there is a ductile-to-brittle transition at around 70-75% B contents.
  • Article
    Citation - WoS: 3
    Citation - Scopus: 2
    Ab Initio Study of Boron-Rich Amorphous Boron Carbides
    (Wiley, 2023-01-10) Yildiz, Tevhide Ayca; Durandurdu, Murat
    Amorphous boron carbide compositions having high B contents (BxC1-x, 0.50 <= x <= 0.95) are systematically created by way of ab initio molecular dynamics calculations, and their structural, electrical, and mechanical characteristics are inclusively investigated. The coordination number of both B and C atoms increases progressively with increasing B/C ratio and more close-packed materials having pentagonal pyramid motifs form. An amorphous diamond-like local arrangement is found to be dominant up to 65% B content, and beyond this content, a mixed state of amorphous diamond- and B-like structures is perceived in the models because sp(3) hybridization around C atoms is still leading one for all compositions. The pentagonal pyramid motifs around C atoms are anticipated to appear beyond 65% content. The intericosahedral linear C-B-C chains do not form in any model. All amorphous boron carbides are semiconducting materials. The mechanical properties gradually increase with increasing B concentration, and some amorphous compositions are proposed to be hard materials on the basis of their Vickers hardness estimation.