Influence of boron vacancies on phase stability, bonding and structure ofMB2(M  =  Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W) with AlB2type structure

Dahlqvist, Martin; Jansson, Ulf; Rosén, Johanna

doi:10.1088/0953-8984/27/43/435702

Cited by 42 publications

(30 citation statements)

References 43 publications

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“…[65,66] In order to observe the trend better, the ∆H is plotted with respect to transition metals in Figure 2 Despite the experimental synthesis of Ru 3 Al 2 B 2 , [46] the calculated ∆H is a relatively high positive value (0.07 eV/atom). This might imply that either our exchangecorrelation function for Ru is not appropriate or this compound could be formed experimentally because of the influences of vibrational entropy at high temperature and/or boron vacancies entropy effects [67]. According to the recent computational screening on inorganic crystal structure database (ICSD), [68] 20% of all compounds have instability of ∆H larger than 0.036 eV/atom.…”

Section: A Stabilities Of Mab Phasesmentioning

confidence: 99%

Novel MAB phases and insights into their exfoliation into 2D MBenes

et al. 2019

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Considering the recent breakthroughs in the synthesis of novel two-dimensional (2D) materials from layered bulk structures, ternary layered transition metal borides, known as MAB phases, have come under scrutiny as a means of obtaining novel 2D transition metal borides, so-called MBene. Here, based on a set of phonon calculations, we show the dynamic stability of many Al-containing MAB phases, MAlB (M = Ti, ). By comparing the formation energies of these MAB phases with those of their available competing binary M−B and M−Al, and ternary M−Al−B phases, we find that some of the Sc-, Ti-, V-, Cr-, Mo-, W-, Mn-, Tc-, and Fe-based MAB phases could be favorably synthesized in an appropriate experimental condition. In addition, by examining the strengths of various bonds in MAB phases via crystal orbital Hamilton population and spring constant calculations, we find that the B−B and then M−B bonds are stiffer than the M−Al and Al−B bonds. The different strength between these bonds implies the etching possibility of Al atoms from MAB phases, consequently forming various 2D MB, M 2 B 3 , and M 3 B 4 MBenes. Furthermore, we employ the nudged elastic band method to investigate the possibility of the structural phase transformation of the 2D MB MBenes into graphene-like boron sheets sandwiched between transition metals and find that the energy barrier of the transformation is less than 0.4 eV/atom.

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Section: A Stabilities Of Mab Phasesmentioning

confidence: 99%

Novel MAB phases and insights into their exfoliation into 2D MBenes

et al. 2019

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“…On the other hand, in MgB 2 the peculiar self-doping exists thanks to the boron-related electrons at the Fermi level; at the same time also the s states of Mg donate their electrons to the boron-derived conduction bands (metallic B). It is also worth mentioning that B vacancies (a common defect occurring in diborides) enhance the DOS even further (more than twice for doping of about 0.5%) [8]. Besides the many similarities with MgB 2 , the lower T c values (7.31 and 8.33 K instead of 39 K) are accounted for by the differences in the electronic structure and Fermi surface.…”

Section: Discussionmentioning

confidence: 99%

“…Maximum superconducting temperatures T c = 8.33 K and 7.31 K were reached in Zr 0.96 V 0.04 B 2 and Hf 0.97 V 0.03 B 2 , respectively, at the upper solubility limit of V (x ≈ 0.04). X-ray powder diffraction (XRD) patterns [7] indicate that an increase in V doping does not change the in-plane lattice parameter a, while it reduces the interlayer distance c. At the same time, it has been shown that the structural and electronic properties of these compounds are influenced by the presence of B vacancies [8].…”

Section: Introductionmentioning

confidence: 99%

Doping-induced superconductivity of ZrB2 and HfB2

et al. 2017

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Unlike the widely studied s-type two-gap superconductor MgB 2 , the chemically similar compounds ZrB 2 and HfB 2 do not superconduct above 1 K. Yet it has been shown that small amounts of self or extrinsic doping (in particular with vanadium), can induce superconductivity in these materials. Based on results of different macroscopic and microscopic measurements, including magnetometry, nuclear magnetic resonance (NMR), resistivity, and muon-spin rotation (μ + SR), we present a comparative study of Zr 0.96 V 0.04 B 2 and Hf 0.97 V 0.03 B 2. Their key magnetic and superconducting features are determined and the results are considered within the theoretical framework of multiband superconductivity proposed for MgB 2. Detailed Fermi surface (FS) and electronic structure calculations reveal the difference between MgB 2 and transition-metal diborides.

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“…Compared to many other ceramics, its resistivity is relatively low, which enables applications such as wear-resistant electrical contacts. While Zr-Zr-and Zr-B-bonds are strong and ionic/covalent in character, the B-Bbonds are significantly stronger whenever they can form a single sheet of hexagons [33,34], known as borophene (in analogy with graphene). This is possible for the AlB2-type structured materials (P6/mmm space group), to which ZrB2 belongs.…”

Section: Zrbmentioning

confidence: 99%