Self-healing in B<sub>12</sub>P<sub>2</sub> through Mediated Defect Recombination

Huber, Sebastiaan P.; Gullikson, Eric M.; Frye, Clint D.; Edgar, James H.; Kruijs, R. W. E. van de; Bijkerk, F.

doi:10.1021/acs.chemmater.6b04075

Cited by 11 publications

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“…B 12 P 2 is a wide band gap semiconductor (3.35 eV) [9], a thermoelectric with a high positive Seebeck coefficient [10] and displays both high thermal and chemical stabilities as well as an extreme resistance to damage induced by high energy particle radiations [11,12]. This peculiar behaviour is attributed to a self-healing mechanism whose origin has recently been proposed to lie in the very low activation energy for the diffusion and recombination of interstitial-vacancy pairs [13] and makes it a potential candidate for betavoltaics [12].…”

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confidence: 99%

Polarization Selectivity in Vibrational Electron-Energy-Loss Spectroscopy

et al. 2019

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Orientation-dependent aloof-beam vibrational electron-energy-loss spectroscopy is carried out on uniaxial icosahedral B12P2 submicron crystals. We demonstrate that the high sensitivity of the signal to the crystal orientation allows for an unambiguous determination of the symmetry of normal-modes occurring at the Brillouin zone center of this anisotropic compound. The experimental results are assessed using first-principles quantum mechanical calculations (density functional theory) of the dielectric response of the specimen. The high spatial resolution inherent to this technique when implemented in the transmission electron microscope thus opens the door to nanoscale orientationdependent vibrational spectroscopy.

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confidence: 99%

Polarization Selectivity in Vibrational Electron-Energy-Loss Spectroscopy

et al. 2019

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“…Spectral broadening in the DFT-XCH method is artificially simulated by the uniform linewidth broadening of individual defect states at a fixed width of 0.2 eV, which is an empirical value. This value accurately models the broadening of various defect states in boron compounds, such as boron vacancies and oxygen substitutional defects in h-BN 19 , as well as phosphorus vacancies in the icosahedral boron phosphide B 12 P 2 20 . Even though the defect spectroscopy was simulated at a temperature of 0 K and spectral broadening can in principle be influenced by thermal structural distortions induced by a finite temperature, we have verified that the broadening of these defect transitions reamins unchanged at a finite temperature of 300 K. Since the defect states, associated with the structural defects, are single excited states located in the band gap, which are therefore strongly localized, they are insensitive to perturbations of the local atomic structure.…”

Section: Computational Resultsmentioning

confidence: 88%

“…A. X-ray absorption spectroscopy of point defects X-ray absorption spectroscopy of the B K-edge is sensitive to point defects of the crystal structure in various boron compounds [18][19][20][41][42][43] . To determine whether point defects are capable of explaining the broad onset of absorption observed in experiment, we have computed the x-ray absorption spectra for several point defects.…”

Section: Computational Resultsmentioning

confidence: 99%

“…In parallel with typical experimental techniques such as x-ray diffraction, to characterize the long range order found in the sample crystal structure, one could use methods that study the structural and chemical properties on a local atomic scale. This is possible with X-ray absorption near-edge spectroscopy (XANES), as it is sensitive to structural point defects in the boron K-edge of various boron compounds [18][19][20] and is typically highly sensitive to the different crystal phases of a particular compound. With the recent prediction 21 of the hexagonal phase of boron phosphide (h-BP), the subject of several recent studies [22][23][24][25][26][27] , XANES is a promising candidate as a method that will be able to determine the presence of this unintended crystal phase.…”

Section: Introductionmentioning

confidence: 99%

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Determining crystal phase purity in c-BP through X-ray absorption spectroscopy

Huber

Медведев

Gullikson

et al. 2017

Phys. Chem. Chem. Phys.

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We employ X-ray absorption near-edge spectroscopy at the boron K-edge and the phosphorus L-edge to study the structural properties of cubic boron phosphide (c-BP) samples. The X-ray absorption spectra are modeled from first-principles within the density functional theory framework using the excited electron core-hole (XCH) approach. A simple structural model of a perfect c-BP crystal accurately reproduces the P L-edge, however it fails to describe the broad and gradual onset of the B K-edge. Simulations of the spectroscopic signatures in boron 1s excitations of intrinsic point defects and the hexagonal BP crystal phase show that these additions to the structural model cannot reproduce the broad pre-edge of the experimental spectrum. Calculated formation enthalpies show that, during the growth of c-BP, it is possible that amorphous boron phases can be grown in conjunction with the desired boron phosphide crystalline phase. In combination with experimental and theoretically obtained X-ray absorption spectra of an amorphous boron structure, which have a similar broad absorption onset in the B K-edge spectrum as the cubic boron phosphide samples, we provide evidence for the presence of amorphous boron clusters in the synthesized c-BP samples.

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“…Furthermore, due to their self-healing property resistant to structural damage, when subjected to high-energy electron radiation, B 12 As 2 and B 12 P 2 are candidates for radiation resistant applications [91,92], including beta-voltaic devices [93]. Recently, B 12 As 2 has been suggested as a candidate for thermoelectric applications at high temperature [29,30].…”

Section: Boron Subarsenide and Subphosphidementioning

confidence: 99%

Disordered Icosahedral Boron-Rich Solids: A Theoretical Study of Thermodynamic Stability and Properties

Ektarawong¹

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The cover page illustrates the crystal structure of disordered boron carbide (B 4 C), projected on the (100) r crystal plane in rhombohedral symmetry.The cover image is visualized by the VESTA package. Red and white spheres represent boron and carbon atoms, respectively.During the course of research underlying this thesis, Annop Ektarawong was enrolled in Agora Materiae, a multidisciplinary doctoral program at Linköping University, Sweden.c Annop Ektarawong Printed by LiU-Tryck 2017 AbstractThis thesis is a theoretical study of configurational disorder in icosahedral boronrich solids, in particular boron carbide, including also the development of a methodological framework for treating configurational disorder in such materials, namely superatom-special quasirandom structure (SA-SQS). In terms of its practical implementations, the SA-SQS method is demonstrated to be capable of efficiently modeling configurational disorder in icosahedral boron-rich solids, whiles the thermodynamic stability as well as the properties of the configurationally disordered icosahedral boron-rich solids, modeled from the SA-SQS method, can be directly investigated, using the density functional theory (DFT).In case of boron carbide, especially B 4 C and B 13 C 2 compositions, the SA-SQS method is used for modeling configurational disorder, arising from a high concentration of low-energy B/C substitutional defects. The results, obtained from the DFT-based calculations, demonstrate that configurational disorder of B and C atoms in boron carbide is not only thermodynamically favored at high temperature, but it also plays an important role in altering the properties of boron carbide − for example, restoration of higher rhombohedral symmetry of B 4 C, a metal-tononmetal transition and a drastic increase in the elastic moduli of B 13 C 2 . The configurational disorder can also explain large discrepancies, regarding the properties of boron carbide, between experiments and previous theoretical calculations, having been a long standing controversial issue in the field of icosahedral boronrich solids, as the calculated properties of the disordered boron carbides are found to be in qualitatively good agreement with those, observed in experiments. In order to investigate the configurational evolution of B 4 C as a function of temperature, beyond the SA-SQS level, a brute-force cluster-expansion method in combination with Monte Carlo simulations is implemented. The results demonstrate that configurational disorder in B 4 C indeed essentially takes place within the icosahedra in a way that justifies the focus on low-energy defect patterns of the superatom picture.The investigation of the thermodynamic stability of icosahedral carbon-rich iii iv boron carbides beyond the believed solubility limit of carbon (20 at.% C) demonstrates that, apart from B 4 C generally addressed in the literature, B 2.5 C represented by B 10 C p 2 (CC) is predicted to be thermodynamically stable with respect to B 4 C as well as pure boron and carbon under high pressure...

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Self-healing in B₁₂P₂ through Mediated Defect Recombination

Cited by 11 publications

References 27 publications

Polarization Selectivity in Vibrational Electron-Energy-Loss Spectroscopy

Polarization Selectivity in Vibrational Electron-Energy-Loss Spectroscopy

Determining crystal phase purity in c-BP through X-ray absorption spectroscopy

Disordered Icosahedral Boron-Rich Solids: A Theoretical Study of Thermodynamic Stability and Properties

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Self-healing in B12P2 through Mediated Defect Recombination

Cited by 11 publications

References 27 publications

Polarization Selectivity in Vibrational Electron-Energy-Loss Spectroscopy

Polarization Selectivity in Vibrational Electron-Energy-Loss Spectroscopy

Determining crystal phase purity in c-BP through X-ray absorption spectroscopy

Disordered Icosahedral Boron-Rich Solids: A Theoretical Study of Thermodynamic Stability and Properties

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Product

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Self-healing in B₁₂P₂ through Mediated Defect Recombination