Abstract
γ-B28 is a recently established high-pressure phase of boron. Its structure consists of icosa-hedral B12 clusters and B2 dumbbells in a NaCl-type arrangement (B2)δ+(B12)δ− and displays a significant charge transfer δ ∼ 0.5–0.6. The discovery of this phase proved to be essential for the understanding and construction of the phase diagram of boron. It was first experimentally obtained as a pure boron allotrope in early 2004 and its structure was discovered in 2006. This paper reviews recent results and contentious issues related to the equation of state, hardness, putative isostructural phase transformation at ∼40 GPa, and debates on the nature of chemical bonding in this phase. Our analysis confirms that (a) calculations based on density functional theory give an accurate description of its equation of state, (b) the reported isostructural phase transformation in γ-B28 is an artifact, (c) the best estimate of hardness of this phase is 50 GPa, (d) chemical bonding in this phase has a significant degree of ionicity. Apart from presenting an overview of the previous results within a consistent view grounded in experiment, thermodynamics and quantum mechanics, we present new results on Bader charges in γ-B28 using different levels of quantum-mechanical theory (GGA, exact exchange, and HSE06 hybrid functional), and show that the earlier conclusion about a significant degree of a partial ionicity in this phase is very robust. An additional insight into the nature of the partial ionicity is obtained from a number of boron structures theoretically constructed in this work.
Similar content being viewed by others
References
Douglas, B.E. and Ho, S.-M., Structure and Chemistry of Crystalline Solids, New York: Springer, 2006.
Amberger, E. and Ploog, K., Bildung der Gitter des Reinen Bors, J. Less-Common Metals, 1971, vol. 23, pp. 21–31.
Sanz, D.N., Loubeyre, P., and Mezouar, M., Equation of State and Pressure-Induced Amorphization of beta-Boron from X-ray Measurements up to 100 GPa, Phys. Rev. Lett., 2002, vol. 89, art. 245501 (4).
Van Setten, M.J., Uijttewaal, M.A., de Wijs, G.A., and de Groot, R.A., Thermodynamic Stability of Boron: The Role of Defects and Zero Point Motion, J. Am. Chem. Soc., 2007, vol. 129, pp. 2458–2465.
Widom, M. and Mikhalkovic, M., Symmetry-Broken Crystal Structure of Elemental Boron at Low Temperature, Phys. Rev. B, 2008, vol. 77, art. 064113.
Ogitsu, T., Gygi, F., Reed, J., Motome, Y., Schwegler, E., and Galli, G., Imperfect Crystal and Unusual Semiconductor: Boron, a Frustrated Element, J. Am. Chem. Soc., 2009, vol. 131, pp. 1903–1909.
Oganov, A.R., Chen, J., Gatti, C., Ma, Y.-M., Yu, T., Liu, Z., Glass, C.W., Ma, Y.-Z., Kurakevych, O.O., and Solo-zhenko, V.L., Ionic High-Pressure Form of Elemental Boron, Nature, 2009, vol. 457, pp. 863–867.
Oganov, A.R. and Solozhenko, V.L., Boron: a Hunt for Superhard Polymorphs, J. Superhard Materials, 2009, vol. 31, no. 5, pp. 285–291.
Wentorf, R.H., Jr., Boron: Another Form, Science, 1965, vol. 147, no. 3653, pp. 49–50.
Oganov, A.R. and Glass, C.W., Crystal Structure Prediction Using ab initio Evolutionary Techniques: Principles and Applications, J. Chem. Phys., 2006, vol. 124, art. 244704.
Oganov, A.R., Lyakhov, A.O., and Valle, M., How Evolutionary Crystal Structure Prediction Works and Why, Acc. Chem. Res., 2011, vol. 44, pp. 227–237.
Li, Q., Ma, Y., Oganov, A.R., Wang, H.B., Wang, H., Xu, Y., Cui, T., Mao, H.-K., and Zou, G., Superhard Monoclinic Polymorph of Carbon, Phys. Rev. Lett., 2009, vol. 102, art. 175506 (4).
Weintraub, E., On the Properties and Preparation of the Element Boron, J. Ind. Eng. Chem., 1911, vol. 3, no. 5, pp. 299–301.
Brazhkin, V.V., Interparticle Interaction in Condensed Media: Some Elements Are “More Equal than Others”, Physics Uspekhi, 2009, vol. 52, no. 4, pp. 369–376.
Zhu, Q., Oganov, A.R., Salvado, M., Pertierra, P., and Lyakhov, A.O., Denser than Diamond: ab initio Search for Superdense Carbon Allotropes, Phys. Rev. B, 2011, vol. 83, art. 193410.
Gabunia, D., Tsagareishvili, O., Darsavelidze, G., Lezhava, G., Antadze, M., and Gabunia, L., Preparation, Structure and Some Properties of Boron Crystals with Different Content of 10B and 11B Isotopes, J. Solid State Chem., 2004, vol. 177, pp. 600–604.
Amberger, E. and Stumpf, W., Boron, Gmelin Handbook of Inorganic Chemistry, Berlin: Springer-Verlag, 1960, pp. 112–238.
Solozhenko, V.L., Kurakevych, O.O., and Oganov, A.R., On the Hardness of a New Boron Phase, Orthorhombic γ-B28, J. Superhard Mater., 2008, vol. 30, no. 6, pp. 428–429.
Will, G. and Kiefer, B., Electron Deformation Density in Alpha-Boron, Z. Anorg. Allg. Chem., 2001, vol. 627, pp. 2100–2104.
Zarechnaya, E.Y., Dubrovinsky, L., Dubrovinskaia, N., Miyajima, N., Filinchuk Y., Chernyshov, D., and Dmitriev, V., Synthesis of an Orthorhombic High-Pressure Boron Phase, Sci. Tech. Adv. Mat., 2008, vol. 9, art. 044209.
Zarechnaya, E.Y., Dubrovinsky, L., Dubrovinskaia, N., Filinchuk, Y., Chernyshov, D., Dmitriev, V., Miyajima, N., El Goresy, A., Braun, H.F., Van Smaalen, S., Kantor, I., Kantor, A., Prakapenka, V., Hanfland, M., Mikhailushkin, A.S., Abrikosov, I.A., and Simak, S.I., Superhard Semiconducting Optically Transparent High-Pressure Phase of Boron, Phys. Rev. Lett., 2009, vol. 102, art. 185501.
Oganov, A.R., Solozhenko, V.L., Kurakevych, O.O., Gatti, C., Ma, Y.M., Chen, J., Liu, Z., and Hemley, R.J., Comment on ’superhard Semiconducting Optically Transparent High-Pressure Phase of Boron’, 2009, http://arxiv.org/abs/0908.2126.
Slack, G.A., Hejna, C.I., Garbauskas, M.F., and Kasper, J.S., The Crystal Structure and Density of β-Rhombohedral Boron, J. Sol. State Chem., 1988, vol. 76, pp. 52–63.
Vlasse, M., Naslain, R., Kasper, J.S., and Ploog, K., Crystal Structure of Tetragonal Boron Related to α-AlB12, J. Sol. State Chem., 1979, vol. 28, pp. 289–301.
Le Godec, Y., Kurakevych, O.O., Munsch, P., Garbarino, G., and Solozhenko, V.L., Equation of State of Ortho-rhombic Boron, γ-B28, Solid State Comm., 2009, vol. 149, pp. 1356–1358.
Jiang, C., Lin, Z., Zhang, J., and Zhao, Y., First-Principles Prediction of Mechanical Properties of gamma-Boron, Appl. Phys. Lett., 2009, vol. 94, art. 191906.
Rulis, P., Wang, L., and Ching, W.Y., Prediction of γ-B28 ELNES with Comparison to α-B12, Phys. Stat. Sol. (RRL), 2009, vol. 3, 133–135.
Zarechnaya, E., Dubrovinskaia, N., Caracas, R., Merlini, M., Hanfland, M., Filinchuk, Y., Chernyshov, D., Dmitriev, V., and Dubrovinsky, L., Pressure-Induced Isostructural Phase Transformation in γ-B28, Phys. Rev. B, 2010, vol. 82, art. 184111.
Haussermann, U. and Milhaylushkin, A.S., Structure and Bonding of γ-B28: Is the High Pressure Form of Elemental Boron Ionic? Inorg. Chem., 2010, vol. 49, pp. 11270–11275.
Isaev, E.I., Simak, S.I., Mikhaylushkin, A.S., Vekilov, Yu.Kh., Zarechnaya, E.Yu., Dubrovinsky, L., Dubrovinskaia, N., Merlini, M., Hanfland, M., and Abrikosov, I.A., Impact of Lattice Vibrations on Equation of State of the Hardest Boron Phase, Phys. Rev. B, 2011, vol. 83, art. 132106.
Mondal, S., van Smaalen, S., Schonleber, A., Filinchuk, Y., Chernyshov, D., Simak, S.I., Mikhaylushkin, A.S., Abrikosov, I.A., Zarechnaya, E., Dubrovinsky, L., and Dubrovinskaia, N., Electron-Deficient and Polycenter Bonds in the High-Pressure γ-B28 Phase of Boron, Phys. Rev. Lett., 2011, vol. 106, art. 215502.
Christy, A.G., Isosymmetric Structural Phase Transitions: Phenomenology and Examples, Acta Cryst. B, 1995, vol. 51, pp. 753–757.
Oganov, A.R. and Lyakhov, A.O., Towards the Theory of Hardness of Materials, J. Superhard Mater., 2010, vol. 32, no. 3, pp. 143–147.
Zhou, W., Sun, H., and Chen, C., Soft Bond-Deformation Paths in Superhard γ-Boron, Phys. Rev. Lett., 2010, vol. 105, art. 215503.
Zhou, X.-F., Tian, Y., and Wang, H.-T., Large Shear Strength Enhancement of Gamma-Boron by Normal Compression, J. Superhard Mater., 2011, vol. 33, no. 6, pp. 401–408.
Mukhanov, V.A., Kurakevych, O.O., and Solozhenko, V.L., The Interrelation between Hardness and Compressibility of Substances and Their Structure and Thermodynamic Properties, ibid., 2008, vol. 30, no. 6, pp. 368–378.
Chen, X.-Q., Niu, H., Li, D., and Li, Y., Modeling Hardness of Polycrystalline Materials and Bulk Metallic Glasses, Intermetallics, 2011, vol. 19, pp. 1275–1281.
Oganov, A.R., Theory of Superhard Materials, In: Comprehensive Hard Materials Review, Elsevier, 2013, Submitted.
Li, K.Y., Wang, X.T., Zhang, F.F., and Xue, D.F., Electronegativity Identification of Novel Superhard Materials, Phys. Rev. Lett., 2008, vol. 100, art. 235504.
Lyakhov, A.O. and Oganov, A.R., Evolutionary Search for Superhard Materials: Methodology and Applications to Forms of Carbon and TiO2, Phys. Rev. B, 2011, vol. 84, art. 092103.
Zhu, Q., Jung, D.Y., Oganov, A.R., Gatti, C., Glass, C.W., and Lyakhov, A.O., Xenon Oxides and Silicates at High Pressures, 2011, Submitted.
Batsanov, S.S., Strukturnaya Khimiya. Fakty i Zavisimosti (Structural Chemistry. Book of Facts), Moscow: Dialogue-MGU, 2000.
Bader, R.F.W., Atoms in Molecules. A Quantum Theory, Oxford: Oxford University Press, 1990.
Heyd, J., Scuseria, G.E., and Ernzerhof, M., Hybrid Functionals Based on a Screened Coulomb Potential, J. Chem. Phys., 2006, vol. 124, art. 219906.
Perdew, J.P., Burke, K. and Ernzerhof, M., Generalized Gradient Approximation Made Simple, Phys. Rev. Lett., 1996, vol. 78, pp. 3865–3868.
Wells, A.F., Structural Inorganic Chemistry, Oxford: Clarendon Press, 1986.
Hayami, W., Theoretical Study of the Stability of AB12 (A = H-Ne) Icosahedral Clusters, Phys. Rev. B, 1999, vol. 60, pp. 1523–1526.
Werheit, H., Luax, M., and Kuhlmann, U., Interband and Gap State Related Transitions in β-Rhombohedral Boron, Phys. Status Solidi B, 1993, vol. 176, pp. 415–432.
Elliott, S.R., The Physics and Chemistry of Solids, New York: John Wiley and Sons, 1998.
Tsirelson, V.G., Evdokimova, O.A., Belokoneva, E.L., and Urusov, V.S., Electron Density Distribution and Bonding in Silicates. A Review of Recent Data, Phys. Chem. Minerals, 1990, vol. 17, pp. 275–292.
Brown, I.D., Chemical and Steric Constraints in Inorganic Solids, Acta Cryst. B, 1992, vol. 48, 553–572.
Edwards, B. and Ashcroft, N.W., Spontaneous Polarization in Dense Hydrogen, Nature, 1997, vol. 388, pp. 652–655.
Ma, Y., Wang, Y., and Oganov, A.R., Absence of Superconductivity in the Novel High-Pressure Polymorph of MgB2. Phys. Rev. B, 2009, vol. 79, art. 054101.
Tsagareishvili, O.A., Chkhartishvili, L.S., and Gabunia, D.L., Apparent Low-Frequency Charge Capacitance of Semiconducting Boron, Semiconductors, 2009, vol. 43, pp. 14–20.
Macchi, P., On the Nature of Chemical Bonding in γ-Boron, J. Superhard Mater., 2011, vol. 33, no. 6, pp. 380–387.
Le Godec, Y., Comparative Review of Theoretical and Experimental Equations of State of Orthorhombic Boron γ-B28, ibid., 2011, vol. 33, no. 6, pp. 388–393.
Rulis, P., Wang, L., Walker, B., and Ching, W.-Y., Spectral Analysis of the Electronic Structure of γ-B28, ibid., 2011, vol. 33, no. 6, pp. 394–400.
Veprek, S., Zhang, R.F., and Argon, A.S., Mechanical Properties and Hardness of Boron and Boron-Rich Solids, ibid., 2011, vol. 33, no. 6, pp. 409–420.
Kurakevych, O.O. and Solozhenko, V.L., Experimental Study and Critical Review of Structural, Thermodynamic and Mechanical Properties of Superhard Refractory Boron Suboxide B6O, ibid., 2011, vol. 33, no. 6, pp. 421–428.
Author information
Authors and Affiliations
Additional information
Original English Text © A.R. Oganov, V.L. Solozhenko, C. Gatti, O.O. Kurakevych, Y. Le Godec, 2011, published in Sverkhtverdye Materialy, 2011, Vol. 33, No. 6, pp. 3–22.
An erratum to this article can be found at http://dx.doi.org/10.3103/S1063457612010108.
About this article
Cite this article
Oganov, A.R., Solozhenko, V.L., Gatti, C. et al. The high-pressure phase of boron, γ-B28: Disputes and conclusions of 5 years after discovery. J. Superhard Mater. 33, 363–379 (2011). https://doi.org/10.3103/S1063457612060019
Received:
Published:
Issue Date:
DOI: https://doi.org/10.3103/S1063457612060019