Synthesis of transition metal borides and their properties

Knyshev, E.A.; Novgorodtsev, V.M.; Plyshevski, U.S.; Kobyakov, V.A.; Stepanova, Z.G.; Svistunov, V. V.; Becketov, A.R.

doi:10.1016/0022-5088(76)90107-7

Cited by 18 publications

(5 citation statements)

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“…The interactions between the alternating layers of metal atoms and boron atoms have a mixed ionic and covalent character. Depending on the identity of the metal atoms, the M–B and B–B bond lengths and bonding strengths vary, leading to dramatic composition-dependent differences in properties. , Metal diborides exhibit a diverse range of remarkable physical properties. ,− For example, several of them have very high melting points, including some that exceed 3000 °C, such as HfB 2 and ZrB 2 which are considered ultrahigh-temperature ceramics (UHTCs). ,, Other examples of remarkable properties exhibited by the metal diborides include high mechanical strength and hardness (Young’s modulus above 480 GPa for ZrB 2 and HfB 2 ), exceptional mechanical performance at temperatures above 1500 °C for ZrB 2 ceramics, high thermal conductivity, resistance to chemical attack, ,, high fracture toughness, high wear resistance, high electrical conductivity, and electrocatalytic activity for the hydrogen evolution reaction . In contrast, MgB 2 has a substantially lower melting temperature of 830 °C but is well known as a superconductor with a transition temperature of 39 K, which ranks among the highest of the conventional superconductors. − …”

Section: Introductionmentioning

confidence: 99%

“…2,3 The metal diborides exhibit a diverse range of remarkable physical properties. 1,[4][5][6] For example, several of them have very high melting points, including some that exceed 3000ºC, such as HfB2 and ZrB2 which are considered ultrahigh temperature ceramics (UHTCs). 1,7,8 Other examples of remarkable properties exhibited by the metal diborides include high mechanical strength and hardness (Young's modulus above 480 GPa for ZrB2 and HfB2), exceptional mechanical performance at temperatures above 1500ºC for ZrB2 ceramics, 9 high thermal conductivity, 10 resistance to chemical attack, 1,11,12 high fracture toughness, 13 high wear resistance, 14 high electrical conductivity, 15 and electrocatalytic activity for the hydrogen evolution reaction.…”

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Exfoliation of Quasi-Two-Dimensional Nanosheets of Metal Diborides

et al. 2021

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The metal diborides are a class of ceramic materials with crystal structures consisting of hexagonal sheets of boron atoms alternating with planes of metal atoms held together with mixed character ionic/covalent bonds. Many of the metal diborides are ultrahigh temperature ceramics like HfB2, TaB2, and ZrB2, which have melting points above 3000ºC, high mechanical hardness and strength at high temperatures, and high chemical resistance, while MgB2 is a superconductor with a transition temperature of 39 K. Here we demonstrate that this diverse family of non-van der Waals materials can be processed into stable dispersions of two-dimensional (2D) nanosheets using ultrasonication-assisted exfoliation. We generate 2D nanosheets of the metal diborides AlB2, CrB2, HfB2, MgB2, NbB2, TaB2, TiB2, and ZrB2, and use electron and scanning probe microscopies to characterize their structures, morphologies, and compositions. The exfoliated layers span up to micrometers in lateral dimension and reach thicknesses down to 2-3 nm, while retaining their hexagonal atomic structure and chemical composition. We exploit the convenient solution-phase dispersions of exfoliated CrB2 nanosheets to incorporate them directly into polymer composites. In contrast to the hard and brittle bulk CrB2, we find that CrB2 nanocomposites remain very flexible and simultaneously provide increases in the elastic modulus and the ultimate tensile strength of the polymer. The successful liquid-phase production of 2D metal diborides enables their processing using scalable low-temperature solution-phase methods, extending their use to previously unexplored applications, and reveals a new family of non-van der Waals materials that can be efficiently exfoliated into 2D forms.The metal diborides are a family of ceramic compounds with the general formula MB2, where M can be a variety of metals from Groups II, IVB and VB such as Hf, Cr, Ti, Zr, Mg, etc.The most common crystal structure for these materials is the AlB2 type, belonging to the P6/mmm space group symmetry, which has the boron atoms in covalently bound hexagonal sheets separated by layers of close-packed metal atoms, 1 as shown in Figure 1a. The interactions between the

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Section: Introductionmentioning

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Exfoliation of Quasi-Two-Dimensional Nanosheets of Metal Diborides

et al. 2021

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“…Despite the scientific and technological interest in the formation of solid solutions, few studies have focused on reliable syntheses [9][10][11][12][13], and only restricted compositions have been evaluated. Nevertheless, some authors have reported the formation of solid solutions during the high-temperature processing of composite materials, including two different transition metal diborides [14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical synthesis of Ti1−xZrxB2 and Ti1−xHfxB2 solid solutions

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et al. 2011

Ceramics International

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“…The modern scientific and technical revolution is responsible for increasing interest and impetus in the search for materials possessing specific and desired properties. The transition metal borides can be classified as highly refractory and corrosion-resisting compounds, 1 and the transition metal compound (Nd 2 Fe 14 B) has been recently applied as a highperformance permanent magnetic material. From a more scientific point of view, the monoborides have INVAR behavior, 2 while the diborides of transition metal have a unique combination of properties such as high melting point, hardness, chemical stability, high thermal conductivity, low electrical resistivity, and low work function.…”

Section: Introductionmentioning

confidence: 99%

Electronic structure, bonding, and ground-state properties of AlB_{2}-type transition-metal diborides

et al. 2001

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The electronic structure and ground state properties of AlB 2 type transition metal diborides TMB 2 ͑TMϭSc, Ti, V, Cr, Mn, Fe, Y, Zr, Nb, Mo, Hf, Ta͒ have been calculated using the self consistent tight-binding linear muffin-tin orbital method. The equilibrium volume, bulk moduli (B 0), pressure derivative of bulk moduli (B 0 Ј), cohesive energy (E coh), heat of formation (⌬H), and electronic specific heat coefficient (␥) are calculated for these systems and compared with the available experimental and other theoretical results. The bonding nature of these diborides is analyzed via the density of states ͑DOS͒ histogram as well as the charge density plots, and the chemical stability is analyzed using the band filling principle. The variation in the calculated cohesive properties of these materials is correlated with the band filling effect. The existence of a pseudogap in the total density of states is found to be a common feature for all these compounds. The reason for the creation of the pseudogap is found to be due to the strong covalent interaction between boron p states. We have made spin polarized calculations for CrB 2 , MnB 2 , and FeB 2 and found that finite magnetic moments exist for MnB 2 and CrB 2 whereas FeB 2 is nonmagnetic.

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Synthesis of transition metal borides and their properties

Cited by 18 publications

References 2 publications

Exfoliation of Quasi-Two-Dimensional Nanosheets of Metal Diborides

Exfoliation of Quasi-Two-Dimensional Nanosheets of Metal Diborides

Mechanochemical synthesis of Ti1−xZrxB2 and Ti1−xHfxB2 solid solutions

Electronic structure, bonding, and ground-state properties of AlB_{2}-type transition-metal diborides

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