Structural variety beyond appearance: high-pressure phases of CrB<sub>4</sub>in comparison with FeB<sub>4</sub>

Zhang, Yunkun; Wu, Lailei; Wan, Biao; Zhao, Yan; Gao, Rui; Li, Zhiping; Zhang, Jingwu; Gou, Huiyang; Mao, Ho‐kwang

doi:10.1039/c5cp06745f

Cited by 16 publications

(12 citation statements)

References 48 publications

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“…In comparison to diamond and boron nitride ( c ‐BN), the transition metal borides (TMBs) are attractive potential superhard materials because of the network and shorter covalent bonding such as BB covalent bond and TMB bond . Diborides (TMB 2 ) and transition metal tetraborides (TMB 4 ) have been widely investigated over the last years . However, the reported Vickers hardness of TMB 2 or TMB 4 is difficult to meet the requirement of superhard material .…”

Section: Introductionmentioning

confidence: 99%

Influence of alloying elements on the mechanical and thermodynamic properties of ZrB₁₂ceramics from first‐principles calculations

Pan

Lin

2020

Int J of Quantum Chemistry

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Although ZrB 12 is a promising advanced material because of the boron cuboctahedron cages, the hardness of ZrB 12 remains controversy. Here, we apply first-principles calculations to study the influence of transition metals (4d-and 5d-) on the hardness and thermodynamic properties of ZrB 12 . The calculated hardness of ZrB 12 is 32.9 GPa, which is in good agreement with the previous theoretical result. Importantly, the calculated hardness of Re-doped ZrB 12 is up to 40.0 GPa, which is a potential superhard material. The essential reason is that the alloying element of Re enhances the localized hybridization of B B and Zr B atoms, and then forms the strong B B covalent bond and Zr B bond. The result is well demonstrated by the chemical bonding and lattice parameter. Here, our work shows that the alloying elements of Nb, Mo, and Re enhance the thermodynamic properties of ZrB 12 . The Debye temperature of Re-doped ZrB 12 is 1225.2 K, which is larger than that of the parent ZrB 12 (1213.5 K). K E Y W O R D S borides, elastic modulus, first-principles calculations, hardness, thermodynamic properties, ZrB 12 1 | INTRODUCTION Hard and superhard materials (≥40 GPa) are very important industrial materials, which are widely used in various industrial applications because of their high hardness, ultracompressibility, high melting point, and excellent thermal stability etc. [1-10] In comparison to diamond and boron nitride (c-BN), the transition metal borides (TMBs) are attractive potential superhard materials because of the network and shorter covalent bonding such as B B covalent bond and TM B bond. [11][12][13][14][15][16][17][18][19] Diborides (TMB 2 ) and transition metal tetraborides (TMB 4 ) have been widely investigated over the last years. [20][21][22][23][24] However, the reported Vickers hardness of TMB 2 or TMB 4 is difficult to meet the requirement of superhard material. [25][26][27][28][29] Naturally, the Vickers hardness of TMBs mainly relies on the shorter and network covalent bonds. In other words, the high concentration of boron plays a crucial role in Vickers hardness of TMBs. Among these TMBs, it is obvious that the transition metal dodecaborides (TMB 12 ) are potential superhard materials in comparison to TMB 2 and TMB 4 .Recently, ZrB 12 has evoked great interest because of the high concentration of boron and the network B B covalent bonds. [30] This dodecaboride is composed of the boron cuboctahedron cage (24 atoms) and 12-coordinate transition metals at the center of cubic structure. This structural feature is possible to enhance the Vickers hardness of TMBs. However, the Vickers hardness of ZrB 12 remains controversy. Korozlu et al. have found that the calculated Vickers hardness of ZrB 12 is 40.1 GPa, which is believed to a potential superhard material. [31] However, the recent works have shown that the Vickers hardness of ZrB 12 is 35.4 GPa by Chen et al. [32] and 29.3 GPa by Li et al., [33] which are different from Korozlu's result. On the other hand, even if the Vickers hardness of ZrB 12 remains...

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Section: Introductionmentioning

confidence: 99%

Influence of alloying elements on the mechanical and thermodynamic properties of ZrB₁₂ceramics from first‐principles calculations

Pan

Lin

2020

Int J of Quantum Chemistry

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“…The C 22 value for Fe 2 B 7 is 691 GPa, slightly lower than that of Pnnm-FeB 4 (717 GPa). 39 For all three compounds TM 2 B 7 (TM ¼ Fe, Ru and Os), C 22 is much larger than C 11 and C 33 , similar to that in VB 4 20 and higher than the experiment value of Pnnm-FeB 4 (252 GPa). 18 Although the valence electron density of element Ru and Os is higher than that of Fe, the bulk modulus of Ru 2 B 7 and Os 2 B 7 is only 264 GPa and 272 GPa, respectively, suggesting that the valence electron density is not a predominant factor accounting for the bulk moduli of TM 2 The dynamical stability of the newly proposed Ru 2 B 7 and Os 2 B 7 is checked by calculating the phonon spectra (see ESI Fig.…”

Section: Resultsmentioning

confidence: 72%

Revealing phase relations between Fe₂B₇and FeB₄and hypothetical Fe₂B₇-type Ru₂B₇and Os₂B₇: first-principles calculations

Zhang

Wan

et al. 2017

RSC Adv.

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“…The semiconducting FeB 4 and OsB 4 phases offering potential hard properties are contributed by the strong directional covalent bondings of three-dimension (3D) boron networks and the significant covalency of TM–B pairs. While theoretically compressing CrB 4 which starts by the identical Pnnm phase with FeB 4 , it did not encounter the high-pressure semiconducting phase . It is important to remark that Fe and Os are in the group of 8B element in the periodic table that share an analogous electronic configuration, as a result of the related transformation pathway under the high pressure of FeB 4 and OsB 4 .…”

Section: Introductionmentioning

confidence: 96%

“…While theoretically compressing CrB 4 which starts by the identical Pnnm phase with FeB 4 , it did not encounter the highpressure semiconducting phase. 13 It is important to remark that Fe and Os are in the group of 8B element in the periodic table that share an analogous electronic configuration, as a result of the related transformation pathway under the high pressure of FeB 4 and OsB 4 .…”

Section: ■ Introductionmentioning

confidence: 99%

Structural Phase Transitions, Electronic Properties, and Hardness of RuB₄ under High Pressure in Comparison with FeB₄ and OsB₄

et al. 2020

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We have employed an evolutionary algorithm with first-principles calculations to investigate the pressure-induced structural evolution of RuB4 up to 500 GPa. The ambient phase is predicted to be a hexagonal structure (P63/mmc). The novel phases consisting of monoclinic (C2/c) and orthorhombic (Immm) structures are proposed to be the high-pressure phases at the pressure intervals of 198–388 GPa and beyond 388 GPa, respectively. The stability of the predicted phases is confirmed by both dynamic and elastic calculations. The electronic and mechanical properties of the predicted phases are evaluated and mainly discussed compared to the isoelectronic metal tetraborides, i.e., FeB4 and OsB4. In contrast to FeB4 and OsB4, all the stable phases of RuB4 are metal or semimetal, and any semiconducting phases do not emerge in the transformation pathway of RuB4. The nature of chemical bonding investigated by ELF, MPA, and pCOHP calculations reveals that the atomic configurations and the degree of covalent bonding of the predicted phases are responsible for lower hardness compared to those of FeB4 and OsB4. The results of this work provide more understanding of the family of metal tetraboride for designing metal-boride-based hard/superhard materials.

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Structural variety beyond appearance: high-pressure phases of CrB₄in comparison with FeB₄

Cited by 16 publications

References 48 publications

Influence of alloying elements on the mechanical and thermodynamic properties of ZrB₁₂ceramics from first‐principles calculations

Influence of alloying elements on the mechanical and thermodynamic properties of ZrB₁₂ceramics from first‐principles calculations

Revealing phase relations between Fe₂B₇and FeB₄and hypothetical Fe₂B₇-type Ru₂B₇and Os₂B₇: first-principles calculations

Structural Phase Transitions, Electronic Properties, and Hardness of RuB₄ under High Pressure in Comparison with FeB₄ and OsB₄

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Structural variety beyond appearance: high-pressure phases of CrB4in comparison with FeB4

Cited by 16 publications

References 48 publications

Influence of alloying elements on the mechanical and thermodynamic properties of ZrB12ceramics from first‐principles calculations

Influence of alloying elements on the mechanical and thermodynamic properties of ZrB12ceramics from first‐principles calculations

Revealing phase relations between Fe2B7and FeB4and hypothetical Fe2B7-type Ru2B7and Os2B7: first-principles calculations

Structural Phase Transitions, Electronic Properties, and Hardness of RuB4 under High Pressure in Comparison with FeB4 and OsB4

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Structural variety beyond appearance: high-pressure phases of CrB₄in comparison with FeB₄

Influence of alloying elements on the mechanical and thermodynamic properties of ZrB₁₂ceramics from first‐principles calculations

Influence of alloying elements on the mechanical and thermodynamic properties of ZrB₁₂ceramics from first‐principles calculations

Revealing phase relations between Fe₂B₇and FeB₄and hypothetical Fe₂B₇-type Ru₂B₇and Os₂B₇: first-principles calculations

Structural Phase Transitions, Electronic Properties, and Hardness of RuB₄ under High Pressure in Comparison with FeB₄ and OsB₄