The Crystal Structure of RuB2, OsB2, and IrB1.35 and Some General Comments on the Crystal Chemistry of Borides in the Composition Range MeB - MeB3.

Aronsson, B.; Leden, Ido; Sunner, Stig; Hatanaka, Akikazu; Munch‐Petersen, Jon

doi:10.3891/acta.chem.scand.17-2036

Cited by 73 publications

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“…A first refinement shows consistency with iridium atoms in two 4i (x, 0, z) sites (both on a mirror plane), however, with rather strong anisotropic atom displacement parameters (ADPs). This structure model (see model 1 in Table 3) is essentially consistent with the one earlier described by Aronsson et al [13]. However, the boron atoms located from our difference Fourier map unambiguously revealed only 3 boron positions (B1, B2, B3) instead of the 4 sites reported by Aronsson et al [13] of which one (B3) was only half occupied.…”

Section: Articlessupporting

confidence: 77%

“…This structure model (see model 1 in Table 3) is essentially consistent with the one earlier described by Aronsson et al [13]. However, the boron atoms located from our difference Fourier map unambiguously revealed only 3 boron positions (B1, B2, B3) instead of the 4 sites reported by Aronsson et al [13] of which one (B3) was only half occupied. A difference Fourier map after isotropic refinement of the iridium atoms and subtracting the contribution of the boron atoms, revealed electron density peaks at ~0.1 Å off the mirror plane (see Fig.…”

Section: Articlessupporting

confidence: 77%

“…The Ir 4 B 5+x phase melts congruently at 1288±4°C (1287±5°C [23], 1313±15°C [9], see Table 1). As has been previously reported [13], this compound is not stable at lower temperatures (T ≤ 1100°C). Indeed DTA effects document the decomposition at 1083±10°C into Ir 5 B 4+x and boron.…”

Section: Articlesmentioning

confidence: 70%

“…For example, W 1−x B 3 possesses a load independent Vickers hardness of 31.8 GPa (but 46.2 GPa at 0.5 N and 36.7 GPa at 1N [2]) and polycrystalline ReB 2 exceeds an average load independent Vickers hardness of about 30 tion [13]. Due to boron defects in two of the four B-sites, a formula of IrB 1.35 was derived.…”

Section: Introductionmentioning

confidence: 99%

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Crystal structures and constitution of the binary system iridium-boron

et al. 2015

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GPa [2] (48 GPa (0.5 N) [3]) or 26.6 GPa (39.3 GPa (0.5 N)) [2] with rather different hardness values due to the anisotropic crystal structure (for details on the crystal structure of W 1−x B 3 , see [4]). Vicker's hardness measurements on the boron richest iridium boride IrB 1.35 revealed a load independent value of 18.2 GPa (at 9.81 N) but 49.8 GPa at 0.49 N [5] and at such low loads the hardness is therefore comparable with bulk samples of ReB 2 . Quite high hardness values were also recorded for IrB 1.1 thin films (on SiO 2 substrate) revealing an intrinsic film hardness of 43(±5) GPa [6].Investigations on the constitution of the binary system Ir-B revealed the existence of three compounds Ir 3 B 2 , IrB and IrB 2 [7−9]. Some of the early reports were mainly concerned with the metal-rich eutectic (1046°C at 21.4 at.% B [10]), with the optimization of synthesis techniques [8] and with the stability of IrB 1.1 against various acids and bases [11]. Melting point (T m = 1190 ± 20°C), microhardness 1652 ± 80 kgf/mm 2 , Seebeck coefficient (20−800°C, S V , min = −9 μV/K at 350°C) and electrical resistance (20−800°C) for IrB 1.1 were reported by Samsonov et al. [8]. X-ray powder and single crystal (Weissenberg) photographs served to evaluate the crystal structure of IrB 1.1 , which was reported to be isotypic with the α-ThSi 2 structure type (space group I4 1 /amd; a = 0.2810, c =1.0263 nm) exhibiting a severe defect at the boron sites (8e sites randomly occupied by ~50% of B atoms) [12]. For the compound richest in boron, 'IrB 2 ' , monoclinic symmetry (space group C2/m) was established from X-ray single crystal multi-film Weissenberg photographs yielding a crystal structure described as a stacking of puckered boron layers (A) and puckered double layers of metal atoms (B) in the simple sequence ABAB in c-direc-

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Section: Articlessupporting

confidence: 77%

Section: Articlessupporting

confidence: 77%

Section: Articlesmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

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Crystal structures and constitution of the binary system iridium-boron

et al. 2015

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“…The obtained lattice constant, bulk modulus B 0 and its pressure derivative B 0 for the Orth and the Hex structures of OsB 2 at zero pressure are listed in Table I. For the Orth structure of OsB 2 the equilibrium lattice parameters obtained are in good agreement with the experimental data [17,18] and other theoretical results [2,3]. The LDA calculations underestimate the lattice constants, while the GGA calculations overestimate the lattice constants.…”

Section: Resultssupporting

confidence: 74%

Thermodynamic and Electronic Properties of OsB₂from First-Principles Calculations

et al. 2014

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The pressure induced phase transitions of OsB2 from the orthorhombic structure (Orth) to the hexagonal structure (Hex) is investigated by using ab initio plane-wave pseudopotential density functional theory, together with quasi-harmonic Debye model. We nd that the pressure-induced phase transition occurs at 2.8 GPa and 12.5 GPa by local density approximation and general gradient approximation, respectively. It is predicted that OsB2 has no phase transition temperature from the Orth structure to the Hex structure. Moreover, the dependences of the relative volume V /V0 on the pressure, thermal expansion coecient α on the pressure and temperature are also successfully obtained. The electronic properties including energy band, total and partial density of states and electron density dierence for two structures are also analyzed. The Mulliken charges and Bond populations for both Orth and Hex structures are also obtained.

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Borides with Two‐Dimensional Boron Networks

Rogl¹

1991

Inorganic Reactions and Methods

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The Crystal Structure of RuB2, OsB2, and IrB1.35 and Some General Comments on the Crystal Chemistry of Borides in the Composition Range MeB - MeB3.

Cited by 73 publications

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Crystal structures and constitution of the binary system iridium-boron

Crystal structures and constitution of the binary system iridium-boron

Thermodynamic and Electronic Properties of OsB₂from First-Principles Calculations

Borides with Two‐Dimensional Boron Networks

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The Crystal Structure of RuB2, OsB2, and IrB1.35 and Some General Comments on the Crystal Chemistry of Borides in the Composition Range MeB - MeB3.

Cited by 73 publications

References 0 publications

Crystal structures and constitution of the binary system iridium-boron

Crystal structures and constitution of the binary system iridium-boron

Thermodynamic and Electronic Properties of OsB2from First-Principles Calculations

Borides with Two‐Dimensional Boron Networks

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Thermodynamic and Electronic Properties of OsB₂from First-Principles Calculations