High-Pressure Synthesis of β-Ir4B5 and Determination of the Compressibility of Various Iridium Borides

"A new iridium boride, beta-Ir4B5, was synthesized under high-pressure/high-temperature conditions of 10.5 GPa and 1500 degrees C in a multianvil press with a Walker-type module. The new modification beta-Ir4B5 crystallizes in a new structure type in the orthorhombic space group Pnma (no. 62) with the lattice parameters a = 10.772(2) angstrom, b = 2.844(1) angstrom, and c = 6.052(2) angstrom with R1 = 0.0286, wR2 = 0.0642 (all data), and Z = 2. The structure was determined by single-crystal X-ray and neutron powder diffraction on samples enriched in B-11. The compound is built up by an alternating stacking of boron and iridium layers with the sequence ABA'B'. Additionally, microcalorimetry, hardness, and compressibility measurements of the binary iridium borides alpha-Ir4B5, beta-Ir4B5, Ir5B4, hexagonal Ir4B3-x and orthorhombic Ir4B3-x were carried out and theoretical investigations based on density function theory (DFT) were employed to complement a comprehensive evaluation of structure-property relations. The incorporation of boron into the structures does not enhance the compressibility but leads to a significant reduction of the bulk moduli and elastic constants in comparison to elemental iridium.

High-Pressure Synthesis of β\beta-Ir4_4B5_5 and Determination of the Compressibility of Various Iridium Borides

Single-crystals of a new iridium boride modification β-Ir4B5 were obtained by a high-pressure/high-temperature experiment. The structure of the new compound was characterized via X-ray and neutron diffraction. Furthermore, measurements of the compressibility, hardness, and thermodynamical properties of the new phase as well as of various other iridium borides were carried out. Complementary theoretical investigations based on density functional theory (DFT) were employed to confirm our experimental findings

High-Pressure Synthesis of β‑Ir₄B₅ and Determination of the Compressibility of Various Iridium Borides

A new iridium boride, β-Ir₄B₅, was synthesized under high-pressure/high-temperature conditions of 10.5 GPa and 1500 °C in a multianvil press with a Walker-type module. The new modification β-Ir₄B₅ crystallizes in a new structure type in the orthorhombic space group <i>Pnma</i> (no. 62) with the lattice parameters <i>a</i> = 10.772(2) Å, <i>b</i> = 2.844(1) Å, and <i>c</i> = 6.052(2) Å with <i>R</i>1 = 0.0286, <i>wR</i>2 = 0.0642 (all data), and <i>Z</i> = 2. The structure was determined by single-crystal X-ray and neutron powder diffraction on samples enriched in ¹¹B. The compound is built up by an alternating stacking of boron and iridium layers with the sequence ABA′B′. Additionally, microcalorimetry, hardness, and compressibility measurements of the binary iridium borides α-Ir₄B₅, β-Ir₄B₅, Ir₅B₄, hexagonal Ir₄B_3–<i>x</i> and orthorhombic Ir₄B_3–<i>x</i> were carried out and theoretical investigations based on density function theory (DFT) were employed to complement a comprehensive evaluation of structure–property relations. The incorporation of boron into the structures does not enhance the compressibility but leads to a significant reduction of the bulk moduli and elastic constants in comparison to elemental iridium