1 research outputs found
High-Pressure Synthesis of β‑Ir<sub>4</sub>B<sub>5</sub> and Determination of the Compressibility of Various Iridium Borides
A new
iridium boride, β-Ir<sub>4</sub>B<sub>5</sub>, 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-Ir<sub>4</sub>B<sub>5</sub> 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)
Ã…, <i>b</i> = 2.844(1) Ã…, and <i>c</i> = 6.052(2) Ã… 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 <sup>11</sup>B. 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-Ir<sub>4</sub>B<sub>5</sub>, β-Ir<sub>4</sub>B<sub>5</sub>, Ir<sub>5</sub>B<sub>4</sub>, hexagonal Ir<sub>4</sub>B<sub>3–<i>x</i></sub> and orthorhombic Ir<sub>4</sub>B<sub>3–<i>x</i></sub> 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