The crystal structure of Ni–Zn co-doped β boron, Ni0.18Zn1.21B34.94

The crystal structure of beta-rhombohedral boron co-doped with nickel and zinc was refined using a single crystal of the composition Ni44.4Zn11.2B44.4 (in at.%) (space group, R3¯m, a = 1.10182(2) nm, c = 2.40534(5) nm, RF = 0.040, residual electron density <1.59 e−/Å3). The Ni/Zn ratio of 1:6.5 was determined by electron microprobe analysis. Zn atoms were found to partially occupy atomic sites that have been named E positions in earlier works. A1, D and Dd positions are partially occupied with mixtures of zinc and nickel atoms (Ni:Zn = 15.5:84.5). Refinement in the space group R3 was tried to allow for further ordering of the metal atoms but did not result in a better structure description.

Unit cell for β-rhombohedral boron in perspective view. (a) Interconnected B12 units along with Ni and Zn atoms. (b) Boron network made of B28 units (three icosahedra sharing a common triangle of boron atoms). Zn1 atoms are residing in the E void, P (0.414Zn2 + 0.075Ni1) in A1-void, Q (0.254Zn3 + 0.047Ni2) in D-void and R (0.102Zn4 + 0.019Ni3) in Dd-void.Figure optionsDownload as PowerPoint slideHighlights
► We studied the crystal chemistry of Ni–Zn co-doped β boron Ni0.18Zn1.21B34.94.
► A single crystal for X-ray analysis was obtained from self-flux.
► Zn atoms reside in the E void (occupancy of 33%).
► Random mixtures of Ni, Zn atoms (ratio 15.5:84.5) occupy the sites A1, D and Dd.
► We made a conversion table from non-standardized to standardized atom site labels.