Redetermination of the perovskite-type compound YRh3B revealing a Rh deficiency

In contrast with previous structural studies of ytterbium trirhodium boride, YbRh3B, that suggest a boron deficiency, the current redetermination of the crystal structure of YbRh3B revealed instead a rhodium deficiency with a refined composition of YbRh2.67 (2)B. In the ABX 3 perovskite-type structure, Yb, B and Rh are located on the A, B and X positions, respectively, with site symmetries of m m for the A and B sites, and 4/mm.m for the X site.

In contrast with previous structural studies of ytterbium trirhodium boride, YbRh 3 B, that suggest a boron deficiency, the current redetermination of the crystal structure of YbRh 3 B revealed instead a rhodium deficiency with a refined composition of YbRh 2.67 (2) B. In the ABX 3 perovskite-type structure, Yb, B and Rh are located on the A, B and X positions, respectively, with site symmetries of m3m for the A and B sites, and 4/mm.m for the X site.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: WM2195). deficiency for the boron site. For a closer inspection of this assumption and since anisotropic displacement factors were not reported in the original study, we decided to re-determine the structure of YbRh 3 B and present the results of the structure analysis in this communication.
In the ABX 3 perovskite-type structure, Yb, B and the partly occupied Rh atoms are located on the A, B and X positions, respectively, with site symmetries of m3m for the A and B sites and 4/mm.m for the X site.

Experimental
Single crystals were grown using a flux method with copper as the solvent. Stoichiometric quantities of Yb, Rh and B were mixed with copper in a ratio of about 1:8 by weight. The mixture was heated in a high purity alumina crucible by electric furnace under a purified He gas flow at a rate of about 400 Kh -1 . The sample was kept at a temperature between 1523 and 1623 K for 10 h and cooled at a rate of 1 Kh -1 to 353 K. Then the furnace was cooled rapidly to room temperature. The boride crystals were separated from the copper by treatment with hot nitric acid. The sample was cut into small pieces and was finally ground into a sphere with 41 µm radius by a wind pressure granulation machine with diamond paste.
Contour lines are at intervals of 0.5 e Å -3 . Zero contours are drawn as thick lines, positive contours are drawn as thin lines, negative contours are drawn as broken lines.