Original scientific paper

Disordered Microtwinned (Sc_1-x)Sc₄Co₆Sn₁₈ (x = 0.14)

Bogdan Ya. Kotur orcid.org/0000-0002-7326-5822 ; Department of Inorganic Chemistry, The Ivan Franko State University of Lviv, Kyryla & Mefodiya Str. 6, UA–290005 Lviv, Ukraine
Radovan Černý ; Laboratoire de Cristallographie, Université de Genève, 24, quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland

Abstract

The crystal structure and composition of (Sc_1-x)Sc₄Co₆Sn₁₈ (x = 0.14) were refined from single crystal X-ray diffraction data. The structure is disordered microtwinned tetragonal, I4₁/acd, a = 13.341(8), c = 26.69(2) Å, V = 4749.8 Å3, Z = 8, D_x = 7.58 g cm-3, M_r = 2708.5, μ = 23.85 mm-1, 73 refined parameters, R = 0.0638 for 1639 observed unique reflections with F₀ > 4σ(F₀). The title compound belongs to a large series of stannides with formula (M_1-xSn_x)-M₄M'₆Sn₁₈ (M = rare earth, M’ = Co, Ru, Rh, Ir, Os) and two related structures (tetragonal phase II with cell parameters a ≈ 13.7, c ≈27.4 Å and pseudo-cubic phase IF (earlier sometimes called phase III) with a ≈ 13.7 Å, which was explained as microtwinned phase II). The crystal was microtwinned. The refined volume fractions of three twin domains were 0.381(7), 0.287(7) and 0.332(7), respectively. A microtwinning of phase II seems to be an intrinsic feature of its structure thus reducing the probability of the forma-tion of the ideal cubic structure IF during the crystal growth.

Keywords

scandium; rare earths; stannides; intermetallic compounds; crystal chemistry; twinning

Hrčak ID:

132176

URI

https://hrcak.srce.hr/132176

Publication date:

1.9.1999.

Visits: 980 *