MX2 compounds of thorium and the polymorphism of thorium disilicide
Abstract
<h2>Acta Crystallographica</h2><h3></h3><h3>0365-110X</h3> <h2>research papers</h2> Volume 14 Part 8 Pages 860-865 August 1961 <h2>MX 2 compounds of thorium and the polymorphism of thorium disilicide</h2> A. Brown Acta Cryst. (1961). 14, 860 MX2 Compounds of Thorium and the Polymorphism of Thorium Disilicide BY ALLA~ BROW~* The General Electric Company Limited, Hirst Research Centre, Wembley, E~wland (Received 26 September 1960 and in revised form 24 November 1960) The crystal structures of phases with the composition ThXe have been examined using X-ray powder and single-crystal techniques. Where X is Ni, Cu, Ag, Au, Zn, Cd, A1 or Si (fl-ThSi2) crystal struc- tures of the C32-type are found. Where X is Si (a-ThSi2) or Ga, the structures are of the Cc type. Related non-stoiehiometrie phases are ThSil.6~ (defect C32-type), ThGel.5 (distorted, defect C32- type) and ThG%.62 (defect Cc type). Stoichiometric ThGe2 has an A-face-centred orthorhombic structure. Consideration of these phases suggests that their crystal structures are influenced by the atomic radius r and the valency e of the X atom. Low values of e. r are reflected in crystal structures of the C32-type. Si has a critical value of e.r and ThSie is dimorphic. Ge has the highest value of e.r and ThGe2