Single crystal X-ray analysis of YGex compounds (1

Abstract

The structures of the Y3Ge4, YGe1.82 and YGe2.69 compounds are refined from X-ray single-crystal data. Y3Ge4 is isotypic with Er3Ge4. YGe1.82 (isotypic with ErGe1.83) and YGe2.69 (isotypic with DyGe3) compounds are both characterized by the occurrence of germanium vacancies which are localized, at random within AlB2 slabs or, in a double layer of Ge atoms, respectively. In the latter case, very weak unindexed additional diffracted intensities in the Weissenberg patterns suggest a long-range ordering of these vacancies. Single crystal studies of several AlB2- and ThSi2-types YGe≤2 derivatives clearly evidence large supercells which should also be related to various orderings of the Ge vacancies.