Abstract

<h2>Acta Crystallographica Section B</h2><h3>Structural Crystallography and Crystal Chemistry</h3><h3>0567-7408</h3> <h2>research papers</h2> Volume 38 Part 12 Pages 3009-3011 December 1982 <h2>Atomic positions of three new polytypes of CdI 2 </h2> G. K. Chadha Acta Cryst. (1982). B38, 3009-3011 Atomic Positions of Three New Polytypes of Cdl2 BY G. K. CHADHA Department of Physics and Astrophysics, University of Delhi, Delhi- 110007, India (Received 20 April 1982; accepted 7 July 1982) Abstract The crystal structures of three new polytypes 16H9, 24H8 and 44H~ of cadmium iodide have been determined. The structures are 22(11)6, 2222(211211)z and (22211211)(121121)4 in Zhdanov notation, each with space group P3m 1. All three polytypes have been found syntactically coalesced with other polytypes in three different crystals. Polytype 44H~ is the largest hexagonal polytype of cadmium iodide whose struc- ture has been reported so far. Introduction Extensive work during the last two decades has resulted in the discovery not only of many new polytypes of known substances but also of many new polytypic substances. Not only do these discoveries help in understanding the phenomenon of polytypism more clearly but many new fields, like interpolytypic, intrapolytypic, phase transformation (Tewari & 0567-7408/82/123009-03501.00 Srivastava, 1974), dielectric behaviour of polytypes (Fernandez & Srivastava,