La2O2S structure refinement and crystal field
Abstract
<h2>Acta Crystallographica Section B</h2><h3>Structural Crystallography and Crystal Chemistry</h3><h3>0567-7408</h3> <h2>short communications</h2> Volume 29 Part 11 Pages 2647-2648 November 1973 <h2>La 2 O 2 S structure refinement and crystal field</h2> B. Morosin Acta Cryst. (1973). B29, 2647 LazO2S structure refinement and crystal field.* By B. MOROSIN, Sandia Laboratories, Albuquerque, New Mexico 87115, U.S.A. and D. J. NEWMAN, Department of Physics, Queen Mary College, Mile End Road, London E1 4NS, England (Received 9 July 1973; accepted 30 July 1973) Parameters on the structure of La202S have been refined by the least-squares method using 396 Mo Kct intensity data. In space group P3ml, the La3+ ion occupies 3(m) sites surrounded below by three S2- ions (3.037 A) and above by three O2- ions (2.424 A) and one axial 02- ion (2.423/~). A new crystal-field analysis has been performed using this data. Introduction The rare-earth oxysulfides activated with trivalent rare- earth ions form an important technological class of mate- rials with high luminous efficiency (Struck & Fonger, 1971 ; Dobrov & Buchanan, 1972). In particular, neodymium- activated lanthanum oxysulfide, La202S:Nd, has received some attention as a promising new high-gain laser material and, hence, has stimulated studies on the growth of the required single