A refinement of the structure of barium tantalum oxide, Ba5Ta4O15
Abstract
<h2>Acta Crystallographica Section B</h2><h3>Structural Crystallography and Crystal Chemistry</h3><h3>0567-7408</h3> <h2>research papers</h2> Volume 26 Part 2 Pages 102-105 February 1970 <h2>A refinement of the structure of barium tantalum oxide, Ba 5 Ta 4 O 15 </h2> J. Shannon and L. Katz Acta Cryst. (1970). B26, 102 A Refinement of the Structure of Barium Tantalum Oxide, BasTaaO,s BY JOSEPH SHANNON AND LEWIS KATZ Department of Chemistry and Institute of Materials Science, University of Connecticut, Storrs, Connecticut, U.S.A. (Received 30 January 1969) The five-layer structure previously reported for BasTa4015 has been confirmed. An isotropic structure refinement was carried out with 253 counter-recorded reflections larger than 2a for their background to a conventional R value of 5"7%. Anomalous dispersion, absorption, and secondary extinction cor- rections were made. The space group is P-3ml ; cell dimensions are a = 5.776 _+ 0.005, e = 11"82 _+ 0.01/~, and there is one formula unit per cell. The octahedral environments of the tantalum atoms are dis- torted in a manner consistent with the requirements of local charge balance. The shortest Ta-O dis- tances in the octahedra are 1"86+ 0.02 A, the longest are 2.22+ 0.03 A. The shortest Ba-O distance is 2-64+0-03 ~. Introduction The preparation