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Licensed Unlicensed Requires Authentication Published by De Gruyter (O) September 25, 2009

Crystal structure and optical properties of the new 8O polytype of Ca2Ta2O7

Stefan G. Ebbinghaus, Andreas Kalytta, Jürgen Kopf, Anke Weidenkaff and Armin Reller

Abstract

Single crystals of the new 8O modification of Ca2Ta2O7 were grown by optical floating zone melting and their structure was solved by X-ray diffraction. 8O Ca2Ta2O7 crystallizes in space group C2221 with a = 7.3690(2) Å, b = 12.7296(3) Å, c = 48.263(1) Å. The structure is related to the weberite structure type and can be described as a stacking of 8 basic building units per unit cell. Each building unit consists of one Ta3Ca and one Ca3Ta layer with a cubic close packed arrangement. Transmission measurements in the UV-Vis and IR region reveal a high transparency in a wide energy range from 0.2–3.5 eV. Dielectric measurements yield a high ɛ′ value of 60 at room temperature.

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Published Online: 2009-9-25
Published in Print: 2005-3-1

© 2005 Oldenbourg Wissenschaftsverlag GmbH

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