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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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