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Journal of Materials
Volume 2013 (2013), Article ID 191626, 6 pages
http://dx.doi.org/10.1155/2013/191626
Research Article

Growth and Neutron Diffraction Investigation of Ca3NbGa3Si2O14 and La3Ga5.5Nb0.5O14 Crystals

1Moscow State Open University, 3 Entuziastov Street, Aleksandrov 601655, Russia
2Lomonosov Moscow University of Fine Chemical Technology, 86 Vernadskogo Prospekt, Moscow 119571, Russia
3Lomonosov State University, Vorobyovy Gory, Moscow 119992, Russia
4Laboratoire Leon Brillouin, Cea/Saclay, 91191 Gif-sur-Yvette Cedex, France
5Laboratory for Neutron Scattering, ETZ Zurich & Paul Scherrer Institute (PSI), CH 5232 Villigen, Switzerland

Received 27 November 2012; Accepted 6 February 2013

Academic Editor: Necmettin Maraşlı

Copyright © 2013 I. A. Kaurova et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Langanite (La3Ga5.5Nb0.5O14, growth atmosphere: 99% Ar + 1% O2) and kanigasite (Ca3NbGa3Si2O14, growth atmosphere: 100% Ar) crystals grown by the Czochralski technique in Ir crucibles along <0001> direction have been firstly investigated by neutron diffraction. The difference between the compositions of upper (La2.935(2)0.065)(Ga0.450Nb0.550(3))Ga3(Ga1.965(4)0.035)(O13.90(1)0.10) and lower (La2.940(1)0.060)(Ga0.590Nb0.410(2))Ga5(O13.82(1)0.18) parts of orange langanite crystal was found. It was established that the colorless Ca3NbGa3Si2O14 crystal grown by using the single-crystal charge has the composition (Ca2.950.05(1))NbGa3Si2O14 and is less defective in comparison to the yellow one grown by using the charge prepared by conventional solid-state reaction. For Ca3NbGa3Si2O14 and La3Ga5.5Nb0.5O14 crystals the possibility of microtwin formation (two unit cells connected by the translation: 1/2 z) was revealed for the first time. It was found that the difference between the color of crystals is attributed to the qualitative differentiation of oxygen vacancies.