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Neutron Diffraction Investigation of Langanite Crystals |
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| Authors: | Kuz’micheva G M Kaurova I A Rybakov V B Dubovsky A B Cousson A Zaharko O |
| Institution: | 1.Lomonosov State Academy of Fine Chemical Technology, Moscow, 119571, Russia ;2.Moscow State University, Moscow, 119992, Russia ;3.Moscow State Open University, Aleksandrov, Moscow oblast, 601655, Russia ;4.Laboratoire Leon Brillouin, Cea/Saclay, 91191, Gif-sur-Yvette Cedex, France ;5.Laboratory for Neutron Scattering, ETZ Zurich & Paul Scherrer Institute, CH 5332, Villigen PSI, Switzerland ; |
| Abstract: | The upper and lower parts of a single crystal with a nominal composition La3Ga5.5Nb0.5O14grown by the Czochralski method (Ir crucible, 99%Ar + 1%O2, growth direction) have been studied by neutron diffraction for the first time. The compositions of the upper and lower parts are found to differ ((La2.935(2)□0.065)(Ga0.450Nb0.550(3))Ga3(Ga1.965(4) □0.035)(O13.90(1) □0.10) and (La2.940(1) □0.060)(Ga0.590Nb0.410(2))Ga5(O13.82(1) □0.18), respectively), and microtwin formation was observed in the upper part, with two unit cells related by the translation 1/2Z. Based on a comparison of the refined crystal composition and optical transmission spectra, the absorption bands at 30 000, 24 500, and 20 500 cm-1 were assigned to divacancies (2 V La', 3 V O..), oxygen vacancies, and color centers, respectively. A relationship between the crystal color and oxygen content is established. |
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