Journal Article

FZJ-2023-01374

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Combined X-ray and Neutron Powder Diffraction Study on B-site Cation Ordering in Complex Perovskite La2(Al1/2MgTa1/2)O6

Sohn, Y. J. (Corresponding author)FZJ* ; Baran, V. ; Gilles, R. ; Roth, G. ; Vassen, R.FZJ*

2023
MDPI Basel

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Please use a persistent id in citations: http://hdl.handle.net/2128/34066  doi:10.3390/solids4010006

Abstract: Complex perovskite La2(Al1/2MgTa1/2)O6 (LAMT) crystallizes in a monoclinic unit cell with space group P21/n at room temperature. Its B-site cations are ordered in a rock-salt-type arrangement. Previously, the full occupancy of Mg on the 2c-Wyckoff position was deduced from powder X-ray diffraction (PXRD). However, conventional X-rays could not properly resolve the mixed occupation on the B-site, since there is little scattering contrast between the neighbouring elements Mg and Al of the periodic table. Hence, complementary neutron diffraction studies were carried out to verify the exact B-site cation ordering in the unit cell. In this specific configuration of the B-cations, with its occupancy ratio and the presence of a heavy element Ta as well as neighbouring elements Mg and Al, only the strategy of a combined Rietveld analysis using both the X-ray and neutron diffraction data simultaneously succeeded in elucidating an accurate B-site cation ordering in this complex perovskite system. A full occupancy of Mg on the 2c-Wyckoff position and each a half occupancy of Al and Ta on the 2d-Wyckoff position could be resolved for the rock-salt-type ordering of the B-site cations in the monoclinic unit cell of LAMT.

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Contributing Institute(s):

1. Werkstoffsynthese und Herstellungsverfahren (IEK-1)

Research Program(s):

1. 1241 - Gas turbines (POF4-124) (POF4-124)

Appears in the scientific report 2023

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