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Uniaxial birefringence in "cubic" Pb(Fe0.5Ta0.5)O3: is there a hidden symmetry breaking?

Published in Ferroelectrics. 1995, vol. 172, no. 1-4, p. 277-85
Abstract The room temp. phase of the B-site disordered perovskite Pb(Fe0.5Ta0.5)O3 (PFT) was studied by single crystal x-ray diffraction and by polarized light microscopy. While pyramidal (100) growth sectors display a weak birefringence, indicating a tetragonal symmetry with an optically uniaxial pos. indicatrix, the structure of PFT crystals can be well refined in cubic space group Pm.hivin.3m, however, the introduction of disorder on the A site is necessary. In the light of the optical symmetry, the (x00) A-site disordered cubic structure was considered as a mean structure averaged over tetragonal domains, each contg. Pb displaced just towards one of the three [100]cub equiv. directions. Attempts at refinements in tetragonal symmetry and at mech. (ferroelastic) switching of domains are discussed.
Keywords Crystal structure (of iron lead tantalum oxide)Birefringence (uniaxial birefringence in Pb(Fe0.5Ta0.5)O3)Iron lead tantalate structure uniaxial birefringence
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Project FNS: 1994
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GEDDO LEHMANN, Alessandra et al. Uniaxial birefringence in "cubic" Pb(Fe0.5Ta0.5)O3: is there a hidden symmetry breaking?. In: Ferroelectrics, 1995, vol. 172, n° 1-4, p. 277-85. https://archive-ouverte.unige.ch/unige:31178

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Deposited on : 2013-11-20

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