Effect of Ba incorporation on pressure-induced structural changes in the relaxor ferroelectric PbSc0.5Ta0.5O3

Date
2009-09-28Author
Welsch, A. M.
Maier, B. J.
Engel, J. M.
Mihailova, B.
Angel, R. J.
Paulmann, C.
Gospodinov, M.
Friedrich, A.
Stosch, R.
Guttler, B.
Petrova, D.
Bismayer, U.
Metadata
Show full item recordAbstract
Pressure-induced structural changes in the canonical relaxor Pb0.78Ba0.22Sc0.5Ta0.5O3 were studied with both in-house and synchrotron single-crystal x-ray diffraction as well as Raman spectroscopy at pressures up to 9.8 GPa. The results reveal that the substitution of Ba for Pb in ABO(3) perovskite-type structures, i.e., the substitution of a two-valent element with an isotropic electron shell for an isovalent element with a stereochemically active lone pair, leads to a "diffuse pressure-induced phase transition," a structural transformation over a broad pressure range, without a well-defined critical pressure point. The smeared phase transition of the average structure results from the existence of local structural deformations in the vicinity of A-positioned Ba cations.