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Effect of high pressure on the Pb ( Mg 1 ∕ 3 Nb 2 ∕ 3 ) <mml:…

2004; American Physical Society; Volume: 70; Issue: 13 Linguagem: Inglês

10.1103/physrevb.70.134114

1550-235X

B. Chaabane, J. Kreisel, Pierre Bouvier, G. Lucazeau, Brahim Dkhil,

Multiferroics and related materials

We report a high-pressure Raman scattering investigation of $(1\ensuremath{-}x)\mathrm{Pb}({\mathrm{Mg}}_{1∕3}{\mathrm{Nb}}_{2∕3}){\mathrm{O}}_{3}\text{\ensuremath{-}}x\mathrm{Pb}\mathrm{Ti}{\mathrm{O}}_{3}$ $(\mathrm{PMN}\text{\ensuremath{-}}{\mathrm{PT}}_{x})$, which is considered as a prototype relaxor-based piezoelectric. The observed spectral changes are important and it is the pressure-induced appearance of a sharp band at roughly $370\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}1}$ for all investigated $\mathrm{PMN}\text{\ensuremath{-}}{\mathrm{PT}}_{x}$, that allows the construction of a partial $x\text{\ensuremath{-}}p$ phase diagram which is characterized by a high-pressure non-cubic structure. This high-pressure structure is very similar if not identical to the high-pressure structure of PMN. Finally, we present a discussion of the high-wavenumber part of the Raman spectrum in terms of a two-mode behavior, which suggests a very local order around Ti atoms.