Naslov
Average and local atomic-scale structure in BaZrxTi1−xO3 (x D0:10, 0.20, 0.40) ceramics by high-energy x-ray diffraction and Raman spectroscopy

Autori
Buscaglia, Vincenzo ; Tripathi, Saurabh ; Petkov, Valeri ; Dapiaggi, Monica ; Deluca, Marco ; Gajović, Andreja ; Ren, Yang

Izvornik
Journal of Physics : Condensed Matter (0953-8984) 26 (2014); 065901-1

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
relaxors; BaTiO3; Raman spectroscopy; highenergy

Sažetak
Highresolution xray diffraction (XRD), Raman spectroscopy and total scattering XRD coupled to atomic pair distribution function (PDF) analysis studies of the atomicscale structure of archetypal BaZrxTi1−xO3 (x D0:10, 0.20, 0.40) ceramics are presented over a wide temperature range (100–450 K). For x D0:1 and 0.2 the results reveal, well above the Curie temperature, the presence of Tirich polar clusters which are precursors of a longrange ferroelectric order observed below TC. Polar nanoregions (PNRs) and relaxor behaviour are observed over the whole temperature range for x D0:4. Irrespective of ceramic composition, the polar clusters are due to locally correlated offcentre displacement of Zr=Ti cations compatible with local rhombohedral symmetry. Formation of Zrrich clusters is indicated by Raman spectroscopy for all compositions. Considering the isovalent substitution of Ti with Zr in BaZrxTi1−xO3, the mechanism of formation and growth of the PNRs is not due to charge ordering and random fields, but rather to a reduction of the local strain promoted by the large difference in ion size between Zr4C and Ti4C. As a result, nonpolar or weakly polar Zrrich clusters and polar Tirich clusters are randomly distributed in a paraelectric lattice and the longrange ferroelectric order is disrupted with increasing Zr concentration.

Izvorni jezik
Engleski

Znanstvena područja
Fizika

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