Average and local atomic-scale structure in BaZrxTi1-xO3 (x=0.10, 0.20, 0.40) ceramics by high-energy x-ray diffraction and Raman spectroscopy

作者：Buscaglia Vincenzo^*; Tripathi Saurabh; Petkov Valeri; Dapiaggi Monica; Deluca Marco; Gajovic Andreja; Ren Yang

来源：Journal of Physics: Condensed Matter , 2014, 26(6): 065901.

DOI：10.1088/0953-8984/26/6/065901

• relaxors
• BaTiO3
• Raman spectroscopy
• high-energy XRD
• polar nanoregions

High-resolution x-ray diffraction (XRD), Raman spectroscopy and total scattering XRD coupled to atomic pair distribution PDF) analysis studies of the atomic-scale structure of archetypal BaZrxTi1-xO3 (x = 0.10, 0.20, 0.40) ceramics are presented over a wide temperature range (100-450 K). For x = 0.1 and 0.2 the results reveal, well above the Curie temperature, the presence of Ti-rich polar clusters which are precursors of a long-range ferroelectric order observed below TC. Polar nanoregions (PNRs) and relaxor behaviour are observed over the whole temperature range for x = 0.4. Irrespective of ceramic composition, the polar clusters are due to locally correlated off-centre displacement of Zr/Ti cations compatible with local rhombohedral symmetry. Formation of Zr-rich 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 Zr4+ and Ti4+. As a result, non-polar or weakly polar Zr-rich clusters and polar Ti-rich clusters are randomly distributed in a paraelectric lattice and the long-range ferroelectric order is disrupted with increasing Zr concentration.

• 出版日期2014-2-12