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- Title
Structural characterization of A-site nonstoichiometric (1 − x)Bi<sub>0.5</sub>Na<sub>0.5</sub>TiO<sub>3</sub>-xBaTiO<sub>3</sub> ceramics.
- Authors
Prasertpalichat, Sasiporn; Siritanon, Theeranun; Nuntawong, Noppadon; Cann, David P.
- Abstract
Lead-free 1 − x(Bi0.5Na0.5TiO3)-xBaTiO3, x = 0.055, 0.06 and 0.07, ceramics [i.e., near the morphotropic phase boundary (MPB)] were modified by varying the A-site cation stoichiometry to induce acceptor and donor doping through the addition of excess Na and Bi, respectively. The role of A-site nonstoichiometry on the crystal structure was investigated by using Raman spectroscopy and high-energy X-ray diffraction (XRD) techniques. The Raman spectra were analyzed via spectral deconvolution, and the resultant fitted data demonstrated deviations in the dominant bands (at 200-400 cm−1 and 400-600 cm−1) which indicated a shift toward tetragonal distortions in all Na-excess samples. High-energy XRD data showed that all the characteristic peaks corresponding to tetragonal P4bm structure became more prominent in Na-excess sample. Rietveld refinement data confirmed the coexistence of rhombohedral (R3c) and tetragonal (P4bm) phases with a significant increase in P4bm phase fraction in Na-excess composition. The clear agreements between Raman spectroscopy and high-energy XRD data suggest that Bi-excess samples (i.e., donor doping) had little or no effect on crystal structure, whereas Na-excess samples (i.e., acceptor doping) had a significant influence on the structure near the MPB such that tetragonal distortions were induced in both the local structure and the long-range average structure.
- Subjects
NONSTOICHIOMETRIC compounds; DOPING agents (Chemistry); X-ray diffraction; CRYSTAL structure; RAMAN spectroscopy; RIETVELD refinement
- Publication
Journal of Materials Science, 2019, Vol 54, Issue 2, p1162
- ISSN
0022-2461
- Publication type
Article
- DOI
10.1007/s10853-018-2939-3