Influence of a co-substituted A-site on structural characteristics and ferroelectricity of (Pb, Ba, Ca)TiO3 complex perovskites: analysis of local-, medium- and long-range order

• Published in: Journal of sol-gel science and technology 2014-03, Vol.69 (3), p.605-616
• Main Authors: Pontes, D. S. L., Pontes, F. M., da Silva, L. F., Chiquito, A. J., Pizani, P. S., Longo, E.
• Format: Article
• Language: English
• Subjects: Calcium ions; Ceramics; Chemistry; Chemistry and Materials Science; Cluster analysis; Colloidal gels. Colloidal sols; Colloidal state and disperse state; Composites; Crystal structure; Dipoles; Exact sciences and technology; Ferroelectric materials; Ferroelectricity; General and physical chemistry; Glass; Infrared analysis; Infrared spectroscopy; Inorganic Chemistry; Lead titanates; Long range order; Materials Science; Nanotechnology; Natural Materials; Optical and Electronic Materials; Organic chemistry; Original Paper; Perovskites; Phase transitions; Silicon dioxide; Silicon substrates; Substitutes; Symmetry; Temperature dependence; Thickness; Thin films; Transition temperature; X ray absorption; X-ray diffraction
• ISSN: 0928-0707; 1573-4846
• DOI: 10.1007/s10971-014-3265-0

Thin films of A-site co-substituted, PbTiO 3 (PTO) by Ba 2+ and Ca 2+ , i.e., PBCT70, PBCT60, PBCT50 and PBCT40 were fabricated on Pt/Ti/SiO 2 /Si substrates by chemical solution deposition. Structures of the samples were investigated from the viewpoint of local-, medium- and long-range order by X-ray absorption near structure (XANES), micro-Raman and infrared spectroscopies and by X-ray diffraction (XRD). The films thickness were determined by using field-emission scanning electron microscope. The experimental results demonstrate that BaO 12 clusters are the critical dominant ferroelectricity cause in PBCT thin films rather than CaO 12 clusters. XRD analysis which was applied to investigate the crystal symmetry indicates the absence of long-range structural distortion for samples at higher concentrations of Ba 2+ and Ca 2+ . However, an analysis of structural medium- and local-range order such as infrared, micro-Raman and XANES spectroscopies revealed that symmetry changes are much more prominent; i.e., local structural distortions remain. Temperature-dependent dielectric permittivity measurements confirmed a decreasing ferroelectric-to-paraelectric phase transition temperature and showed a broad phase transition with an increase in BaO 12 and CaO 12 clusters. In addition, the lack of long-range polar ordering for the ferroelectric dipole caused by symmetry changes decreases the remanent polarization.