Structural evolution induced by acceptor doping into BaTiO 3 ceramics

• Published in: Journal of alloys and compounds Vol. 508; no. 2; pp. 486 - 493
• Main Authors: Wei, X.K., Zhang, Q.H., Li, F.Y., Jin, C.Q., Yu, R.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2010
• Subjects: Crystal and ligand fields; Ferroelectrics; Scanning electron microscopy; Transmission electron microscopy; X-ray diffraction; 68.37.Lp; Scanning electron microscopy; 77.84.−s; Transmission electron microscopy; X-ray diffraction; Ferroelectrics; Crystal and ligand fields; 61.05.cp
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2010.08.099

▶ Structural phase transition induced by oxygen vacancy and smaller cation substitution is observed in Fe, Mn and Co doped BaTiO 3 ceramics. ▶ Structural incommensurate modulation is observed in the hexagonal Ba(Ti 1− ‘ TM x )O 3− δ (TM = Fe, Mn and Co) systems. ▶ Rhombohedral Ba(Ti 1/3Mn 2/3)O 3− δ characterized by face-sharing prism corner-connected by oxygen atoms is discovered. Solid state reaction method is used to synthesize Ba(Ti 1− x TM x )O 3− δ (TM = Fe, Mn and Co) and (Ba 1− y Sr y )(Ti 1/3Fe 2/3)O 3− δ ceramics. The X-ray diffraction, scanning electron microscopy and transmission electron microscopy investigations reveal that structural evolutions from an orthorhombic BaTiO 3 to a hexagonal Ba(Ti 1− x TM x )O 3− δ , a hexagonal to a rhombohedral in Ba(Ti 1− x Mn x )O 3− δ , and a hexagonal to a pseudo-cubic transition in (Ba 1− y Sr y )(Ti 1/3Fe 2/3)O 3− δ are induced by increasing the doping concentration. Due to the oxygen vacancies derived from acceptor doping, nanoscale domains of incommensurate modulation (ICM) resultant are commonly observed in the hexagonal Ba(Ti 1− x TM x )O 3− δ compounds. The newly discovered rhombohedral Ba(Ti 1/3Mn 2/3)O 3− δ having characteristic of face-sharing prism corner-connected by oxygen atoms is a typical example in searching for novel multiferroics. Discrepancies between the ionic radii of the B- and A-site dopants and that of Ti and Ba as a function of the doping concentrations, i.e., the effects of oxygen vacancies and the electronic configurations of the dopants, are concluded to be the driving forces for the structural transitions.