title: Unfolding grain size effects in barium titanate ferroelectric ceramics.
abstract: Grain size effects on the physical properties of polycrystalline ferroelectrics have been extensively studied for decades; however there are still major controversies regarding the dependence of the piezoelectric and ferroelectric properties on the grain size. Dense BaTiO3 ceramics with different grain sizes were fabricated by either conventional sintering or spark plasma sintering using micro- and nano-sized powders. The results show that the grain size effect on the dielectric permittivity is nearly independent of the sintering method and starting powder used. A peak in the permittivity is observed in all the ceramics with a grain size near 1 μm and can be attributed to a maximum domain wall density and mobility. The piezoelectric coefficient d33 and remnant polarization Pr show diverse grain size effects depending on the particle size of the starting powder and sintering temperature. This suggests that besides domain wall density, other factors such as back fields and point defects, which influence the domain wall mobility, could be responsible for the different grain size dependence observed in the dielectric and piezoelectric/ferroelectric properties. In cases where point defects are not the dominant contributor, the piezoelectric constant d33 and the remnant polarization Pr increase with increasing grain size.
authors.affiliation: 1] School of physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China [2] School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Tan
authors.affiliation: School of physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China.
authors.forename: Jialiang
authors.initials: J
authors.lastname: Zhang
authors.affiliation: School of physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China.
authors.forename: Yanqing
authors.initials: Y
authors.lastname: Wu
authors.affiliation: School of physics, State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100, P. R. China.
authors.forename: Chunlei
authors.initials: C
authors.lastname: Wang
authors.affiliation: Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 040 01 Kosice, Slovakia.
authors.forename: Vladimir
authors.initials: V
authors.lastname: Koval
authors.affiliation: School of Engineering and Applied Science, Aston University, Birmingham B4 7ET, United Kingdom.
authors.forename: Baogui
authors.initials: B
authors.lastname: Shi
authors.affiliation: School of Engineering and Applied Science, Aston University, Birmingham B4 7ET, United Kingdom.
authors.forename: Haitao
authors.initials: H
authors.lastname: Ye
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom.
authors.forename: Ruth
authors.initials: R
authors.lastname: McKinnon
authors.affiliation: 1] School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom [2] Department of Applied Science and Technology, Institute of Materials Physics and Engineering, Corso Duca degli Abruzzi 24, 10129 Torino, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Viola
authors.affiliation: School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London, E1 4NS, United Kingdom.
authors.forename: Haixue
authors.initials: H
authors.lastname: Yan