title: Large Flexoelectric Anisotropy in Paraelectric Barium Titanate.
abstract: The bending-induced polarization of barium titanate single crystals has been measured with an aim to elucidate the origin of the large difference between theoretically predicted and experimentally measured flexoelectricity in this material. The results indicate that part of the difference is due to polar regions (short-range order) that exist above T(C) and up to T*≈200-225 °C. Above T*, however, the flexovoltage coefficient still shows an unexpectedly large anisotropy for a cubic material, with (001)-oriented crystals displaying 10 times more flexoelectricity than (111)-oriented crystals. Theoretical analysis shows that this anisotropy cannot be a bulk property, and we therefore interpret it as indirect evidence for the theoretically predicted but experimentally elusive contribution of surface piezoelectricity to macroscopic bending-induced polarization.
authors.affiliation: ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona), Spain.|CSIC-Consejo Superior de Investigaciones Cientificas, ICN2 Building, Campus UAB, 08193 Bellaterra (Barcelona), Spain.
authors.forename: Jackeline
authors.initials: J
authors.lastname: Narvaez
authors.affiliation: ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona), Spain.
authors.forename: Sahar
authors.initials: S
authors.lastname: Saremi
authors.affiliation: Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
authors.forename: Jiawang
authors.initials: J
authors.lastname: Hong
authors.affiliation: Institut de Ciencia de Materials de Barcelona (ICMAB-CSIC), Campus UAB, 08193 Bellaterra (Barcelona), Spain.|ICREA-Institucio Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain.
authors.forename: Massimiliano
authors.initials: M
authors.lastname: Stengel
authors.affiliation: ICN2-Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona), Spain.|ICREA-Institucio Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain.
authors.forename: Gustau
authors.initials: G
authors.lastname: Catalan