title: Negative-pressure-induced enhancement in a freestanding ferroelectric.
abstract: Ferroelectrics are widespread in technology, being used in electronics and communications, medical diagnostics and industrial automation. However, extension of their operational temperature range and useful properties is desired. Recent developments have exploited ultrathin epitaxial films on lattice-mismatched substrates, imposing tensile or compressive biaxial strain, to enhance ferroelectric properties. Much larger hydrostatic compression can be achieved by diamond anvil cells, but hydrostatic tensile stress is regarded as unachievable. Theory and ab initio treatments predict enhanced properties for perovskite ferroelectrics under hydrostatic tensile stress. Here we report negative-pressure-driven enhancement of the tetragonality, Curie temperature and spontaneous polarization in freestanding PbTiO3 nanowires, driven by stress that develops during transformation of the material from a lower-density crystal structure to the perovskite phase. This study suggests a simple route to obtain negative pressure in other materials, potentially extending their exploitable properties beyond their present levels.
authors.affiliation: Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.|Graduate School at Shenzhen, Tsinghua University, 518055 Shenzhen, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Wang
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors.forename: Ben
authors.initials: B
authors.lastname: Wylie-van Eerd
authors.affiliation: Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Tomas
authors.initials: T
authors.lastname: Sluka
authors.affiliation: Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Cosmin
authors.initials: C
authors.lastname: Sandu
authors.affiliation: Interdisciplinary Centre for Electron Microscopy, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Marco
authors.initials: M
authors.lastname: Cantoni
authors.affiliation: Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.|Peter Grünberg Institute and Ernst Ruska Center for Microscopy and Spectroscopy with Electrons, Research Center Jülich, 52425 Jülich, Germany.
authors.forename: Xian-Kui
authors.initials: XK
authors.lastname: Wei
authors.affiliation: Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kvasov
authors.affiliation: Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Leo John
authors.initials: LJ
authors.lastname: McGilly
authors.affiliation: Laboratoire Structures, Propriétés et Modélisation des Solides, CNRS-UMR8580, Ecole Centrale Paris, Grande Voie des Vignes 92290 Châtenay-Malabry, France.
authors.forename: Pascale
authors.initials: P
authors.lastname: Gemeiner
authors.affiliation: Laboratoire Structures, Propriétés et Modélisation des Solides, CNRS-UMR8580, Ecole Centrale Paris, Grande Voie des Vignes 92290 Châtenay-Malabry, France.
authors.forename: Brahim
authors.initials: B
authors.lastname: Dkhil
authors.affiliation: Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Alexander
authors.initials: A
authors.lastname: Tagantsev
authors.affiliation: MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, PO Box 600, Wellington 6140, New Zealand.
authors.forename: Joe
authors.initials: J
authors.lastname: Trodahl
authors.affiliation: Ceramics Laboratory, Swiss Federal Institute of Technology (EPFL), 1015 Lausanne, Switzerland.
authors.forename: Nava
authors.initials: N
authors.lastname: Setter