title: Synthesis, structure and magnetic properties of nanocrystalline YMnO3.
abstract: Nanocrystalline YMnO(3) has been prepared by wet chemical synthesis routes to obtain crystallites with sizes from 20 nm to bulk material. The crystal structure of hexagonal YMnO(3) nanocrystallites smaller than 80 nm deviates from bulk material in terms of unit cell distortion and unit cell volume. The ferrielectric displacements of Y(3+) cations along the polar c-axis decays progressively with decreasing size below 100 nm. Indications of weak ferromagnetism in the form of a narrow hysteresis loop and enhanced magnetic susceptibility below 43 K in 20 nm YMnO(3) nanoparticles is attributed to extrinsic effects. Low-temperature annealing of the 20 nm crystallites in an oxidizing atmosphere removed all traces of ferromagnetism, showing that this is not a size-induced property. Finally, formation of the competing metastable orthorhombic phase and the thermodynamically stable hexagonal phase is discussed with respect to oxidizing or reducing conditions during synthesis.
authors.affiliation: Department of Materials Science and Engineering, Norwegian University of Science and Technology, N-7491, Trondheim, Norway.
authors.forename: Kristin
authors.initials: K
authors.lastname: Bergum
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Okamoto
authors.forename: Helmer
authors.initials: H
authors.lastname: Fjellvåg
authors.forename: Tor
authors.initials: T
authors.lastname: Grande
authors.forename: Mari-Ann
authors.initials: MA
authors.lastname: Einarsrud
authors.forename: Sverre M
authors.initials: SM
authors.lastname: Selbach