title: Ultrasmall Yttrium Iron Garnet Nanoparticles with High Coercivity at Low Temperature Synthesized by Laser Ablation and Fragmentation of Pressed Powders.
abstract: Pulsed laser ablation of pressed yttrium iron garnet powders in water is studied and compared to the ablation of a single-crystal target. We find that target porosity is a crucial factor, which has far-reaching implications on nanoparticle productivity. Although nanoparticle size distributions obtained by analytical disc centrifugation and transmission electron microscopy (TEM) are in agreement, X-ray diffraction and energy dispersive X-ray analysis show that only nanoparticles obtained from targets with densities close to that of a bulk target lead to comparable properties. Our findings also show why the gravimetrical measurement of nanoparticle productivity is often flawed and needs to be complemented by colloidal productivity measurements. The synthesized YIG nanoparticles are further reduced in size by laser fragmentation to obtain sizes smaller than 3 nm. Since the particle diameters are close to the YIG lattice constant, these ultrasmall nanoparticles reveal an immense change of the magnetic properties, exhibiting huge coercivity (0.11 T) and irreversibility fields (8 T) at low temperatures.
authors.affiliation: Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstr. 7, 45141, Essen, Germany.
authors.forename: Tim
authors.initials: T
authors.lastname: Schmitz
authors.affiliation: Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Lotharstr. 1, 47057, Duisburg, Germany.
authors.forename: Ulf
authors.initials: U
authors.lastname: Wiedwald
authors.affiliation: INNOVENT e.V. Technologieentwicklung, Prüssingstr., 27B, 07745, Jena, Germany.
authors.forename: Carsten
authors.identifier: http://orcid.org/0000-0001-6760-929X
authors.initials: C
authors.lastname: Dubs
authors.affiliation: Technical Chemistry I and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen, Universitaetsstr. 7, 45141, Essen, Germany.
authors.forename: Bilal
authors.identifier: http://orcid.org/0000-0001-6368-9659
authors.initials: B
authors.lastname: Gökce
keywords: magnetic nanoparticles; nanoparticle productivity; pulsed laser ablation in liquids; yield; yttrium iron garnet