title: Role of thermodynamics in the shape transformation of embedded metal nanoparticles induced by swift heavy-ion irradiation.
abstract: Swift heavy-ion irradiation of elemental metal nanoparticles (NPs) embedded in amorphous SiO(2) induces a spherical to rodlike shape transformation with the direction of NP elongation aligned to that of the incident ion. Large, once-spherical NPs become progressively more rodlike while small NPs below a critical diameter do not elongate but dissolve in the matrix. We examine this shape transformation for ten metals under a common irradiation condition to achieve mechanistic insight into the transformation process. Subtle differences are apparent including the saturation of the elongated NP width at a minimum sustainable, metal-specific value. Elongated NPs of lesser width are unstable and subject to vaporization. Furthermore, we demonstrate the elongation process is governed by the formation of a molten ion-track in amorphous SiO(2) such that upon saturation the elongated NP width never exceeds the molten ion-track diameter.
authors.affiliation: Research School of Physics and Engineering, Australian National University, Canberra, Australia.
authors.forename: M C
authors.initials: MC
authors.lastname: Ridgway
authors.forename: R
authors.initials: R
authors.lastname: Giulian
authors.forename: D J
authors.initials: DJ
authors.lastname: Sprouster
authors.forename: P
authors.initials: P
authors.lastname: Kluth
authors.forename: L L
authors.initials: LL
authors.lastname: Araujo
authors.forename: D J
authors.initials: DJ
authors.lastname: Llewellyn
authors.forename: A P
authors.initials: AP
authors.lastname: Byrne
authors.forename: F
authors.initials: F
authors.lastname: Kremer
authors.forename: P F P
authors.initials: PF
authors.lastname: Fichtner
authors.forename: G
authors.initials: G
authors.lastname: Rizza
authors.forename: H
authors.initials: H
authors.lastname: Amekura
authors.forename: M
authors.initials: M
authors.lastname: Toulemonde