title: Assembly behavior of iron oxide-capped Janus particles in a magnetic field.
abstract: Three types of iron oxide Janus particles are obtained by varying the deposition rate of iron in a 3:1 Ar/O(2) atmosphere during physical vapor deposition. Each type of iron oxide Janus particle shows a distinct assembly behavior when an external magnetic field is applied, i.e., formation of staggered chains, double chains, or no assembly. A detailed deposition rate diagram is obtained to identify the relationship between deposition rate and assembly behavior. The extent of iron oxidation is identified as the key parameter in determining the assembly behavior. In addition, the effects of particle volume fraction, thickness of the iron oxide cap, and assembly time on the final assembly behavior are studied. Cap thickness is shown not to influence the assembly behavior, while particle volume fraction and assembly time affect the chain growth rate and the chain length, but not the overall assembly behavior. The samples are characterized by optical, scanning electron, and atomic force microscopies.
authors.affiliation: Department of Chemical Engineering, City College of New York, City University of New York, 140th St. and Convent Ave., New York, New York 10031, USA.
authors.forename: Bin
authors.initials: B
authors.lastname: Ren
authors.forename: Aleksey
authors.initials: A
authors.lastname: Ruditskiy
authors.forename: Jung Hun Kevin
authors.initials: JH
authors.lastname: Song
authors.forename: Ilona
authors.initials: I
authors.lastname: Kretzschmar