title: Successful synthesis and thermal stability of immiscible metal Au-Rh, Au-Ir andAu-Ir-Rh nanoalloys.
abstract: We successfully prepared face-centred cubic nanoalloys in systems of Au-Ir, Au-Rh and Au-Ir-Rh, with large bulk miscibility gaps, in one-run reactions under thermal decomposition of specially synthesised single-source precursors, namely, [AuEn2][Ir(NO2)6], [AuEn2][Ir(NO2)6]х[Rh(NO2)6]1-хand [AuEn2][Rh(NO2)6]. The precursors employed contain all desired metals 'mixed' at the atomic level, thus providing significant advantages for obtaining alloys. The observations using high-resolution transmission electron microscopy show that the nanoalloy structures are composed of well-dispersed aggregates of crystalline domains with a mean size of 5 ± 3 nm. Еnergy dispersive x-ray spectroscopy and x-ray powder diffraction (XRD) measurements confirm the formation of AuIr, AuRh, AuIr0.75Rh0.25, AuIr0.50Rh0.50and AuIr0.25Rh0.75metastable solid solutions. In situ high-temperature synchrotron XRD (HTXRD) was used to study the formation mechanism of nanoalloys. The observed transformations are described by the 'conversion chemistry' mechanism characterised by the primary development of particles comprising atoms of only one type, followed by a chemical reaction resulting in the final formation of a nanoalloy. The obtained metastable nanoalloys exhibit essential thermal stability. Exposure to 180 °C for 30 h does not cause any dealloying process.
authors.affiliation: Nikolaev Institute of Inorganic Chemistry, 3, Acad. Lavrentiev Ave., Novosibirsk, 630090, Russia. Novosibirsk State University, 2, Pirogova Str., Novosibirsk. 630090, Russia.
authors.forename: Yury
authors.initials: Y
authors.lastname: Shubin
authors.forename: Pavel
authors.initials: P
authors.lastname: Plyusnin
authors.forename: Marat
authors.initials: M
authors.lastname: Sharafutdinov
authors.forename: Evgenia
authors.initials: E
authors.lastname: Makotchenko
authors.forename: Sergey
authors.initials: S
authors.lastname: Korenev