title: Ultrasonic alloying of preformed gold and silver nanoparticles.
abstract: Alloyed gold/silver nanoparticles with a core/shell structure are produced from preformed gold and silver nanoparticles during ultrasonic treatment at different intensities in water and in the presence of surface-active species. Preformed gold nanoparticles with an average diameter of 15 + or - 5 nm are prepared by the citrate reduction of chloroauric acid in water, and silver nanoparticles (38 + or - 7 nm) are formed after reduction of silver nitrate by sodium borohydride. Bare binary gold/silver nanoparticles with a core/shell structure are formed in aqueous solution after 1 h of sonication at high ultrasonic intensity. Cationic-surfactant-coated preformed gold and silver nanoparticles become gold/silver-alloy nanoparticles after 3 h of sonication in water at 55 W cm(-2), whereas only fusion of isolated gold and silver nanoparticles is observed after ultrasonic treatment in the presence of an anionic surfactant. As the X-ray diffraction profile of alloyed gold/silver nanoparticles reveals split, shifted, and disappeared peaks, the face-centered-cubic crystalline structure of the binary nanoparticles is defect-enriched by temperatures that can be as high as several thousand Kelvin inside the cavitation bubbles during ultrasonic treatment.
authors.affiliation: Department of Interfaces, Max-Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Golm/Potsdam, Germany. darya.radziuk@mpikg.mpg.de
authors.forename: Darya V
authors.initials: DV
authors.lastname: Radziuk
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Dmitry
authors.initials: D
authors.lastname: Shchukin
authors.forename: Helmuth
authors.initials: H
authors.lastname: Möhwald
mesh_terms: D000327:Adsorption; D000497:Alloys / Q000737:chemistry*; D000588:Amines / Q000737:chemistry; D003102:Colloids; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D012834:Silver / Q000737:chemistry*; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013010:Sonication; D013056:Spectrophotometry, Ultraviolet; D014465:Ultrasonics; D014867:Water / Q000737:chemistry; D014961:X-Ray Diffraction
chemical_list: D000497:Alloys; D000588:Amines; D003102:Colloids; D014867:Water; D012967:Sodium Dodecyl Sulfate; D012834:Silver; D006046:Gold; C003935:dodecylamine