Observations on the melting of Au nanoparticle deposits and alloying with Ni via in situ synchrotron radiation x-ray diffraction

Through monitoring the evolution of the x-ray diffraction peaks, the transient low temperature melting of Au nanoparticles and following alloying with the substrate were demonstrated via in situ synchrotron radiation x-ray diffraction. Upon heating, the broad diffraction peak of nanosized Au particles with the average diameter of 2.5 nm was suppressed at about 200 °C and soon became sharp due to melting and subsequent solidification. If the test was conducted on a Ni film, an unstable intermetallic compound Au₃ Ni appeared with crystallized Au, which resulted from the reaction between the supercooled liquid of Au and Ni. However, it decomposed at 275 °C and above.