However, the price of gold is

high, while silver tracks are plagued by electrochemical migration. Strategies such as alloying and core-shell structure have been proposed to achieve better performance. Nanoalloys of gold and silver metals, which have attracted much attention due to high catalytic activities and unique Momelotinib cost optical properties [10–13], exhibit essentially identical lattice constants and are completely miscible [14], presenting new opportunities for the development of interconnect materials [15–17]. With respect to ligand-protected NPs, the protect shell must be thermally or chemically eliminited, and the NPs need to join together to form continuous conductive networks in order to generate electrical conductance [18]. Coalescence of gold nanoparticles has been studied by means of simulation, surface plasmon resonance absorption,

and thermogravimetric analysis [18–21]. Recently, synchrotron X-ray radiations, powerful probing sources to study the structural, physical, and chemical properties of nano-materials [22], were applied to study the morphological and phase transitions of NP deposits [23, MK-4827 24]. Using synchrotron radiation X-ray diffraction (SR-XRD) and small-angle X-ray scattering (SAXS), Ingham et al. [24] proposed the mechanisms of coalescence; in sequence, they are desorption or melting of the capping ligands, aggregation of nanocrystals, necking of particles, and subsequent grain growth. However, there is still a lack of insight regarding the alloying effect on the coalescence of NPs. In

this report, a real-time and systematic study into the coalescence of binary gold-silver alloy NPs was performed. The phase evolution upon heating of thiol-protected NPs of gold, silver, and their alloys with various Au/Ag ratios (3:1, 1:1, and 1:3) was monitored by synchrotron radiation XRD. The interactions between ligands and surface atoms of alloy NPs as well as their influence on the coalescence and related properties these were investigated. Methods The preparation of the octanethiolate-stabilized gold-silver alloy nanoparticles followed a modified BIBW2992 purchase two-phase protocol proposed by Murray [25], which has been described in a previous work [26]. The nanoparticles were synthesized with varying initial Au/Ag molar ratios (0:1, 0.25:0.75, 0.5:0.5, 0.75:0.25, and 1:0) and designated as Au, Au3Ag, AuAg, AuAg3, and Ag, respectively. The UV-visible spectra of the nanoparticle solutions were measured by a spectrophotometer (Varian Cary 100 UV-Visible spectrometer, Palo Alto, CA, USA) with a 10-mm quartz cell. A transmission electron microscope (FEI-TEM, Philips Technai G2, Amsterdam, Netherlands) with an accelerating voltage of 200 kV was used to observe the morphology of the NPs and the particle size was measured using Scion Image 4.0.2 image analysis software. NPs were suspended in tolune solvent with the proportion of 20% by weight.