One-step synthesis of Pb–Sb nanostructured alloy particles: Effect of processing parameters

The present investigation reports the successful synthesis of nanostructured Pb–Sb alloys via solvothermal route for the first time. Two-phase alloy nanoparticles have been prepared by proper control of the processing parameters for Pb-17.5 atom % Sb composition. The reaction parameters; time, temperature, concentrations of the reducing agent (NaBH₄, sodium borohydrate) and most importantly, the presence of capping agent (PVP, polyvinyl pyrrolidone) have been found to play a crucial role in the formation of two-phase alloy nanoparticles. The detailed analysis of the X-ray diffraction (XRD) patterns reveals that the FCC (Pb) and rhombohedral (Sb) phases are present in each nanoparticle. The extensive transmission electron microscopy (TEM) study, including high angle annular dark field (HAADF) imaging and energy dispersive spectroscopic (EDS) analysis, carried out with annular dark field and EDS detectors respectively, attached with TITAN suggest that each nanoparticle consists of (Pb) and (Sb), with cap on body morphology. A few of them exhibit typical lamellar morphology. A possible reaction mechanism based on the experimental results has been proposed. - Highlights: • Multiphase Pb–Sb alloy nanoparticles have been synthesized by solvothermal route. • The processing conditions were optimized at temperature = 140 °C, time ≥12 h, MR of precursor/NaBH₄ as 1:3 and absence of capping agent. • Capping agent has been observed to retard the formation of two phase alloy nanoparticles. • The synthesized samples were characterized with XRD and TEM techniques. • Two specific morphologies of alloy nanoparticles are observed; cap on body and lamellar.