Synthesis and electrical properties of silver nanoplates for electronic applications

In this paper, silver nanoplates of 100 to 500 nm size were synthesized by reduction of silver nitrate with N,Ndimethylformamide, using poly(vinylpyrolidone) as a surfactant and ferric chloride as a controlling agent, at 120 to 160 °C for 5 to 24 hours. The influence of the concentration of ferric chloride, the reaction temperature and reaction time on the morphology of the product has been investigated by transmission electron microscopy, scanning electron microscopy and UV-Vis spectroscopy. The results indicated that the products obtained at the low reaction temperature and short reaction time in the presence of FeCl₃ in the reaction solution were in the form of silver nanoplates, whose morphology was mainly triangular and hexagonal. In addition, the size and thickness of the nanoplates increased with increasing of the FeCl₃ concentration. At a high reaction temperature and long reaction time, the truncated triangle and hexagonal nanoplates were mainly produced. Furthermore, the sintering behavior of nanoplates was studied and the results showed that sintering of the silver nanoplates started at 180 °C, and a typical sintering behavior was observed at higher temperatures. The incorporation of the silver nanoplates into the polymer matrix with micro-sized silver flakes led to an increase in the matrix resistivity in almost all cases, especially at high fractions and low curing temperatures. The curing temperature had an influence on the resistivity of the conductive adhesives filled with micro-sized silver flakes and silver nanoplates due to sintering of the silver nanoplates.