Influence of temperature on silver nanoparticle size prepared by sputtering into PVP-glycerol system

Nanoparticles (NPs) are revolutionizing many areas of science and technology, often delivering unprecedented improvements to properties of the conventional materials. Hence, the development of innovative methods capable of producing uniform, sufficiently clean and stable NPs is desirable. In this regard the cathode sputtering into systems with low vapor pressure seems to be a promising technique. It combines benefits resulting from easily acquirable monodisperse NP solutions with the possibility to control their size just by varying the temperature through the deposition process. This work focuses on temperature control of the polyvinylpyrrolidone-glycerol system (PVP-glyc) during cathode sputtering of silver. We chose the PVP-glyc solution owing to significant temperature dependence of its viscosity, which was varied in temperature range 5-40 °C. Silver NPs were investigated by ultraviolet-visible spectrometry, transmission electron microscopy and dynamic light scattering. In the temperature range from 5 to 20 °C we observed a remarkable increase in NPs average size from 12.8 nm (5 °C) to 21.2 nm (20 °C). However, when deposition temperatures exceeded 25 °C, we registered a significant vaporization of glycerol, resulting in final average size of NPs of about 8 nm. Our results indicate that the PVP-glyc is suitable system for temperature-controlled deposition of metal NPs, enabling tuning of their size.