Interactions of floating-wire-assisted atmospheric-pressure H$_{\mathrm{2}}$/Ar plasma with SnO$_{\mathrm{2}}$ film on glass substrate forming spherical Sn particles*

Tin (Sn) metal has been extracted from ores for a long time and is a highly demanded material for industrial applications To extract Sn metal from SnO$_{\mathrm{2}}$, various reduction processes required high-treatment temperatures and reducing agents such as CH$_{\mathrm{4}}$ that produces CO$_{\mathrm{2}}$ emission In this study, the floating-wire-assisted atmospheric-pressure plasma using a mixture of 0.05{\%} H$_{\mathrm{2}}$/Ar gas can reduce SnO$_{\mathrm{2}}$ film on glass substrate to form Sn spheres without using any additional heater. The H$_{\mathrm{2}}$/Ar plasma with a high electron density of 10$^{\mathrm{14}}$ cm$^{\mathrm{-3}}$, a hydrogen atom density of 10$^{\mathrm{14}}$ cm$^{\mathrm{-3}}$, and a rotational temperature of 940 K was obtained at a remote distance of 150 mm. A model for the formation of spherical Sn particles from SnO$_{\mathrm{2}}$ film on glass substrate in H$_{\mathrm{2}}$/Ar plasma is presented here. The treatment time and substrate temperature affect the expansion rate of the reduction area and the growth of Sn spheres. The results present a green method to synthesize Sn particles from SnO$_{\mathrm{2}}$ in atmospheric-pressure plasma for various applications.