A Bicontinuous Microemulsion Route to Zinc Oxide Powder

Abstract

An ultrafine zinc oxide powder of 0.15/μm in particle size has been synthesised via a microemulsion processing route, which involves preparing an inverse water-in-oil system consisting of 18.0 wt% 0.5 M Zn(NO3)2 solution as the aqueous phase, 57.4 wt% petroleum spirit (boiling point: 100-120°C) as the oil phase, and 24.6 wt% poly(oxyethylene)5 nonyl phenol ether (NP5) as the nonionic surfactant. Electrical conductivity measurement indicated that the optical transparent system exhibited a bicontinuous nanostructure. Nanosized precursor particles of zinc hydroxide were formed when an appropriate amount of 1.0 M ammonia solution was added dropwise into the bicontinuous microemulsion system. Subsequent calcination of the hydroxide precursor at 470°C for 3 h resulted in the formation of an ultrafine zinc oxide powder, which has been characterised using particle size analyser, BET specific surface area analyser, X-ray diffraction (XRD), and scanning electron microscope (SEM). © 1998 Elsevier Science Limited and Techna S.r.l.