ZnO nanocrystallites obtained by oxidation of zinc arachidate - arachidic acid composite multilayers

Abstract

ZnO nanocrystallites were prepared by the oxidation of Zinc Arachidate-Arachidic Acid (ZnA-AA) composite multilayers grown on quartz and freshly cleaved mica substrates. Control of zinc content in the multilayers was achieved by the manipulation of the subphase pH and the variation in the number of monolayers transferred. FTIR studies of multilayers show a gradual decrease in ZnA content as the subphase pH is reduced. X-ray reflection studies show the presence of a single layered structure in all the as deposited multilayers transferred at different subphase pH. These observations suggest molecular level mixing of ZnA and arachidic acid molecules. The precursor multilayers were oxidized in the temperature range of 100-700 degrees C. The formation of ZnO is confirmed by UV-Visible spectroscopy. Atomic force micrographs show that the oxidation treatment resulted in either large agglomerates of ZnO nanocrystallites or isolated nanocrystallites, depending on the zinc content of the precursor multilayers. Typically, 7 monolayers ZnA-AA transferred at subphase pH of 5.0 on mica and oxidized at 700 degrees C resulted in uniformly distributed, isolated and nearly mono-dispersed nanocrystallites of size 11 3 run. (c) 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.