Nanocomposites and Nanomaterials

Synthesis, optical and morphological studies of ZnO powders, and thin films fabrication by wet chemical methods
Szczesny R.1, Derkowska-Zielinska B.2, Skowronski L.3, Wang H.4, 
Boudebs G.4, Viter R.5, Scigala A.1, Szlyk E.1
1 Faculty of Chemistry, Nicolaus Copernicus University in Torun, Gagarina 7, 87-100 Torun, Poland. 
E-mail: roszcz@umk.pl
2 Institute of Physics, Faculty of Physics, Astronomy and Informatics, Nicolaus Copernicus University in Torun, Grudziadzka 5, 87-100 Torun, Poland.
E-mail: beata@fizyka.umk.pl
3 Institute of Mathematics and Physics, UTP University of Science and Technology, S. Kaliskiego 7, 85-796 Bydgoszcz, Poland.
4 Laboratoire de Photonique d'Angers, LPHIA, EA 4464, SFR MATRIX, UNIV Angers, 2 Boulevard Lavoisier, 49045 Angers France
5 Institute of Atomic Physics and Spectroscopy, University of Latvia, 19 Raina Blvd., Riga, LV 1586, Latvia.

Zinc oxide is a colorless, wide band gap semiconductor. Nanostructures of ZnO have been investigated for optoelectronics, catalysis and sensing. [1,2]. Nanosized ZnO particles are biocompatible, cheap, nontoxic, environmentally friendly and shows antimicrobial activities. The nanocomposites of ZnO in the polymeric matrix had the potential for being applied in the packaging and preservation of food [3]. It is known that the oxide layers can be obtained by physical e.g. sputtering processes, pulsed laser deposition technique or by chemical methods such as, microemulsion, hydrothermal, sol-gel and precipitation followed by the deposition of nanoparticles suspensions using wet coating methods. The use of dip- or spin-coating offers the opportunity for facile fabrication of thin films containing uniformly dispersed nanoparticles onto the substrates even for large areas, and allows to produce a wide variety of composite materials in mild conditions.
In this work, zinc hydroxy carbonate precursors were utilized to prepare ZnO NPs, and films on silicon or glass substrate. Effect of calcination conditions of precursor on the morphology of ZnO particles was studied. Morphological evaluation by TEM and SEM measurements indicated that the particles are ball-shaped structures composed of plates with a thickness of 20-40 nm. Moreover, powders were characterized by IR, XRD, PL, UV-Vis and TG. The nonlinear optical properties were experimentally studied by using Z-scan technique.
The layers of ZnO were obtained from ethanol or water suspension, including addition of polymers such as polyvinylpyrrolidone (PVP) or starch. Surface structure and morphology of the resulting films were studied by SEM and AFM microscopy, and layers with uniformly distributed ZnO plates resulting from the erosion of primary micro-particles were observed. The fabricated layers were also measured using spectroscopic ellipsometry to calculate dielectric function and thickness.

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2.	Kołodziejczak-Radzimska A., Jesionowski T. Zinc Oxide-From Synthesis to Application: A Review // Materials-2014.-7.-P. 2833-2881.
3.	Espitia P.J.P., Soares N.F.F., Coimbra J.S.R., Andrade N.J., Cruz R.S., Medeiros E.A.A. Zinc Oxide Nanoparticles: Synthesis, Antimicrobial Activity and Food Packaging Applications // Food Bioprocess Technology-2012.-5.-P. 1447–1464.