Microwave synthesis of ZrO 2 and Yttria stabilized ZrO 2 particles from aqueous precursor solutions
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Microwave synthesis of ZrO2 and Yttria stabilized ZrO2 particles from aqueous precursor solutions Kenny Vernieuwe1, Petra Lommens1, Freya Van den Broeck2, José C. Martins2, Isabel Van Driessche1, Klaartje De Buysser1 1 SCRiPTS, Department of Inorganic and Physical Chemistry, Ghent University, 218-S3 Krijgslaan, Ghent, B-9000, Belgium 2 NMR and structure analysis, Department of Organic Chemistry, Ghent University, 218-S4 Krijgslaan, Ghent, B-9000, Belgium ABSTRACT Zirconia and Yttrium stabilized zirconia are well-known ceramic materials. Scaling down the dimension of these ceramics can result in a faster sintering process at lower temperatures. Microwave synthesis of nano-structured particles is a very attractive synthesis route because of the short synthesis time and low reaction temperature. This allows a fast screening of the influence of different parameters such as time, temperature and pressure on the final size and crystal phase of the particles. In this study Zr and Zr/Y aqueous precursors are mixed with a variety of complexing agents or surfactants in different ratios. The reason is twofold: (1) we aim for a stable precursor solution which is established by lowering the free ion concentration and (2) we want to see the influence of the complexing agents on the growth of the particles and the formation of crystalline phases. Particle sizes of these particle vary from 40 -200 nm. The crystallinity is confirmed by X-ray diffraction. The stabilization of these particles and possible exchange of the ligands is examined with NMR measurements (1D - proton combined with 2D NOESY) and is compared with TGA-DTA analysis of the isolated particles. INTRODUCTION Ceramics are by definition a combination of metallic and non-metallic elements which gain their specific properties by a high temperature treatment. The temperatures necessary for crystallization and formation of the desired phases can be very high resulting in an high energy consumption [1]. In the light of green chemistry and environmental and energy friendly processes a lot of effort has been put in the research towards novel synthesis and preparation routes that overcome this temperature barrier. Well established solid state reactions for formation of ceramic use the shake-and-bake method in order to homogenize the precursor mixture and the increase the inter-granular contacts. Solution chemistry routes avoid those intensive milling and mixing steps and ensure a homogeneity of the precursor to the atomic level [2, 3]. Off course, precipitation has to be prevented at all times to avoid non-stochiometric precursor solutions. Solution chemistry routes allow beside the formation of bulk ceramics, the deposition of ceramic thin films by dip-coating, spin-coating, spray-coating or even ink-jet printing [4-7]. In all the above mentioned systems there is still a need for a high temperature treatment for the formation of the desired crystalline phase. In this work we focus on the synthesis of ceramic nanoparticles from solution precursors. These particles should be as
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