Evaluation of the Dispersion Stability of AZO Mesocrystals for Their Processing into Functional Thin Films Using Small Angle X-ray Scattering

Abstract

<jats:p>Within the scope of the comprehensive elucidation of the entire process chain for the production of highly functional thin films made of semiconducting aluminum-doped zinc oxide ( A Z O ) nanocrystals, this work deals with the detailed investigation of the stabilization sub-process, considering the requirements for the subsequent coating process. An innovative investigation procedure using non-invasive small angle X-ray scattering ( S A X S ) is developed, enabling an evaluation of qualitative and quantitative dispersion stability criteria of sterically stabilized A Z O nanocrystals. On the one hand, qualitative criteria for minimizing layer inhomogeneities due to sedimentation as well as aggregate formation are discussed, enabling a high particle occupancy density. On the other hand, a procedure for determining the A Z O concentration using S A X S , both in the stable phase and in the non-stabilized phase, is demonstrated to provide a quantitative evaluation of the stabilization success, having a significant impact on the final layer thickness. The obtained insights offer a versatile tool for the precise stabilization process control based on synthesis process using S A X S to meet coating specific requirements and thus a successful integration into the entire process chain for the production of functional A Z O thin films.</jats:p>

Characterization of Fractal Structures by Spray Flame Synthesis Using X-ray Scattering

“…Their small size leads to a high surface-to-volume ratio and other effects, such as high porosity, a lower melting point and high van-der-Waal forces [ 1 , 2 ]. Depending on the composition, metal oxides can show para magnetism (iron oxides) [ 3 ], photocatalytic behavior (titania) [ 4 ], high toughness and wear resistance (zirconia) [ 5 ], electrical conductivity (aluminum-doped zinc oxid) [ 6 ] or insulation properties (silica) [ 7 ]. One approach to produce metal oxide nanoparticles, is flame spray synthesis, which is generally a fast process, very flexible in terms of switching material systems and relatively easily scaled up to industrial production rates [ 8 , 9 ].…”