Development of advanced CaCu3Ti4O12 ceramics in the form of powders, bulks, and nanostructured films: an integrated studied of its multifunctional properties

Abstract

Ceramics based on the CaCu3Ti4O12 system have been receiving a great deal of attention due to its multifunctional properties and its potential application in lasers, LEDs, FEDs, photocatalysts, supercapacitors, varistors, gas sensors, resistive memories, etc. The objective of this project is to study the effect of the additions of X% of W6+ to the CaCu3Ti4O12 (with X= 0.00, 0.25, 0.50, 0.75, 1.00) in the form of powders and bulks prepared by solid state reaction method, and nanostructured films fabricated by the RF-sputtering method. The powders will be characterized regarding its (micro)structural and optical properties. Structures will be analyzed on the long, medium and short range using X-Ray diffratometry (XRD), XANES/EXAFS, Photoluminescent response (PL), Raman and Ultraviolet visible (UV-Vis). On the CCTO ceramics with the W6+ addition conformed as bulks, a comparative study will be performed between conventional sintering and electric field-assisted flash sintering, and its influence on (micro)structure and, dielectric and non-ohmic properties. The samples will be characterized using the Rietveld refinement technique for determining its crystalline structure and the phases present, coupled with FEG/SEM and TEM/HRTEM techniques. Impedance spectroscopy (IE) and tension-current measurements, Atomic Force Microscopy (AFM) and Electrostatic Force Microscopy (EFM), will be used in order to study the active barriers at the grain boundaries, related to the materials' dielectric and varistor responses. Nanostructured dense and porous films will be deposited on appropriate substrates using the RF-sputtering technique. On the dense films, the dielectric and varistor responses will be studied, and on the porous films, the sensor response to CO will be subject to study. In fact there is no integrated studies in the literature regarding the multifunctional properties of CCTO ceramics in the form of powders, bulks, and films, making this an innovative project from a cientific and technologic standpoint. (AU)