Title: Processing, structural and electric properties of CaCu₃Ti₄O₁₂ (CCTO) doped with GeO₂

Authors: F. Amaral, C.C. Silva, M.A. Valente, L.C. Costa

Addresses: I3N and Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal; School of Technology and Management of Oliveira do Hospital, 3400-124 Oliveira do Hospital, Portugal. ' I3N and Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal; Telecommunications and Materials Science and Engineering Laboratory (LOCEM), Physics Department, Federal University of Ceara, Fortaleza, Brazil. ' I3N and Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal. ' I3N and Physics Department, University of Aveiro, 3810-193 Aveiro, Portugal

Abstract: The CaCu₃Ti₄O₁₂ (CCTO) is a material with a giant dielectric constant at room temperature and good temperature stability over a wide temperature and frequency ranges. The preparation method and doping has a great influence on the microstructure and dielectric properties of this material. In this work, the samples were prepared starting from CuO, TiO₂, CaCO₃ and GeO₂ in appropriate amounts to obtain CaCu₃Ti_4−xGe_xO₁₂ with x = 0 and x = 0.1. Three processing methods were used: solid state technique, high energy ball milling and microwave processing in a domestic microwave oven. The samples were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and dielectric measurements. The presence of nanocrystals was confirmed by XRD. The composition of the grains and grain boundaries has been determined by SEM with energy dispersive X-ray spectrometry mapping. AC impedance spectroscopy measurements in the 10²-10⁷ Hz frequency range, at room temperature, have been performed. The obtained results are discussed and correlated with the preparation method.

Keywords: giant dielectric constant; dielectric relaxation; perovskite structure; ceramics; nanocrystals; nanomaterials; nanotechnology; CaCu3Ti4O12; CCTO.

DOI: 10.1504/IJNM.2010.029920

International Journal of Nanomanufacturing, 2010 Vol.5 No.1/2, pp.25 - 37

Published online: 03 Dec 2009 *

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