Structural characterization of dense reduced BaTiO and BaLaTiO nanoceramics showing colossal dielectric values

Zarel Valdez Nava (1) , C. Tenailleau (1) , S. Guillemet-Fritsch (1) , N El Horr (1) , Thierry Lebey (2) , P. Dufour (1) , B. Durand (1) , J-Y. Chane-Ching (1)

1 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux
2 LAPLACE-MDCE - Matériaux Diélectriques dans la Conversion d’Energie

BaTiO and BaLaTiO nanoceramics showing colossal permittivity values have been characterized. While starting powders are of cubic symmetry, X-Ray and Neutron Diffraction techniques, and Raman Spectroscopy measurements show that the one-step processed ceramics obtained by Spark Plasma Sintering (SPS) contain cubic and tetragonal phases. The rather large oxygen deficiency determined in such ceramics by Electron Micro Probe Analysis and Electron Energy Loss Spectroscopy analyzes is explained by the presence of Ti, as evidenced by X-ray Photoelectron Spectroscopy measurements. Transmission Electron Microscopy and High Resolution Transmission Electron Microscopy show that these ceramics contain 50-300nm grains which have single-domains, while grain boundaries are of the nanometer scale. Colossal permittivity values measured in our dense nanoceramics are explained by a charge hopping mechanism and interfacial polarization of a large number of polarons generated after sample reduction in SPS apparatus.

Mots clés: A. Ceramics; A. Nanostructures; C. Raman spectroscopy; C. X-ray diffraction; D. Dielectric properties

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Zarel Valdez Nava, C. Tenailleau, S. Guillemet-Fritsch, N El Horr, Thierry Lebey, et al.. Structural characterization of dense reduced BaTiO and BaLaTiO nanoceramics showing colossal dielectric values. Journal of Physics and Chemistry of Solids, 2010, 72 (1), pp.17. ⟨10.1016/j.jpcs.2010.10.016⟩. ⟨hal-00700806⟩