J. Mater. Sci. Technol. ›› 2020, Vol. 41: 12-20.DOI: 10.1016/j.jmst.2019.08.055

• Research Article • Previous Articles     Next Articles

Improvement in varistor properties of CaCu3Ti4O12 ceramics by chromium addition

Edson Cezar Grzebieluckaa*(), João Frederico Haas Leandro Monteiroa, Eder Carlos Ferreira de Souzaa, Christiane Philippini Ferreira Borgesa, André Vitor Chaves de Andradeb, Eloísa Cordoncilloc, Héctor Beltrán-Mirc, Sandra Regina Masetto Antunesa   

  1. aPrograma Pós-Graduação em Química Aplicada, Universidade Estadual de Ponta Grossa, Av. Gen. Carlos Cavalcanti 4748, 84.030-000, Ponta Grossa, Paraná, Brazil
    bPrograma de Pós-Graduação em Ciências/Física, Universidade Estadual de Ponta Grossa, Av. Gen. Carlos Cavalcanti 4748, 84.030-000, Ponta Grossa, Paraná, Brazil
    cDpto. de Química Inorgánica y Orgánica, Universitat Jaume I, Av. de Vicent Sos Baynat, s/n, 12071, Castellón de la Plana, Spain
  • Received:2019-07-02 Revised:2019-08-07 Accepted:2019-08-20 Published:2020-03-15 Online:2020-04-10
  • Contact: Cezar Grzebielucka Edson

Abstract:

The effect of chromium addition on the structure and electrical properties of CaCu3Ti4O12 is studied. Compositions based on the formula CaCu3Ti4-xCrxO12-δ (x = 0, 0.025, 0.050 and 0.075 mol%) are prepared by solid-state reaction. Pellets sintered at 1070 °C for 12 h are characterised by X-ray diffraction, scanning electron microscopy/energy dispersive spectroscopy and impedance spectroscopy. Current density-electric field, dielectric loss and permittivity measurements are also carried out. Rietveld refinement showed the substitution of Cr(III) on the Ti(IV) site, with the maximum substitution for x = 0.025 mol%. The generation of electrical defects in the grain boundary region by chromium doping is responsible for increasing the electric breakdown field strength and nonlinearity coefficient at room temperature from 1723 V/cm and 5.29 for x = 0 mol% to 3431 V/cm and 8.16 for x = 0.025 mol%. This composition shows the greatest improvement in ceramic varistor parameters.

Key words: CCTO, Structural analysis, Impedance, Varistor, Rietveld