Effect of La-doping on the properties of CaCu 3Ti 4O 12 dielectric ceramics

Abstract

Nano-size Ca 1− χ La 2 χ/3 Cu 3Ti 4O 12 ( χ = 0.00, 0.05, 0.10, 0.15 and 0.20) precursor powders were prepared via the sol–gel method and the citrate auto-ignition route and then processed into micro-crystal Ca 1− χ La 2 χ/3 Cu 3Ti 4O 12 ceramics under heat treatment. Characterization of the as-obtained ceramics with XRD and SEM showed an average grain sizes of ∼1–2 μm, indicating La 3+ amount to have little impact on grain size. The room-temperature dielectric constant of the Ca 1− χ La 2 χ/3 Cu 3Ti 4O 12 ceramics sintered at 1000 °C was of the order of 10 3–10 4 despite the variation of χ values. Compared with CaCu 3Ti 4O 12, La 3+-doped CaCu 3Ti 4O 12 showed a flatter dielectric constant curve related to frequency. It was found that the loss tangent of the Ca 1− χ La 2 χ/3 Cu 3Ti 4O 12 ceramics was less than 0.20 in ∼600–10 5 Hz region, which rapidly decreased to a minimum value of 0.03 by La 3+doping with χ = 0.05. Our measurement of the ceramics conductivities ( σ) also indicated that the appropriate introduction of La 3+ into CaCu 3Ti 4O 12 would distinctly result in its dielectric properties.