Influence of different dopant sites by lanthanum on the dielectric properties of CaCu3Ti4O12 ceramics

Abstract

The effects of La3+ doped in calcium copper titanate (CCTO) at Ca2+ site and Cu2+ site were examined. The doped compositions, La0.1Ca0.85Cu3Ti4O12 (LCCTO) ceramics and CaLa0.1Cu2.85Ti4O12 (CLCTO) ceramics were prepared by the solid-state method. The microstructure, dielectric properties, complex impedance and nonlinear I–V characteristics were studied. And it was found that La3+ doped at Ca2+ site achieved lower sintering temperatures than that doped at Cu2+ site in CCTO ceramics. The dielectric loss (tan δ) of LCCTO ceramics was about 0.05 at 40 kHz when the sample was sintered at 1080 °C. Dielectric constant (e′) of LCCTO ceramics was about 3.2 × 104 when the sample was sintered at 1100 °C, which was larger than CLCTO ceramics examined under the same process condition with sintering temperatures vary. The impedance analysis revealed that LCCTO ceramics had an influence of resistance of grain boundaries, which was stronger than that of CLCTO ceramics. Meanwhile, both LCCTO ceramics and CLCTO ceramics had a nonlinear-Ohmic property.