Correlation of structural, microstructure and dielectric properties of substituted and un-substituted CaCu3Ti4-xAxO12 ceramics

Abstract

CaCu3Ti4-xAxO12 (CCTAO) ceramics, where A is one of the following: no ion, Nd3+, Gd3+, Sb3+ or Sn4+ were synthesized by the solid-state reaction method. The effects of ion substitution into CCTAO ceramics on the structure, microstructure and dielectric properties were studied. The structure of the CCTAO ceramics was characterized by X-ray diffraction with the patterns fit by the Rietveld refinement technique using the FullProf program. The results indicated that all the samples were mono-phased and had a cubic structure. Gd3+, Nd3+, Sb3+ and Sn4+ ions strongly inhibited grain growth in CCTAO ceramics. The densification increased and porosity decreased with the addition of Gd3+, Nd3+ and Sb3+ ions. The dielectric loss of CCTAO ceramics substituted with a very small amount of Sb3+ greatly reduced, while maintaining a high dielectric constant. The dielectric loss of CCTAO ceramics substituted with a very small amount of Sb3+ greatly reduced, while maintaining a high dielectric constant. The substitution of Gd3+ increased the dielectric constant and dielectric loss. The substitution of Nd3+ and Sn4+ caused a drop of the dielectric constant at low temperatures and increased the dielectric constant at high temperatures by >90 °C for Nd3+ and >130 °C for Sn4+.