Effects of Zr doping on the microstructures and dielectric properties of CaCu₃Ti₄O₁₂ ceramics

Zr-doped CaCu₃Ti_3.95Zr_0.05O₁₂ (CCTZO) ceramics were prepared by sol-gel method, and pure-phased structures were observed by the X-ray diffraction. The microstructures and dielectric properties of CaCu₃Ti₄O₁₂ (CCTO) and CCTZO ceramics were investigated. The CCTZO ceramics possessed a fine-grained microstructure with grain sizes of about 3-5 μm, and the grain size uniformity of CCTZO ceramics were enhanced via doping Zr in CCTO ceramics. Meanwhile, CCTZO ceramics exhibited a broadband stability of the dielectric constant and a lower dielectric loss at high frequency ranges. The dielectric relaxation mechanisms of CCTO and CCTZO ceramics were analyzed using the mixed-valent structures. The impedance analysis suggested CCTO and CCTZO ceramics consisted of semiconducting grains and insulating grain boundaries.