Dielectric properties of Nb-doped CaCu3Ti4O12 electroceramics measured at high frequencies

Abstract

In this work, Nb dopant was introduced into CaCu₃Ti₄O₁₂ (CCTO) electroceramic in order to improve the dielectric properties. The CCTO electroceramic was prepared using the solid state reaction method. An X-ray diffractometer (XRD) analysis proved the formation of a single CCTO phase after sintering at 1040 °C for 10 h. Abnormal grain growth was observed in undoped CCTO and 1 mol% Nb-doped CCTO. Normal grain growth was produced at Nb dopant levels higher than 3 mol%. Dielectric properties were measured at a frequency range of 1 MHz to 1 GHz. It was found that CCTO doped with 1 mol% Nb gave the highest dielectric constant of 18,000 at 1 MHz. Meanwhile, the lowest dielectric loss (0.31) at 1 MHz was given by CCTO doped with 10 mol% Nb. The dielectric constant between 10 MHz and 1 GHz was almost stable with values at around 500.

Keywords

• Ceramics;
• Solid state reaction;
• Sintering;
• Dielectric response;
• Scanning electron microscopy;
• X-ray diffraction

Journal of Alloys and Compounds

Volume 493, Issues 1–2, 18 March 2010, Pages 486–492