Effect of Europium Addition on the Microstructure and Dielectric Properties of CCTO Ceramic Prepared Using Conventional and Microwave Sintering

Abstract

In this work, Eu₂O₃-doped (CaCu₃Ti₄O₁₂)_x of low dielectric loss have been fabricated using both conventional (CS) and microwave sintering (MWS), where x = Eu₂O₃ = 0.1, 0.2, and 0.3, respectively. According to X-ray diffraction (XRD) and scanning electron microscope (SEM) reports, increasing the concentration of Eu³⁺ in the CCTO lattice causes the grain size of the MWS samples to increase and vice versa for CS. The X-ray photoelectron spectroscopy (XPS) delineated the binding energies and charge states of the Cu²⁺/Cu⁺ and Ti⁴⁺/Ti³⁺ transition ions. Energy dispersive spectroscopy (EDS) analysis revealed no Cu-rich phase along the grain boundaries that directly impacts the dielectric properties. The dielectric characteristics, which include dielectric constant (ε) and the loss (tan δ), were examined using broadband dielectric spectrometer (BDS) from 10 to 10⁷ Hz at ambient temperature. The dielectric constant was >10⁴ and >10² for CS and MWS samples at x > 0.1, respectively, with the low loss being constant even at high frequencies due to the effective suppression of tan δ by Eu³⁺. This ceramic of low dielectric loss has potential for commercial applications at comparatively high frequencies.

Keywords: CCTO; conventional sintering; dielectric loss; europium; microstructure; microwave sintering.