Novel high intrinsic permittivity in new perovskite ceramic GdCa2Cu3Oδ

Abstract

In the present work, the GdCa2Cu3Oδ (GdCCO) compound was prepared using the conventional solid-state reaction tool, and their crystal structures and dielectric properties were systematically studied. X-ray diffraction analysis and Rietveld refinement results confirmed that GdCCO perovskite crystallizes in the tetragonal structure with the P4/mmm space group. Thermogravimetry (TG) and Differential Scanning Calorimetry (DSC) analysis confirm the decomposition of CaCO3 into calcium oxide (CaO) solid and carbon dioxide (CO2) gas at 800 °C. The composition of the grains was qualitatively examined using the EDX system attached to scanning electron microscopy (SEM). The XPS analysis was performed to investigate the oxidation state of the GdCCO perovskite elements. The frequency and temperature dependences of the complex impedance spectra and the dielectric responses of the compound GdCCO synthesized have been investigated. We first observed two semicircles conforming to grain and grain boundary responses in the impedance plots. Further, than the ambient temperature, the magnitude of the permittivity from the grain boundary (εr′ = 104 and C = 10−11 F) remains constant over most of the frequency range but decreases rapidly in the MHz frequency region. The temperature dependences of the dielectric responses show the excellent temperature stability of ε′ (Δε′=±15%), a wide temperature side (-30 – 125 °C), and higher performance of characteristics (giant ε′ 104 and low dielectric loss). These excellent performances confirmed that the prepared ceramic reveals a potential application for high-temperature Y5R and Y6R capacitors.