Exceptionally High Dielectric Constant in Ceramic Pr₂CuO₄

Abstract

The pristine layered cuprate Pr2CuO4 samples of >95% density were fabricated as thin disks. The samples, analyzed by X‐ray diffraction and Scanning electron microscopy, showed clean T′‐type phase with Rietveld refined lattice parameters a = b = 3.95805(±5) Å and c = 12.2262(±5) Å. The measured dielectric properties of the Pr2CuO4 ceramics, in the temperature range −100°C–150°C and frequencies (ν) 0.1 Hz–1 MHz, showed extremely high εr′ > 104 (above −30°C), and dissipation (tan δ = εr′′/εr′) between 0.1 and 5 (for 500 Hz ≤ ν ≤ 1 MHz, and −100 ≤ T ≤ 150°C). The ac conductivity of Pr2CuO4 ceramics ranged between 10−6 and 10−3 Scm−1 for the measured frequencies and temperatures, and showed frequency‐dependent double power law behavior akin to a modified Jonscher's power law.

Impedance and AC conductivity study of nano crystalline, fine grained multiferroic bismuth ferrite (BiFeO3), synthesized by microwave sintering

“…However, there have a lot of reports on the applicability of internal barrier layer capacitance (IBLC) effect in few of the oxide ceramics which have shown exceptionally high ε r ′ albeit showing high loss. 17,18,21,34,[49][50][51][52][53] This IBLC effect arises predominantly due to the heterogeneity in the electrical microstructure of the ceramics. Impedance spectroscopy is a useful tool to study the electrical heterogeneity of the sample, which can be done by deciphering the contribution of the grain and grain boundaries.…”

Giant dielectric response and magnetoelectric behavior of 95BiFeO3–5BaTiO3 (95BFO–5BT) ceramics

“…The values of C g were found between 10 -10 and 10 -11 F, while the C gb values were found to vary between 10 -8 and 10 -9 F. The value of R gb was found to be (C10 4 X) which is only 1-2 orders higher than the grain resistance, R g (B10 3 X). Usually the network of insulating grain boundaries and semiconducting grains could give rise to the internal barrier layer capacitance (IBLC) effect, as observed in many high dielectric and high loss oxide electro-ceramics [24,29,30]. However, in this sample the difference in grain and grain boundary resistance is not that much.…”

“…and oxygen vacancies (Vo 2? ) due to the volatilization of Bi 2 O 3 [29]. The reaction in the Kroger-Vink notation can be written as…”