Exceptionally High Dielectric Constant in Ceramic Pr 2 CuO 4

The pristine layered cuprate Pr 2 CuO 4 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 Pr 2 CuO 4 ceramics, in the temperature range −100°C–150°C and frequencies (ν) 0.1 Hz–1 MHz, showed extremely high ε r ′ > 10 4 (above −30°C), and dissipation (tan δ = ε r ′′/ε r ′) between 0.1 and 5 (for 500 Hz ≤ ν ≤ 1 MHz, and −100 ≤  T  ≤ 150°C). The ac conductivity of Pr 2 CuO 4 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.