Synthesis of nanocrystalline giant dielectric constant Gd2CuO4 ceramic by Pechini process

Phase pure (T´-type, sp. gp. I4/mmm), nanocrystalline Gd₂CuO₄ powders were synthesized by a wet chemical citrate gel complexation process known as “Pechini process”. The T´-type phase was realized at much lower (~ 1073 K) temperature than those reported for conventional ceramic powder mixing and solid state reaction process (~ 1223 K). The average particle size of the solid state reacted particles from HR-TEM was found to be ~ 50 nm. The dielectric studies on the Gd₂CuO₄ pellets revealed extremely high values of ε´_r (= 10⁴) over the measure frequencies (1 ≤ f ≤ 1 MHz) and temperature (173 K ≤ T ≤ 423 K) ranges. Being non-ferroelectric, we propose such high values of ε´_r arise due to an Internal barrier layer capacitance effect, formed by insulating grain boundaries and semiconducting grains in the ceramics.