Dielectric properties of high-permittivity A_2/3CuTa₄O₁₂ ceramics

Abstract

Purpose

This paper aims to present the comparative study on the composition, microstructure and dielectric behavior of a group of new nonferroelectric high-permittivity A_2/3CuTa₄O₁₂ (A = Y, Nd, Sm, Gd, Dy or Bi) ceramics.

Design/methodology/approach

The materials under investigation were synthesized by solid-state reaction method and sintered at 1,120-1,230°C. Dielectric properties were investigated in the temperature range from −55 to 740°C at frequencies 10 Hz to 2 MHz. Microstructure, elemental composition and phase composition of the ceramics were examined by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) methods. DC conductivity was studied in the temperature range 20-740°C.

Findings

XRD analysis revealed peaks corresponding to Cu₂Ta₄O₁₂ along with small amounts of secondary phases based on tantalum oxides. Impedance spectroscopic data and the results of SEM and EDS studies imply the spontaneous formation of internal barrier layer capacitors in the investigated materials. Two steps can be distinguished in the dielectric permittivity versus frequency plots. The low-frequency step of 1,000-100,000 is assigned to grain boundary barrier layer effect, while the high-frequency one of 34-46 is related to intrinsic properties of grains.

Originality/value

Search for new high-permittivity capacitor materials is important for the progress in miniaturization and integration scale of electronic passive components. The paper reports on processing, microstructure, microanalysis studies and dielectric properties of a group of novel nonferroelectric materials with the perovskite structure of CaCu₃Ti₄O₁₂ and the general formula A_2/3CuTa₄O₁₂, being spontaneously formed internal barrier layer capacitors.

Citation

Szwagierczak, D. (2014), "Dielectric properties of high-permittivity A_2/3CuTa₄O₁₂ ceramics", Microelectronics International, Vol. 31 No. 3, pp. 137-142. https://doi.org/10.1108/MI-10-2013-0056