Structural and impedance spectroscopic studies of spark plasma sintered CaCu3Ti4O12 dielectric ceramics: an evidence of internal resistive barrier effect

Abstract

A giant dielectric constant CaCu 3 Ti 4 O 12 ceramic was prepared by solid-state reaction route. Powders were spark plasma sintered at 1050°C for 30 min. Rietveld refined XRD pattern reveals the formation of pure phase cubic perovskite CCTO. The dielectric properties were characterized in a broad frequency range of 10 Hz-8 MHz at temperatures 20-120°C. The grain size of sintered pellets was found in range of 12-15 lm. Impedance spectroscopic analysis shows that the observed semicircle in the Cole-Cole plot was associated with grain boundary relaxation effect. This study reveals that there is an evidence of internal resistive barrier which responsible for a giant dielectric constant in CaCu 3 Ti 4 O 12 ceramic. An Arrhenius temperature dependent relaxation effect was observed in grain boundary. Using the characteristic frequency of relaxation peak, grain boundary capacitance was calculated to be 0.27 lF. It was found that on increasing the temperature, the resistance of grain boundaries was decreased rapidly as compared to that of the grains. The activation energy of grain boundary was calculated to be 0.165 eV.

Structural and dielectric properties of giant dielectric Na1/2Sm1/2Cu3Ti4O12 ceramics prepared by reactive sintering methods

“…Moreover, the SPS025 ceramic shows an average grain size of ∼ 500 nm, which is much smaller than that of the CS090 sample (∼ 5 µm). It is worthy to note that the grain sizes of the current samples are much smaller than those reported for the conventionally (> 10 µm) [15,21] and spark plasma (> 1 µm) [22] sintered CCTO ceramics. Figure 3 shows the elemental analysis in the grain and grain-boundary regions of the SPS025 and CS090 ceramics and the quantitative results are given in Table 1.…”

From Synthesis to Applications: Copper Calcium Titanate (CCTO) and its Magnetic and Photocatalytic Properties

“…In 2017, Kumar et al . obtained spark plasma sintered ceramics using a temperature of sintering of 1050 °C and a duration of 30 minutes.…”

“…Reprinted by permission from (Nature/springer/Journal of Materials science, Materials in Electronics) (Kumar et al.) – doi.org/10.1007/s10854‐016‐4418‐4 Copyright (2016) …”

“…In 2017, Kumar et al [48] obtained spark plasma sintered ceramics using a temperature of sintering of 1050°C and a duration of 30 minutes. The microstructure of the sintered ceramics ( Figure 20a) showed that microstructure has highly compacted grains with grain boundaries.…”