Thickness dependent dielectric properties of calcium copper titanate ceramics measured in a controlled atmosphere

Abstract

Abstract Phase pure CaCu3Ti4O12 CCTO ceramics are prepared by solid-state synthesis route. The effect of measuring atmospheres (air and dry N2) on the stability and reproducibility of electrical properties of CCTO as a function of sample thickness (as-prepared to thinned down) is investigated. As-sintered CCTO prepared at 1080 °C for 5 h with an initial thickness of 2.31–2.32 mm is reduced subsequently by fine grinding to 1.835 mm and then to 1.65–1.5 mm. Large inconsistency in the impedance spectra is observed when the samples are measured in air despite the thickness variations. Stable and reproducible dielectric properties are obtained in dry N2. A relatively closer resistivity (∼2 × 108 Ωcm at 23 °C in N2) regardless of the sample thickness suggests the absence of any barrier layer at the sample surface. Increased space charge accumulation at grain boundaries (GBs) leading to much larger dielectric constant (e′) was observed in air at 23 °C. A temperature (from 23 °C to 225 °C) and frequency (from 1 Hz to 1 MHz) independent and stable e′ is observed when samples are tested in N2. Much lower tan δ values with large e′ are observed for both as prepared (0.010 ± 0.001 with e′ of 9,663 ± 4 at 1.4 kHz) and the thinned down (0.015 ± 0.000 with e′ of 9,352 ± 5 and 4.5 kHz) samples at 23 °C in N2.