A Bimodal Grain Size Model for Predicting the Dielectric Constant of Calcium Copper Titanate Ceramics

Abstract

The bimodal distribution of grain size is frequently observed in calcium copper titanate (CaCu 3 Ti 4 O 12 or CCTO) ceramics that exhibit high dielectric constant. In this study, we propose an analytical model composed of grains of two different sizes to estimate the dielectric behavior of CCTO based on microstructural features. Important assumptions are (1) CCTO is a barrier layer dielectric and (2) the insulating layer thickness is the same in both large and small grains. Explicit expressions for the effective dielectric constant of serial, parallel, and logarithmic mixture models are given. When compared with experimental results, the present bimodal model appears to be acceptable for describing the dielectric behavior of CCTO.

Dielectric properties of soft chemical method derived CaCu3Ti4O12 thin films onto Pt/TiO2/Si(100) substrates

“…The low dispersion of the dielectric permittivity and the absence of any relaxation peak in tan ı indicate that an interfacial polarization of the Maxwell Wagner type and an interfacial polarization arisen from the electrode barrier are negligible in the film. The dielectric properties of the film obtained in the present work is comparable with that reported for polycrystalline CCTO thin films [10,38,8]. Dielectric permittivity as high as 2000 and dielectric loss of 0.05 has been reported for a polycrystalline CCTO thin film having 480 nm thickness produced by PLD [10].…”

“…doi:10.1016/j.jallcom.2010. 12.184 capacitance (IBLC) model [10]. This model is commonly accepted for ceramic samples 4 and also on thin films [11].…”

Microstructural and electrical properties of CaTiO3–CaCu3Ti4O12 ceramics

“…1 shows that the Cu 2+ cations exhibit planar four-coordinate geometry with four short Cu-O distances. CCTO ceramics have high ε values from 10 3 to 10 6 , depending on their fabrication process [9][10][11][12]. These ε values are invariant over a temperature range from 200 to 600 K. This indicates that CCTO is quite promising for ceramic capacitors, and it has attracted much interest.…”

Effect of Rapid Thermal Annealing on Sputtered CaCu3Ti4O12 Thin Films

“…However, giant dielectric constants have been measured for this material fabricated using various processes. [6][7][8][9][10] The dielectric properties of CCTO ceramics and thin films seem to be very sensitive to the preparation process. Much effort has focused on CCTO thin films fabricated using various methods, including pulsed-laser deposition (PLD), sol-gel, chemical solution deposition (CSD), and metal organic chemical vapor deposition (MOCVD).…”