2007/10/08 by S. Krohns, P. Lunkenheimer, Stefan G. Ebbinghaus +2 · 1 citation
Chemistry · Engineering · Materials Science · Physics and Astronomy · #Chemistry #Condensed matter physics #Conductivity #Dielectric #Dielectric loss #Dielectric materials and actuators #Dielectric properties of ceramics #Dielectric spectroscopy #Electrode #Ferroelectric and Piezoelectric Materials #High-κ dielectric #Materials science #Nuclear magnetic resonance #Optoelectronics #Permittivity #Physics #Relaxation (psychology) #Resistive touchscreen #Single crystal #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1063/1.2902374
published as J. Appl. Phys. 103, 084107 (2008) · 9 pages, 7 figures
arxiv created 2007/10/08 · openalex publication_date 2008/04/15 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
In the present work, the authors report results of broadband dielectric spectroscopy on various samples of CaCu3Ti4O12 (CCTO), also including single-crystalline material, which so far was only rarely investigated. The measurements extend up to 1.3 GHz, covering more than nine frequency decades. We address the question of the origin of the colossal dielectric constants and of the relaxational behavior in this material, including the second relaxation reported in several recent works. For this purpose, the dependence of the temperature- and frequency-dependent dielectric properties on different tempering and surface treatments of the samples and on ac-field amplitude is investigated. Broadband spectra of a single crystal are analyzed by an equivalent circuit description by assuming two highly resistive layers in series to the bulk. Good fits could be achieved, including the second relaxation, which also shows up in single crystals. The temperature- and frequency-dependent intrinsic conductivity of CCTO is consistent with the variable range hopping model. The second relaxation is sensitive to surface treatment and, in contrast to the main relaxation, is also strongly affected by the applied ac voltage. Concerning the origin of the two insulating layers, we discuss a completely surface-related mechanism by assuming the formation of a metal-insulator diode and a combination of surface and internal barriers.