PRESSURE INDUCED DIELECTRIC CONSTANT SUPPRESSION IN CaCu 3 Ti 4 O 12 CERAMICS.

High-dielectric-constant CaCu 3 Ti 4 O 12 (CCTO) ceramics were prepared using the conventional solid-state reaction method. The cubic perovskite structures were characterized using X-ray diffraction. The low frequency dielectric constants of these compounds are above 10,000 and keep constant in a wide temperature range. The origin of the larger dielectric constant is not fully understood, but many researchers attributed it to the internal barrier layer capacitance (IBLC) effect and the high dielectric constant in CCTO single crystal is attributed to the contribution of twin boundaries. In this letter, two sheets of CCTO ceramics were annealed under 1050°C for 10 min. A large pressure was applied on one of the two samples. The dielectric constants of the two annealed samples were greatly suppressed compared with the as-prepared one. We contribute this suppression to the loss of Cu contents and the reorientation of twin boundaries in CCTO ceramics. Our result confirms that the giant dielectric constant of CCTO is related with the IBLC effect. [ABSTRACT FROM AUTHOR]