Abstract
In this work, effect of vanadium doping of CaCu<sub>3</sub>Ti<sub>4</sub>O<sub>12</sub> (CCTO) on microstructure and complex dielectric constant over wide frequency (100 Hz-1 MHz) and temperature (0°C – 160°C) ranges has been studied. The vanadium doping of CCTO system results in an increase of grain size, the grains being surrounded by melted-like grain boundaries. Real parts of dielectric constant of all samples are similar at low frequency (<1 kHz). In doped samples, above 1 kHz, a relaxation appears which is evidenced by a drop of real part of permittivity and a peak of its imaginary part. This relaxation phenomenon is very significant at relatively low doping rates and then decreases again as vanadium content increases. AC conductivity behavior of vanadium-doped CCTO can be divided in three regions depending on conduction processes. The calculated activation energies were close to 0.46 eV.
Highlights
Research on new high permittivity materials for the enhancement of the performance of capacitors has led to the discovery of a new class of materials based on perovskiterelated compounds like the prominent CaCu3Ti4O12 (CCTO)
It seems more or less accepted that the origin of the high dielectric constant is due to extrinsic effects, like Surface Barrier Layer Capacitance (SBLC) [6] or Internal Barrier Layer Capacitance (IBLC) [1, 7, 8]
Vanadium doping of CCTO increases its lattice parameter and the grain size by partial substitution of titanium
Summary
Research on new high permittivity materials for the enhancement of the performance of capacitors has led to the discovery of a new class of materials based on perovskiterelated compounds like the prominent CaCu3Ti4O12 (CCTO) This material shows a number of interesting properties with the possibility of a large number of technological applications in the field of microelectronics [1]. It seems more or less accepted that the origin of the high dielectric constant is due to extrinsic effects, like Surface Barrier Layer Capacitance (SBLC) [6] or Internal Barrier Layer Capacitance (IBLC) [1, 7, 8] This last theory reported that semi-conductor grains and insulating grain boundaries lead to this large value of permittivity. To compensate the charge balance, Ti3+ would appear within the material, affecting the conductivity [13]
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