Processing, dielectric and electrical characteristics of strontium-modified Ca1Cu3Ti4O12.

In the present paper, the strontium (Sr)-modified Ca₁Cu₃Ti₄O₁₂ ceramic (further termed as CSCTO) has been fabricated by a conventional cost-effective ceramic route. The prepared sample is characterized to obtain the relationship between the structural and electrical properties in a wide frequency (10³-10⁶ Hz) and temperature (25-315 °C) ranges. X-ray diffraction spectra depict a single-phase formation of the compound, crystallized in the cubic system. The dielectric relaxation mechanism and electrical properties of CSCTO have been revealed by studying frequency and temperature dependence of dielectric parameters (ε_r and tanδ) by dielectric and impedance spectroscopy. The temperature-dependant dielectric constant plots depict that at frequency 1 kHz, the compound has very high dielectric constant (order of 10⁴) and relatively low tangent loss. The occurrence of ultra high dielectric constant of the compound may be due to the space charge polarization, interface and Maxwell-Wagner dielectric relaxation around low frequencies and high-temperature range. The contributions of grains in resistive and capacitive properties of the material can be obtained from the Nyquist plot. It is interesting to note that at room temperature, polarization loop (P ~ E hysteresis loop) of the sintered CSCTO showed lossy behavior. The use of TiO₂ and CuO₂ nano-sized powders in the starting stage of sample preparation with micron size of CaCO₃ and SrCO₃ powder promotes the kinetics of quick conventional solid state reaction at a microscopic level, that favors above possible mechanisms. [ABSTRACT FROM AUTHOR]