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Nanocrystalline calcium titanate (CT) ceramic has been synthesized by a combination of solid-state reaction and high-energy ball milling. This nano-ceramic is characterized by X-ray diffraction (XRD), dielectric study and impedance spectroscopy. The XRD pattern shows single phase ceramic of orthorhombic symmetry. The frequency-dependent dielectric study shows that the dielectric constant is maximized at low frequencies and decreases with an increase in frequency. Impedance spectroscopy analyses reveal a non-Debye type relaxation phenomenon. A significant shift in impedance loss peaks toward the higher-frequency side indicates conduction in the material favoring the long-range motion of mobile charge carriers. The grain conduction effect is observed from the complex impedance spectrum by the appearance of one semicircular arc in Nyquist plot. It is also observed that the resistance decreases with an increase in temperature showing a negative temperature coefficient of resistance (NTCR). Various thermistor parameters have been calculated by fitting with Steinhart–Hart equation. The modulus plots represent the presence of temperature-dependent electrical relaxation phenomenon with the material. The frequency-dependent AC conductivity at different temperatures indicates that the conduction process is thermally activated. The activation energy has been calculated from an Arrhenius plot of DC conductivity and relaxation frequency.


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Frequency and temperature dependent electrical characteristics of CaTiO3 nano-ceramic prepared by high-energy ball milling

Show Author's information Subhanarayan SAHOOa,*( )Umasankar DASHbS. K. S. PARASHARcS. M. ALIa
School of Electrical Engineering, KIIT University, Bhubaneswar 751024, India
Center for Nanotechnology, KIIT University, Bhubaneswar 751024, India
School of Applied Sciences, KIIT University, Bhubaneswar 751024, India

Abstract

Nanocrystalline calcium titanate (CT) ceramic has been synthesized by a combination of solid-state reaction and high-energy ball milling. This nano-ceramic is characterized by X-ray diffraction (XRD), dielectric study and impedance spectroscopy. The XRD pattern shows single phase ceramic of orthorhombic symmetry. The frequency-dependent dielectric study shows that the dielectric constant is maximized at low frequencies and decreases with an increase in frequency. Impedance spectroscopy analyses reveal a non-Debye type relaxation phenomenon. A significant shift in impedance loss peaks toward the higher-frequency side indicates conduction in the material favoring the long-range motion of mobile charge carriers. The grain conduction effect is observed from the complex impedance spectrum by the appearance of one semicircular arc in Nyquist plot. It is also observed that the resistance decreases with an increase in temperature showing a negative temperature coefficient of resistance (NTCR). Various thermistor parameters have been calculated by fitting with Steinhart–Hart equation. The modulus plots represent the presence of temperature-dependent electrical relaxation phenomenon with the material. The frequency-dependent AC conductivity at different temperatures indicates that the conduction process is thermally activated. The activation energy has been calculated from an Arrhenius plot of DC conductivity and relaxation frequency.

Keywords:

high-energy ball milling, dielectric study, impedance spectroscopy, thermistor, conductivity
Received: 19 June 2013 Revised: 15 July 2013 Accepted: 21 July 2013 Published: 07 September 2013 Issue date: September 2013
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Publication history

Received: 19 June 2013
Revised: 15 July 2013
Accepted: 21 July 2013
Published: 07 September 2013
Issue date: September 2013

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© The author(s) 2013

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