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Structural, dielectric and electrical properties of pyrochlore-type Gd2Zr2O7 ceramic Saurabh K. Sharma1, Hari S. Mohanty2,4, Dillip K. Pradhan2, Ajay Kumar3, Vivek K. Shukla3, Fouran Singh1, and Pawan K. Kulriya1,* 1

Materials Science Group, Inter-University Accelerator Centre, New Delhi 110067, India Department of Physics and Astronomy, National Institute of Technology, Rourkela, Odisha 769008, India 3 School of Vocational Studies and Applied Science, Gautam Buddha University, Greater Noida, Uttar Pradesh 201312, India 4 Present address: Department of Basic Science and Humanities, GIET University, Gunupur, Odisha 765022, India 2

Received: 10 July 2020

ABSTRACT

Accepted: 16 October 2020

This work reports on the dielectric and electrical properties of a single-phase polycrystalline pyrochlore structured Gd2Zr2O7 ceramics with a highly dense and compact microstructure. X-ray diffraction along with Raman spectroscopic studies confirmed the formation of the pyrochlore phase; while the electron microscopy investigations showed the uniformly distributed and densely packed micrometer-sized grains. The relaxation phenomena and conduction processes in Gd2Zr2O7 analyzed using complex impedance spectroscopy which showed the appearance of low-frequency dielectric dispersion suggesting the dominance of conduction by oxygen ions. Observation of double semi-circular arcs in the Nyquist plots confirms that both grains and grain boundaries contribute to the electrical impedance of Gd2Zr2O7. The temperature-dependent ac conductivity studies on Gd2Zr2O7 followed the Jonscher’s power law exhibited a strong dispersive behavior at the low temperature (\ 300 °C) over the whole frequency region; whereas a weak dispersive nature observed at the higher temperature in the higher frequency region. An enhanced conductivity with relaxation phenomenon at elevated temperature is attributed to the transition from prolonged hopping to short-range ionic transportation. The increase in the ac conductivity with temperature reveals that Gd2Zr2O7 pyrochlore has a negative coefficient of resistance. Because of the good control of the electrical transport properties of Gd2Zr2O7 ceramic on its structure, it could be further exploited for the development of advanced solid-electrolytes for solid oxide fuel cells.

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Springer Science+Business

Media, LLC, part of Springer Nature 2020

Address correspondence to E-mail: [email protected]

https://doi.org/10.1007/s10854-020-04699-4

J Mater Sci: Mater Electron

1 Introduction Among the different complex oxides, pyrochlore structured compounds show extensive excellent physical and chemical properties, e.g. high tolerance to radiation damage, high melting point, high thermal stability, high ionic conductivity, low activation energy, and low thermal expansion coefficient [1]. These features of pyrochlore oxides make them a relevant candidate for various technological applications, for instance, high-temperature thermal barrier coating material [2], nuclear waste matrix material [3–5], catalysts [6, 7], solid