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An experimental and theoretical insights into the dielectric properties of (Li, Nd) co-doped ZnO ceramics Md. Zahidur Rahaman1,2,*

, Hidekazu Tanaka3, and A. K. M. Akther Hossain2

1

School of Materials Science and Engineering, University of New South Wales, Sydney 2052, Australia Department of Physics, Bangladesh University of Engineering and Technology, Dhaka 1000, Bangladesh 3 Institute of Scientific and Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan 2

Received: 28 July 2020

ABSTRACT

Accepted: 22 September 2020

In this work, we report the combined effect of donor (Nd) and acceptor (Li) codoping at the Zn site of ZnO ceramics on structural, microstructural, and dielectric properties. Combining experimental observations with DFT-based theoretical study, we have shown that before experimental fabrication DFTbased first principles study can be used as a good indication to have prior qualitative assessment of a dielectric medium. For implementing this objective, various Li and Nd co-doped ZnO ceramics have been synthesized through the conventional solid-state reaction route. Quantitative XRD analysis reveals the formation of wurtzite hexagonal structured ZnO having space group P63mc. Meanwhile, FESEM micrographs confirm the formation of randomly aligned non-uniform grains in size and shape. We show that the average grain size distribution and density of the studied compositions are two tuning factors to control the dielectric properties of these compounds. Though the value of dielectric constant is decreased with the increase in doping content, the optimum composition Nd0.005Li0.005Zn0.99O exhibits slightly lower dielectric constant ( 2066 at 1 kHz) than pristine ZnO but relatively very low dielectric loss ( 0.20 at 1 kHz) at room temperature than pure ZnO ceramics sintered at 1623 K. For understanding the dielectric relaxation mechanism in the studied ceramics, complex impedance spectra analysis has also been performed and discussed thoroughly. This study provides a new insight for further development of ceramic materials with improved dielectric properties.

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Springer Science+Business

Media, LLC, part of Springer Nature 2020

Address correspondence to E-mail: [email protected]; [email protected]

https://doi.org/10.1007/s10854-020-04533-x

J Mater Sci: Mater Electron

1 Introduction At present, dielectric materials with colossal dielectric constant (CDC) have created great interest in the scientific community due to their potential applications as high energy density storage such as the ceramic power capacitors and the multi-layer ceramic capacitors (MLCC) [1]. An ideal dielectric material should have a number of characteristics including high-frequency stability, high temperature stability, colossal permittivity (CP) and considerably low dielectric loss [2]. However, it is still very difficult to maintain all of the above requirements in a single material. The giant dielectric property has been reported in rare-earth (RE) and transition metaldoped BaTiO3 [3],