Frequency dependent study on dielectric, impedance and modulus behavior of bismuth vanadate ceramics Sukhanidhan Singh, Abhinav Yadav, Manisha Kumari, P.M. Sarun ⇑ Functional Ceramics Laboratory, Department of Physics, Indian Institute of Technology (Indian School of Mines), Dhanbad, Jharkhand 826004, India article info Article history: Received 24 February 2020 Received in revised form 16 May 2020 Accepted 19 May 2020 Available online xxxx Keywords: Vanadate Structural Microstructural Dielectric Impedance study abstract Bismuth vanadate (BiVO 4 : BVO) ceramics is synthesized by solid state reaction (SSR) technique sintered at 750 °C for 4 h. BVO exhibits monoclinic crystal structure of space group I2/b as obtained from the XRD analysis. Field emission scanning electron microscopy (FE-SEM) confirms the microstructural property, which reveals that, the grains have clear grain boundaries with least porosity and they are highly dense. For the investigation of dielectric and electrical properties of BVO at a temperature (230–390 °C) and fre- quency (300 Hz–1 MHz) range are chosen. The results show that, dielectric constant (e 0 ) is dependent on temperature variation. At 300 Hz, BVO exhibits very high dielectric constant 5651 at 390 °C. Impedance and modulus analysis confirm the temperature dependent relaxation and non-Debye behavior of the material, respectively. Activation energy associated with imaginary part of impedance is 0.49 eV. Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the Third International Con- ference on Materials Science (ICMS2020). 1. Introduction With the development of modern electronic devices, lead- containing dielectric materials have been profusely used in minia- turization, integration and high energy density storage, due to their excellent dielectric and piezoelectric properties [1–3]. But studies have proved that the residual of lead-containing materials is very toxic and hazardous for the environment and living beings. Hence, it is a warming topic to replace lead-containing toxic dielectric materials to lead-free non-toxic dielectric materials [4]. Many researchers are continuously working to fulfill the requirement. BVO is a lead-free and non-toxic oxide material of the Scheelite family (ABO 4 ) with a monoclinic crystal structure. In literature, four different crystallographic phases of bismuth vanadate are reported, orthorhombic (pucherite), zircon-type (dreyerite), scheelite monoclinic (clinobisvanite) and scheelite tetragonal phase. Scheelite tetragonal structure of bismuth vanadate is an unstable compound and its availability in any sort of naturally occurring minerals is not reported whereas rest of the three phases of bismuth vanadate are available naturally [5,6]. There is a rever- sible phase transition (ferroelastic to paraelastic) that occurs between scheelite monoclinic structure and scheelite tetragonal structure at about 255 °C. After heat treatment of 400–500 °C and room temperature cooling irreversible phase transition occur from tetragonal zircon-type structure to monoclinic BVO. BVO can be prepared by co-precipitation reaction followed by calcina- tion or by solid-state reaction technique [7,8]. The industrial appli- cations are only achievable for these ceramic materials which show stable dielectric characteristics with the change in surround- ing temperature. Dielectric properties of BVO ceramics is studied with variations of temperature and frequency. Excellent results have been obtained because of which BVO may have many impor- tant applications such as photocatalysis, in solar fuels, dielectrics, high temperature conductors, high performance pigment in the coatings available commercially and plastics industries. [9–14]. Scheelite monoclinic is very good visible-light-driven semiconduc- tor photocatalyst [8]. Monoclinic phase of BVO represents a high dielectric constant. Due to its excellent dielectric constant BVO is also a very important compound to use in capacitor applications. In the present work, structural analysis is done by X-ray diffrac- tion (XRD) and for the observation of microstructure of freshly fractured BVO sample sintered at 750 °C, field emission scanning electron microscope (FE-SEM) was used. Dielectric parameters (e 0 , tan d), complex impedances and complex modules were mea- sured by LCR meter. The role of grains and grain boundaries are explained in temperature and frequency range from 230–390 °C and 300 Hz–1 MHz, respectively using Nyquist plot. https://doi.org/10.1016/j.matpr.2020.05.492 2214-7853/Ó 2020 Elsevier Ltd. All rights reserved. Selection and Peer-review under responsibility of the scientific committee of the Third International Conference on Materials Science (ICMS2020). ⇑ Corresponding author. E-mail address: sarun@iitism.ac.in (P.M. Sarun). Materials Today: Proceedings xxx (xxxx) xxx Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr Please cite this article as: S. Singh, A. Yadav, M. Kumari et al., Frequency dependent study on dielectric, impedance and modulus behavior of bismuth vana- date ceramics, Materials Today: Proceedings, https://doi.org/10.1016/j.matpr.2020.05.492