Effect of Bi 3+ substitution on structural and electrical properties of polycrystalline NiWO 4 nanoparticles
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Effect of Bi3+ substitution on structural and electrical properties of polycrystalline NiWO4 nanoparticles H Hitha1,2, Mathew John1, Anjaly Jose1, Soumya Kuriakose3, and Thomas Varghese1,*
1
Nanoscience Research Centre (NSRC), Department of Physics, Nirmala College, 686 661 Muvattupuzha, Kerala, India Department of Physics, Newman College, 685584 Thodupuzha, Kerala, India 3 Department of Physics, St. Peters College, Kerala 682311 Kolencherry, India 2
Received: 20 July 2020
ABSTRACT
Accepted: 7 October 2020
Pristine- and Bi3?-doped NiWO4 nanoparticles are synthesized by direct chemical precipitation. The structural properties are investigated using various characterization techniques. The electrical properties of pure and Bi3?-doped NiWO4 samples are analysed with the help of dielectric permittivity, dissipation factor, impedance and electric modulus. Nyquist plots along with the equivalent circuits are used to analyse the relaxation and conduction mechanism of pure and Bi-doped NiWO4. Doping of Bi3? ion changes the structural and electrical properties of NiWO4 samples. With Bi3? doping, the conductivity of NiWO4 is increased along with variation in the conduction mechanism. Current work constitutes the first report on the study of electrical properties of Bi3?-doped NiWO4 nanoparticles.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Nickel tungstate is one of the members of isomorphous series of transition metal tungstates represented by MWO4 [M = Zn, Mn, Cr, Fe, Co] having small cations. The complex electronic structure of transition metal tungstates offers unique physical and chemical properties for potential applications. Thermo-physical, DC conductivity and dielectric measurements of these transition metal tungstates are mentioned in the literature [1–6]. Nickel tungstate with a wolframite structure is considered as an important candidate for the fields of sensors, catalysis and photovoltaic electrochemical cells. NiWO4 is a
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https://doi.org/10.1007/s10854-020-04630-x
p-type conducting material below 660 K. Literature reports a conductivity of 10- 7 – 10- 3 S/cm for the nickel tungstate at different temperatures [7–10]. The difference in conduction and electrical properties of polycrystalline NiWO4 from a single crystal NiWO4 is reported in the literature [9]. Many works have been reported with improved electrical properties of NiWO4 for supercapacitors and electrocatalyst [11–15]. In addition, modification of the electrical properties of NiWO4 nanoparticles by doping and the formation of nanocomposites are also investigated [16–18]. One of the useful methods to accomplish changes in structural and electrical properties of
J Mater Sci: Mater Electron
semiconductor materials is doping, which alters the structural matrix of the materials. Cobalt doping can be used to enhance the electrical conductivity of NiWO4, and its application as electrocatalyst [17]. In the present work, effect of Bi3?-doping on the struc
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