Impact of (Zr, Cu) Ion Substitution on the Optical, Dielectric, and Impedance Behavior of BiFeO 3
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Impact of (Zr, Cu) Ion Substitution on the Optical, Dielectric, and Impedance Behavior of BiFeO3 A. Sathiya Priya 1
&
D. Geetha 1
Received: 4 August 2020 / Accepted: 5 November 2020 # Sociedade Brasileira de Física 2020
Abstract In this paper, we report about the enhanced optical and dielectric properties of (Zr, Cu) dual-doped ceramics prepared by costeffective sol-gel method. The variation in optical and electrical parameters with increased Zr concentration was studied in detail. The UV–visible spectra showed absorption peaks at 350 nm and 440 nm for all the samples. The optical bandgap energy of the Bi1-xZrxFe0.98Cu0.02O3 system was found to decrease from 2.41 to 1.78 eV as a measure of Zr concentration. Reduced bandgaps show the potential of these ferrites in visible light photocatalysis. With increase in frequency, the dielectric constant and dielectric loss were found to decrease without any resonance peak while the electrical conductivity increased. At 1 MHz, the dielectric constant (ε′) value as high as 8702 has been achieved for the doped sample. Impedance spectroscopy confirmed the semiconductor behavior of the ferrites. The Nyquist plots favor the non-Debye relaxation process. A remarkable improvement in the dielectric response of the (Zr, Cu) dual-doped BiFeO3 is observed which favors reduced eddy current loss thereby increasing its application in high-frequency devices. Keywords Doped BiFeO3 . Band gap . Dielectric constant . Impedance . Nyquist plot
1 Introduction Perovskite bismuth ferrite, BiFeO3 (BFO), is a promising multiferroic material, intensively studied owing to its potential applications in information storage, spintronics, smart sensors, lead-free ferroelectric photovoltaic, photocatalysis, etc. [1–4]. For the past decade, tremendous research has been focused on the improvement of multiferroic properties of BFO by simultaneous substitution of A and B sites by transition/rare earth metal ions [5–20]. Earlier reports have confirmed that codoping in BFO has resulted in enhancement of dielectric properties and lowering of dielectric loss [15–22]. Pr and Ti codoping in BFO has resulted in improved dielectric properties which has been attributed to the reduction in oxygen vacancies by the substituted ions [23]. Moreover, weaker frequency dependence of εo and tan δ has been witnessed. Coondoo et al. [20] have realized significant increase in dielectric constant by La and Nd substitution at the Bi and Fe sites, respectively.
* D. Geetha [email protected] 1
Department of Physics, Madras Institute of Technology, Anna University, Chennai 600044, India
They have accredited the lanthanide substitution for suppressing the formation of oxygen vacancies in BFO. Ahmad et al. [21] have studied the effect of Yb and Co co-doping of BFO and have reported enhanced dielectric properties. Similar results have been observed in Er/Ti co-doped BFO [22] and Ba and Ho co-doped BFO [24], and decrease in oxygen vacancies has been established as the reason for that. Moreover, codoping of transi
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