Effect of Li + Ion Substitution on Structural and Dielectric Properties of Bi 0.5 Na 0.5-x Li x TiO 3 Nanoceramics
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Effect of Li+ Ion Substitution on Structural and Dielectric Properties of Bi0.5Na0.5‑xLixTiO3 Nanoceramics Susheel Patel1 · Pallavi Saxena1 · P. Choudhary1 · A. Yadav1,2 · V. N. Rai1 · A. Mishra1 Received: 7 July 2020 / Accepted: 7 November 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract In this study, we fabricated Li+ doped Bi1/2Na1/2-xLixTiO3 [BNLT] (x = 0.0, 0.025, 0.05, 0.075 and 0.1) nanoceramics by double sintered solid-state reaction method. The structural, optical, dielectric and ferroelectric properties of the ceramic samples have been investigated. X-ray diffraction results confirm that all the ceramics are pure phase perovskite with rhombohedral structure and R3c space group. The different bonds (Bi3+/Na+/Li+ and Ti4+–O) related to vibrational modes have been studied by analyzing the Raman spectra. The observed optical band gaps were found to decrease from 3.37 to 3.31 eV as the Li+ doping is increased. The dielectric permittivity (ε′) and loss factor (tan δ) reduces with a raise in the frequency whereas at elevated frequency both became constant. Dielectric plot show irregular trends with increasing Li+ ion replacement. The ac conductivity is found to rise with a higher frequency. Modulus and complex impedance study point toward the continuation of equal grain and grain boundary assistance in BNLT ceramics. The P–E hysteresis loops verify the ferroelectric nature of all the ceramics. Keywords Solid-state reaction route · X-ray diffraction · Raman spectroscopy · Dielectric properties · Polarization
1 Introduction Bi1/2Na1/2TiO3 (BNT) based ceramics have been found as the most fascinating and lead-free novel materials with a large number of physical properties since the last decades. Na+ ions present in BNT play a crucial role because of its volatile nature, which is also discussed by several research groups [1, 2]. Crystal chemistry of BNT based materials reveals rhombohedral type structure. Due to their large residual polarization ( Pr = 38 μC/cm2), BNT materials have attracted considerable attention. Nevertheless, it is very difficult to obtain an uncontaminated BNT ceramic due to its elevated conductivity and large coercive field (EC = 73 kV/ cm) at room temperature. It causes tribulations in the process * Susheel Patel [email protected] * Pallavi Saxena [email protected] 1
Materials Science Laboratory, School of Physics, Vigyan Bhavan, Devi Ahilya University, Khandwa Road Campus, Indore 452001, India
Department of Physics, Medi–Caps University, Pigdamber, Indore 453331, India
2
of polarization and therefore results in weak piezoelectric properties [3]. Bismuth-based perovskite materials are leadfree ferroelectric materials that change from relaxor (weakly polar state) to ferroelectric state due to the phase transition and generate a large induced electric field. It has various technological applications particularly in electronic devices such as piezoelectric actuators, piezoelectric ultrasonic transducers, micro-electromecha
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