Synthesis and investigation of properties of nanostructured cubic PMN ceramics for possible applications in electronics
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Synthesis and investigation of properties of nanostructured cubic PMN ceramics for possible applications in electronics Kakali Sarkar1 · Vivek Kumar2 · Siddhartha Mukherjee3 Received: 30 April 2020 / Accepted: 10 July 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The pure phase of Pb(Mg1/3Nb2/3)O3 was synthesized by two-stage chemical process at 800 °C. Thermal analysis of precursors was done by TG-DSC. XRD, Raman spectroscopy, FESEM and HRTEM analyses were done to characterize synthesized material and also to observe the microstructure. XRD studies revealed the formation of pure crystalline PMN ceramics (JCPDS PDF# 00-081-0861) having crystallite size around 28 nm. The particle size was examined to be around 19 nm by HRTEM. The nanocrystalline PMN ceramics exhibited a bandgap around 3.28 eV using diffuse reflectance spectroscopy. Dielectric nature was inspected using impedance analyzer between 40 Hz and 110 MHz. Dielectric constant ( 𝜖r ) and tan𝛿 were investigated where unusual negative values of 𝜖rwere observed beyond 41.26 MHz. A peak in tan𝛿 near 41.26 MHz was also obtained.
1 Introduction Pb(Mg1/3Nb2/3)O3 (PMN) was discovered in 1958 [1]. These have been comprehensively investigated due to extraordinary properties such as dielectric relaxation phenomena and giant weak-field dielectric permittivity over an extensive temperature range. The properties are interesting and superior too, often called relaxor ferroelectric properties. Due to this attractive behaviour, PMN ceramics find their applications in capacitors, actuators and electro-optic transducers [2–5]. Earlier conducted experiments reveal that the perovskite-structured PMN exhibits fine dielectric behaviour but reduction in 𝜖r (dielectric constant) was noticed because of pyrochlore [6–8]. This was basically caused by volatilization of PbO, small dispersion of MgO and the considerable differences in reactive temperatures of Pb–Nb and Pb–Mg [8–10]. Hence, several innovative procedures [11–13] were adopted to reduce pyrochlore phase. Pyrochlore-free Pb(Mg1/3Nb2/3)O3 was also synthesized by a process where * Vivek Kumar [email protected] 1
Department of Metallurgical and Material Engineering, Jadavpur University, Kolkata 700032, India
2
Aryabhatta Center for Nanoscience and Nanotechnology, Aryabhatta Knowledge University, Patna 800001, India
3
Dr. M. N. Dastur School of Materials Science and Engineering, Indian Institute of Engineering Science and Technology, Howrah 711103, India
chemical routes and solid-state reactions of mixed oxides were used [11, 14–16]. In recent years, people have shown interest in preparing single-phase Pb(Mg1/3Nb2/3)O3 powders and furthermore in the sintering and dielectric behaviour of PMN-based ceramics [14, 17, 18]. Mixed oxide route was traditionally used to synthesize Pb(Mg1/3Nb 2/3)O 3 (PMN) where the pure phase of the desired material was obtained at 950–1200 °C [19, 20]. The perovskite PMN was also prepared at 650–750 °C through columbite method [21]. In this pro
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