Microstructural and high-temperature dielectric, piezoelectric and complex impedance spectroscopic properties of K0.5Bi0.5TiO3 modified NBT-BT lead-free ferroelectric ceramics. Issue 4 (April 2023)

• Record Type: Journal Article
• Authors: Mesrar, M.; Elbasset, A.; Echatoui, N.-S.; Abdi, F.; Lamcharfi, T.
• Is Part Of: Heliyon. Volume 9:Issue 4(2023)
• Publication Date: 2023-04
• Subjects: 0.73NBT-0.07BT-0.20KBT -- Solid state reaction method -- Reitveld refinement -- Dielectric properties -- Electromechanical properties; Research -- Periodicals; Medical sciences -- Periodicals; Natural history -- Periodicals; Social sciences -- Periodicals; Earth sciences -- Periodicals; Physical sciences -- Periodicals; 507.2
• DOI: 10.1016/j.heliyon.2023.e14761
• Languages: English
• ISSNs: 2405-8440

Abstract

Abstract: Solid solutions (1-x-y)(Na0.5 Bi0.5 )TiO3 -xBaTiO3 -y(K0.5 Bi0.5 )TiO3 with (x (mol.%) = 0, 7 and 100); y(mol.%) = 0, 20 and 100) compositions have been prepared by a conventional solid-state reaction method, and their structure, dielectric properties and depolarization temperature have been examined. At room temperature, X-ray diffraction (XRD) patterns reveal that the crystalline structure of the ceramics was perovskite. The morphotropic phase boundary (MPB) of the ternary system lying between rhombohedral ( R3c ) and tetragonal ( P4mm ) phases is in the range of (x (mol.%) = 7 and y (mol.%) = 20). The Raman-active modes for 0.73NBT-0.07BT-0.20KBT were separated and identified under the framework of group theory. SEM micrographs illustrate the quasi-uniform distribution of the grains, which are compact. The dielectric properties of the ceramics were studied in the frequency range of 1 kHz–100 kHz from ambient temperature to 600 °C. Dielectric measurements indicate that all ceramics show a diffuse phase transition near the temperature (Tm ) for diffusivity of the order of 1.4–1.7 and a shift of (Tm ) towards high temperatures. The resistance and capacitance of the various contributors (grain and grain boundary) in our samples are also discussed using a brick-layer model. Excellent piezoelectric properties for d33 = 146 pCN −1 and electromechanical coupling factors kp = 29.4% were observed at morphotropic phase boundary (MPB), which was assumed to be associated with the coexistence of rhombohedral and tetragonal phases and accurate grain size. This work establishes a new approach for improving lead-free piezoelectric ceramics based on 0.73NBT-0.07BT-0.20KBT.