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Author: search.filters.author.Kumari, SapnaSubject: search.filters.subject.Piezoelectricity

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    Role of sintering temperature in tailoring the electrical properties of 0.98KNNS�0.02BNZSH piezoelectric ceramics
    (Springer, 2023-02-16T00:00:00) Kumar, Amit; Kumari, Sapna; Kumar, V.; Kumar, Ashok; Goyal, P.K.; Aggarwal, Sanjeev; Arya, Anil; Sharma, A.L.
    Lead-free 0.98(K0.5Na0.5)(Nb0.96Sb0.04O3)�0.02(Bi0.5Na0.5)(Zr0.8Sn0.1Hf0.1)O3 (0.98KNNS�0.02BNZSH) perovskite ferroelectric ceramics have been designed and prepared through the traditional ceramic fabrication technique. To have an insight on the effects of sintering temperature (in the range from 1020 to 1110��C), the structural, microstructural, dielectric and ferro/piezoelectric properties of 0.98KNNS�0.02BNZSH ceramics are investigated systematically. The structural analysis has revealed a pure perovskite phase for sintering at different temperatures. The rhombohedral (R) and orthorhombic (O) phases coexist for sintering of 0.98KNNS�0.02BNZSH ceramic at 1080��C, while the rhombohedral phase dominates above 1080��C. The grains become more uniform and tightly packed when the sintering temperature is increased from 1020 to 1080��C. However, the grain size and the density have been revealed to be decreased for samples sintered above 1080��C. The conduction behavior of 0.98KNNS�0.02BNZSH ceramics has also been investigated using complex impedance spectroscopy. The optimum values of different dielectric and ferro/piezoelectric parameters for 0.98KNNS�0.02BNZSH ceramics sintered at 1080��C are obtained to be as the following: TC ~ 317��C, ?max ~ 7102, tan? ~ 0.10, ? ~ 4.49�g/cm3, d33 ~ 180 pC/N, and Pr ~ 16.7 �C/cm2. These findings show that crystallizability, density, and electrical properties are significantly influenced by the sintering temperature. � 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
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    Synthesis, phase confirmation and electrical properties of (1 ? x)KNNS?xBNZSH lead-free ceramics
    (Springer, 2022-02-02T00:00:00) Kumar, Amit; Kumari, Sapna; Kumar, V.; Kumar, Prashant; Thakur, Vikas N.; Kumar, Ashok; Goyal, P.K.; Arya, Anil; Sharma, A.L.
    In the present work, lead-free piezoelectric ceramics (Rx)(K0.5Na0.5)(Nb0.96Sb0.04O3)?x(Bi0.5Na0.5)(Zr0.8Sn0.1Hf0.1)O3 [abb. as (Rx)KNNS?xBNZSH, 0 ? x ? 0.04] were prepared via solid-state sintering technique. The thermal behavior of mixed powders has been investigated for x = 0, 0.02, and 0.04 using TGA-DSC analysis to estimate the calcination temperature. The structural, morphological, dielectric, ferroelectric and piezoelectric properties are analyzed through the appropriate characterization techniques. The X-ray diffraction (XRD) patterns demonstrate a pure perovskite phase structure for all the sintered samples. Further, the coexistence of rhombohedral to orthorhombic (R-O) phase is observed in ceramic sample with x = 0.02. The morphology of all the sintered samples exhibits an inhomogeneous, dense microstructure with the rectangular grain, while for x = 0.02, a relatively homogeneous distribution of grains is observed. BNZSH doping decreases the average grain size from 2.22 to 0.33�?m for x = 0 to x = 0.04, respectively. Owing to the presence of multiple-phase coexistence as well as the improved microstructure and enhanced dielectric properties (dielectric constant ?r = 1080, ?max = 5301; Curie temperature - TC ~ 317��C; dielectric loss - tan? ~ 6%) the ceramics with x = 0.02 has been found to have a large piezoelectric coefficient (d33) of ~180 pC/N, remnant polarization (Pr) ~ 16.7 �C/cm2 and coercive field (Ec) ~ 10.7�kV/cm. We believe it will expand the range of applications for KNN-based ceramics. � 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.