Synthesis, phase confirmation and electrical properties of (1 − x)KNNS−xBNZSH lead-free ceramics

• Published in: Journal of materials science. Materials in electronics 2022-03, Vol.33 (9), p.6240-6252
• Main Authors: Kumar, Amit, Kumari, Sapna, Kumar, V., Kumar, Prashant, Thakur, Vikas N., Kumar, Ashok, Goyal, P. K., Arya, Anil, Sharma, A. L.
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Materials Science; Optical and Electronic Materials
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-022-07798-6

In the present work, lead-free piezoelectric ceramics (R x )(K 0.5 Na 0.5 )(Nb 0.96 Sb 0.04 O 3 )− x (Bi 0.5 Na 0.5 )(Zr 0.8 Sn 0.1 Hf 0.1 )O 3 [abb. as (R x )KNNS− x BNZSH, 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 μm 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 ε r  = 1080, ε max  = 5301; Curie temperature - T C ~ 317 °C; dielectric loss - tan δ  ~ 6%) the ceramics with x = 0.02 has been found to have a large piezoelectric coefficient ( d 33 ) of ~180 pC/N, remnant polarization ( P r ) ~ 16.7 µC/cm 2 and coercive field ( E c ) ~ 10.7 kV/cm. We believe it will expand the range of applications for KNN-based ceramics.