Dielectric, ferroelectric, and strain properties of lead-free (1−y)BNT–yST ceramics

• Published in: Journal of materials science. Materials in electronics 2020-04, Vol.31 (7), p.5667-5673
• Main Authors: Ullah, Amir, Ullah, Aman, Ullah, Mateen, Zeb, Aurang, Khan, Zeeshan, Ikram, M., Ullah, Hamd, Kim, Ill Won
• Format: Article
• Language: English
• Subjects: Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Coercivity; Crystal structure; Dielectric properties; Electric fields; Ferroelectric materials; Ferroelectricity; Grain size; Lead free; Materials Science; Morphology; Optical and Electronic Materials; Temperature
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-020-03133-z

Lead-free ceramics (1− y ) (Bi 1/2 Na 1/2 )TiO 3 – y SrTiO 3 (1− y )BNT– y ST with y  = 0, 0.1, 0.20, 0.25, 0.28, 0.30, and 0.32 were synthesized via a solid-state reaction process. A uniform grain morphology was obtained, and the mean grain size was around 2.0 μm for y  = 0, which decreased slightly for y  > 0. The undoped compound displayed a crystal structure with rhombohedral symmetry, and increasing amounts of ST gradually transformed the material to cubic phase. The maximum dielectric constant temperature ( T m ) was observed to decrease from 305 °C for sample y  = 0 to 135 °C for sample y  = 0.30. Remnant polarization ( P r ) decreased with increasing ST, and the ferroelectric loops narrowed. The coercive field ( E c ) was also observed to decrease with enhanced ST content; however, E c and P r increased for y  = 0.30. The electric field-induced strain gradually increased up to y  = 0.28 but decreased for y  > 0.28. The loops of strain became slimmer and saturated with increasing ST ratio to attain the maximum dynamic strain of 624 pm/V.