Enhanced piezoelectric properties of Sr (1.7) (Na 0.5 Bi 0.5 ) 0.3 Bi 4 Ti 5 O 18 ceramics in the system Sr (2− x ) (Na 0.5 Bi 0.5 ) x Bi 4 Ti 5 O 18 (where 0 ≤ x ≤ 0.5)

• Published in: Journal of the American Ceramic Society 2019-07, Vol.102 (7), p.4082-4091
• Main Authors: Shet, Tukaram, Bhimireddi, Rajasekhar, Varma, Kalidindi B. R.
• Format: Article
• Language: English
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.16230

Fine powders synthesized via sol‐gel route were employed to fabricate Sr (2− x ) (Na 0.5 Bi 0.5 ) x Bi 4 Ti 5 O 18 (SNBT, where x = 0, 0.1, 0.25, 0.3, 0.4, and 0.5) ceramics. The composition ( x )‐dependent structural changes associated with SNBT ceramics were analyzed using X‐ray powder diffraction, transmission electron microscopy, and Raman spectroscopic techniques. Average grain size analyses carried out on the SNBT ceramics by scanning electron microscopy revealed an important role played by the dopants in inhibiting the grain growth. Dielectric constants and the Curie temperature of the ceramics were found to decrease and increase, respectively, with increase in x . The increase in Curie temperature with increase in x was attributed to the decrease in the tolerance factor. The specific composition ( x = 0.3) of the SNBT ceramics exhibited improved piezo‐ and ferroelectric properties associated with a higher Curie temperature (569 K). The piezoelectric coefficient ( d 33 ) and the planar electromechanical coupling coefficient ( k p ) of SNBT( x = 0.3) were enhanced by 25% and 42%, respectively, as compared to the undoped ceramics.