Nonstoichiometric effect of A-site complex ions on structural, dielectric, ferroelectric, and electrostrain properties of bismuth sodium titanate ceramics. Issue 23 (1st December 2021)

• Record Type: Journal Article
• Authors: Zhang, Amei; Jing, Ruiyi; Zhuang, Meng; Hou, Hongping; Zhang, Leiyang; Zhang, Jie; Lu, Xu; Yan, Yangxi; Du, Hongliang; Jin, Li
• Is Part Of: Ceramics international. Volume 47:Issue 23(2021)
• Page Start: 32747
• Page End: 32755
• Publication Date: 2021-12-01
• Subjects: Nonstoichiometry -- Dielectric -- Electrostrain -- Polarization -- BNT; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2021.08.171
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: To investigate the nonstoichiometric effect of (Bi0.5 Na0.5 )TiO3 (BNT) ceramics on their properties, we propose a novel chemical expression, (Bi0.5+ x Na0.5−3 x )TiO3 . The nonstoichiometric effect of BNT can be explored in compounds with this composition without being hampered by the charge imbalance problem. With x ranging from −0.02 to 0.02, we find that the morphological, dielectric, ferroelectric, and electrostrain properties differ considerably between Na-rich and Bi-rich ceramic samples. The average grain size (AGS) increased significantly in Na-rich samples compared to that in stoichiometric BNT, while it decreased slightly in Bi-rich samples. The dielectric characteristics measured from 30 °C to 500 °C indicate that conductivity is activated in Na-rich nonstoichiometric samples but is effectively suppressed in Bi-rich nonstoichiometric samples. The ferroelectric properties also show the same trend. In Na-rich samples, elliptical polarization against electric field ( P - E ) hysteresis loops were detected, indicating a conductive character induced by high electric field loading. However, saturated P - E loops are observed in Bi-rich samples with well-inhibited conductivity. Furthermore, compared to stoichiometric BNT and nonstoichiometric x = 0.02 Bi-rich samples, (Bi0.5+ x Na0.5−3 x )TiO3 samples with x = 0.01 exhibit higher electrostrain from 30 °C to 150 °C. Based on the assumption of charge balance, our findings indicated that the presence of 1 mol% excess Bi would facilitate significant improvement in the dielectric, ferroelectric, and electrostrain properties of BNT and BNT-based systems.