Effect of the Ag-Doping on the Phase Structural Evolution, Dielectric and Ferroelectric Properties of Lead-Free Niobate Ceramics

• Published in: Electronic materials letters 2022, 18(2), , pp.159-167
• Main Authors: Wang, Huining, Zhang, Zixin, Yang, QuanSen, Wang, Fangfang, Yan, Kang
• Format: Article
• Language: English
• Subjects: Anomalies; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Condensed Matter Physics; Crystal structure; Curie temperature; Doping; Ferroelectric materials; Ferroelectricity; Lead free; Low temperature; Magnetics and Photonics; Materials Science; Nanotechnology; Nanotechnology and Microengineering; Optical and Electronic Materials; Original Article - Electronics; Orthorhombic phase; Perovskite structure; Perovskites; Phase transitions; Physical properties; Piezoelectric ceramics; Room temperature; Solid phases; Temperature; 전자/정보통신공학
• ISSN: 1738-8090; 2093-6788
• DOI: 10.1007/s13391-021-00328-2

Ionic doping is an important approach to modification of crystal structure and physical properties of the piezoelectric ceramics. In this work, the lead-free piezoelectric ceramic (1- x )K 0.18 Na 0.74 Li 0.08 NbO 3 - x AgNbO 3 (abbreviated as KNLN- x AN, 0 ≤ x ≤ 0.8) was prepared by conventional solid-state reaction method. The effect of the Ag doping on the phase structure, dielectric and ferroelectric properties of the KNLN-based ceramics was investigated by the XRD, DSC, dielectric and ferroelectric characterizations. It is found that all KNLN- x AN ceramics show single phase in perovskite structure because the ionic radii of dopant Ag close to the average ionic size at the A-site in KNLN. The KNLN- x AN exhibits the rhombohedral to orthorhombic phase transition at room temperature and the Curie temperature ( T C ) decreases to low temperature with increasing x value. A narrow tetragonal phase region and a wide orthorhombic phase region form for the compositions with x  ≥ 0.4, indicating that the Ag doping stabilizes orthorhombic phase in wide temperature for the KNLN. A ferroelectric anomalies due to high electrical field induced phase transition is found in the sample with x  = 0.1. When x  = 0.4, high Curie temperature ( T C  = 380 °C), large remnant polarization ( P r  = 24.4 μC/cm 2 ) and high dielectric constant ( ε r  = 10,000 at 1 kHz) at T C are achieved. Graphical abstract