Effect of Lanthanum Doping on Ferroelectric and Strain Properties of 0.96Bi1/2(Na0.84K0.16)1/2TiO3-0.04SrTiO3 Lead-Free Ceramics

• Published in: Journal of electronic materials 2016-05, Vol.45 (5), p.2639-2643
• Main Authors: Tran, Vu Diem Ngoc, Ullah, Aman, Dinh, Thi Hinh, Lee, Jae-Shin
• Format: Article
• Language: English
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Electronics and Microelectronics; Instrumentation; Materials Science; Optical and Electronic Materials; Solid State Physics
• ISSN: 0361-5235; 1543-186X
• DOI: 10.1007/s11664-016-4448-y

Lead-free 0.96[Bi 1/2 (Na 0.84 K 0.16 ) 1/2 ] (1− x ) La x TiO 3 -0.04SrTiO 3 (BNKTLa x -ST, with x  = 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05) ceramics have been synthesized using a conventional solid-state reaction method and their phase transition, dielectric, ferroelectric, and strain properties investigated. X-ray diffraction patterns revealed formation of pure perovskite phase. A phase transition from coexistence of rhombohedral and tetragonal to a pseudocubic phase was observed at x  = 0.02. Polarization and bipolar strain hysteresis loops indicated that the ferroelectric order (FE) of BNKT-ST is significantly disrupted by lanthanum doping. The destabilization of the FE order results in degradation of the remanent polarization, coercive field, depolarization temperature ( T d ), electromechanical coupling factor ( k p ), and static d 33 , accompanied by large electric-field-induced strain of 0.34% at 60 kV/cm with normalized strain of d 33 *  =  S max / E max  = 600 pm/V at a critical composition of around x  = 0.02.