Large Field-Induced Strain Properties of Sr(K0.25Nb0.75) O3-Modified Bi1/2(Na0.82K0.18)1/2TiO3 Lead-Free Piezoelectric Ceramics

• Published in: Journal of electronic materials 2016-05, Vol.45 (5), p.2627-2631
• 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/s11664-016-4445-1

Lead-free piezoelectric ceramics with compositions of (1 −  x )Bi 1/2 (Na 0.82 K 0.18 ) 1/2 TiO 3  +  x Sr(K 0.25 Nb 0.75 )O 3 , which are abbreviated as (1 −  x )BNKT- x SKN with x  = 0, 0.01, 0.02, 0.03, 0.04, and 0.05, were synthesized using a conventional solid-state reaction method. The effects of SKN addition on the BNKT system were examined in terms of the phase transition, strain behavior, and ferroelectric and dielectric properties. X-ray diffraction revealed a single perovskite phase for all compositions. The results showed that with increasing SKN content, BNKT-SKN underwent a phase transition from the coexistence of rhombohedral and tetragonal phases to a tetragonal phase. The addition of SKN shifted the depolarization temperature, T d , to a lower temperature and enhanced the diffuseness of the dielectric peaks. The polarization and bipolar strain hysteresis loops of BNKT-SKN showed that the addition of SKN induced a ferroelectric to ergodic relaxor phase transition with a disruption of the ferroelectric order of pure BNKT. As a result, the strain of BNKT-SKN improved significantly with increasing SKN content and reached the highest value of a normalized strain, S max / E max, of 557 pm/V, when modified with 3 mol.% SKN.