Composition range and electrical properties of the morphotropic phase boundary in Bi0.5(Na0.80K0.20)0.5TiO3-(Ba0.7Sr0.3)TiO3 system

• Main Authors: Jaita P., Watcharapasorn A., Jiansirisomboon S.
• Format: Article
• Language: English
• Published: 2014
• Online Access: http://www.scopus.com/inward/record.url?eid=2-s2.0-84880405631&partnerID=40&md5=8d1ce7b01d6d0cf080ce165a2756cedc; http://cmuir.cmu.ac.th/handle/6653943832/7148
• Institution: Chiang Mai University

The lead-free piezoelectric ceramic binary system of (1-x)Bi0.5(Na0.80K0.20)0.5TiO3-x(Ba0.7Sr0.3)TiO3 or (1-x) BNKT-xBST (with x ranging from 0.05 to 0.15 mol fraction) near the morphotropic phase boundary (MPB) has been investigated. The ceramics were synthesized by a conventional mixed-oxide method and sintered at 1125°C for 2 h. All BNKT-BST samples had relative density higher than 98% of their theoretical values. X-ray diffraction patterns showed that all compositions had a pure perovskite structure and BST effectively diffused into the BNKT lattice during sintering to form a solid solution. Crystal structure changed from rhombohedral-rich phase to tetragonal-rich phase with increasing BST content. Because of such MPB-like behavior, the highest dielectric (Tc = 325°C, e{open}r = 1827, tan δ = 0.0823) and piezoelectric performances (d33 = 225 pC/N) were obtained in the BNKT-0.11BST sample. © 2013 The Korean Institute of Metals and Materials and Springer Science+Business Media Dordrecht.