Composition range and electrical properties of the morphotropic phase boundary in Bi<inf>0.5</inf>(Na<inf>0.80</inf>K<inf>0.20</inf>)<inf>0.5</inf>TiO<inf>3</inf>-(Ba<inf>0.7</inf>Sr<inf>0.3</inf>)TiO<inf>3</inf> system

• Main Authors: Pharatree Jaita, Anucha Watcharapasorn, Sukanda Jiansirisomboon
• Format: Journal
• Published: 2018
• Online Access: https://www.scopus.com/inward/record.uri?partnerID=HzOxMe3b&scp=84880405631&origin=inward; http://cmuir.cmu.ac.th/jspui/handle/6653943832/47821
• Institution: Chiang Mai University

The lead-free piezoelectric ceramic binary system of (1-x)Bi 0.5 (Na 0.80 K 0.20 ) 0.5 TiO 3 -x(Ba 0.7 Sr 0.3 )TiO 3 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 (T c = 325°C, e{open} r = 1827, tan δ = 0.0823) and piezoelectric performances (d 33 = 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.