Pseudocubic-based polymorphic phase boundary structures and their effect on the piezoelectric properties of (Li,Na,K)(Nb,Sb)O3-SrZrO3 lead-free ceramics

• Published in: Journal of alloys and compounds Vol. 784; pp. 1334 - 1343
• Main Authors: Lee, Ku-Tak, Kim, Dae-Hyeon, Cho, Sung-Hoon, Kim, Jeong-Seog, Ryu, Jungho, Ahn, Chel-Woo, Lee, Tae-Ho, Kim, Gyeung-Ho, Nahm, Sahn
• Format: Journal Article
• Language: English
• Published: Lausanne Elsevier B.V 05.05.2019; Elsevier BV
• Subjects: (Li,Na,K)(Nb,Sb)O3-SrZrO3-based lead free piezoelectric ceramics; Ceramics; Charged particles; Crystal structure; Electronics; Ferroelectric materials; Ferroelectricity; Lead free; Phase boundaries; Piezoelectric properties; Piezoelectricity; Polymorphic phase boundary structure; Properties (attributes); Pseudocubic structure; Strontium zirconates; Pseudocubic structure; Piezoelectric properties; (Li,Na,K)(Nb,Sb)O3-SrZrO3-based lead free piezoelectric ceramics; Polymorphic phase boundary structure
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2019.01.011

CuO-added 0.96(LixNa0.5-xK0.5)(Nb1-ySby)O3-0.04SrZrO3 ceramics were sintered at 1020 °C for 6 h. Various crystal structures were synthesized in these specimens by controlling the Li2CO3 (x) and Sb2O5 (y) contents: pseudocubic, orthorhombic-pseudocubic polymorphic phase boundary (PPB), tetragonal-pseudocubic PPB, orthorhombic-tetragonal-pseudocubic PPB, and orthorhombic-tetragonal PPB structures. The pseudocubic structure developed in these specimens was similar to the R3m rhombohedral structure instead of the Pm3m cubic structure because the specimens with a pure pseudocubic structure showed good ferroelectric and piezoelectric properties. The piezoelectric properties of the specimens were influenced by their crystal structures. The specimen with the tetragonal-pseudocubic PPB structure showed the best piezoelectric properties because this structure was similar to the tetragonal-rhombohedral morphotropic phase boundary structure developed in Pb(Zr1-xTix)O3-based ceramics. In particular, the specimen with the tetragonal-pseudocubic PPB structure corresponding to x = 0.05 and y = 0.065 showed the largest d33 and kp values of 431 pC/N and 0.43, respectively. [Display omitted] •A schematic phase diagram of the (Li,Na,K)(Nb,Sb)O3-SrZrO3 ceramics was constructed.•The specimen with x = 0.05 has a tetragonal-rhombohedral PPB structure.•This specimen showed the highest piezoelectric properties (d33 = 431 pC/N and kp = 0.43).•This specimen maintains a high d33 value of 400 pC/N at 150 °C.