title: Origin of giant piezoelectric effect in lead-free K1-xNaxTa1-yNbyO3 single crystals.
abstract: A series of high-quality, large-sized (maximum size of 16 × 16 × 32 mm(3)) K1-xNaxTa1-yNbyO3 (x = 0.61, 0.64, and 0.70 and corresponding y = 0.58, 0.60, and 0.63) single crystals were grown using the top-seed solution growth method. The segregation of the crystals, which allowed for precise control of the individual components of the crystals during growth, was investigated. The obtained crystals exhibited excellent properties without being annealed, including a low dielectric loss (0.006), a saturated hysteresis loop, a giant piezoelectric coefficient d33 (d33 = 416 pC/N, determined by the resonance method and d33(*) = 480 pC/N, measured using a piezo-d33 meter), and a large electromechanical coupling factor, k33 (k33 = 83.6%), which was comparable to that of lead zirconate titanate. The reason the piezoelectric coefficient d33 of K0.39Na0.61Ta0.42Nb0.58O3 was larger than those of the other two crystals grown was elucidated through first-principles calculations. The obtained results indicated that K1-xNaxTa1-yNbyO3 crystals can be used as a high-quality, lead-free piezoelectric material.
authors.affiliation: Department of Physics, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Tian
authors.affiliation: Department of Physics, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Xiangda
authors.initials: X
authors.lastname: Meng
authors.affiliation: Department of Physics, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Chengpeng
authors.initials: C
authors.lastname: Hu
authors.affiliation: Department of Physics, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Peng
authors.initials: P
authors.lastname: Tan
authors.affiliation: Department of Physics, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Xilong
authors.initials: X
authors.lastname: Cao
authors.affiliation: Department of Physics, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Guang
authors.initials: G
authors.lastname: Shi
authors.affiliation: Department of Physics, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Zhongxiang
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: Condensed Matter Science and Technology Institute, Harbin Institute of Technology, Harbin 150001, China.
authors.forename: Rui
authors.initials: R
authors.lastname: Zhang