Structural, Piezoelectric and Dielectric Properties of K0.4Na0.6NbO3-Bi0.5Li0.5ZrO3-CaZrO3 Ternary Lead-Free Piezoelectric Ceramics.

He, Caiwang; Bai, Xudong; Wang, Jinchuan; Liu, Yunyi; Lu, Yang; Liu, Xiaokui; Xiang, Yunjie; Xu, Zunping; Chen, Yi

The Bi0.5Li0.5ZrO3 and CaZrO3 co-modified (K,Na)NbO3-based ceramics, with a formula of (0.98-x)K0.4Na0.6NbO3-xBi0.5Li0.5ZrO3-0.02CaZrO3, were designed to form a rhombohedral-tetragonal phase boundary, and a conventional solid-state sintering method was employed to prepare them. X-ray diffraction analysis revealed that a pure perovskite structure could be maintained in the studied composition range 0 ≤ x ≤ 0.05. Dielectric-temperature measurements were performed to further identify the phase structure of the ceramics, which was found undergoing a gradual evolution from an orthorhombic to a rhombohedral structure with increasing x. Furthermore, a rhombohedral-tetragonal phase boundary was observed to be formed at x = 0.035, near which enhanced piezoelectric properties were obtained, with piezoelectric constant d33 = 241 pC/N and planar electromechanical coupling coefficient kp = 0.37. Additionally, an investigation was conducted of the influence of Bi0.5Li0.5ZrO3 addition on the microstructure and paraelectric-ferroelectric phase transition of the ceramics as well. We believe that the findings in this current work can deepen our understanding of the role of Bi0.5Li0.5ZrO3 in the construction of a phase boundary and improvement of piezoelectric properties for (K,Na)NbO3-based ceramics.

PIEZOELECTRIC ceramics; LEAD-free ceramics; DIELECTRIC properties; X-ray diffraction; PHASE transitions; CERAMICS; MICROSTRUCTURE

Journal of Electronic Materials, 2020, Vol 49, Issue 7, p4364

0361-5235

Academic Journal

10.1007/s11664-020-08174-y