Piezoelectric Properties of (1-x)(K_0.52Na_0.48)_1-xLi_xNbO₃-x (Bi_0.5Na_0.5)_0.9Ca_0.1TiO₃ with Higher Curie Temperature

Abstract

The polymorphic phase transition (PPT) near room temperature can induce enhanced electrical properties of KNN-based lead-free piezoelectric ceramics, limiting their temperature stability. In this paper, the 0.98(K_0.52Na_0.48)_1-x Li _x NbO_3–0.02(Bi_0.5Na_0.5)_0.9 Ca_0.1TiO₃ (KNLN _x -BNCT) lead-free piezoelectric ceramics were prepared by the conventional sintering technique, and the electrical properties and phase structure can be tailored by modifying Li content. The polymorphic phase transition (PPT) from orthorhombic and tetragonal phase around room temperature was identified in the composition range 0.01 ≤ x ≤ 0.02, resulting in improved electrical properties (d ₃₃∼262 pC/N, k _p ∼ 0.36, ϵ _r ∼ 715, and tan δ∼ 0.03). Moreover, KNLN _x -BNCT (x0.02) ceramics with tetragonal structure possess a pertinent temperature stability and a broader application range owing to its higher T _C (>400°C).

Keywords:

• Lead-free piezoelectric ceramic
• Curie temperature
• Piezoelectric properties
• Temperature stability

Acknowledgment

This work was supported by National Science Foundation of China (NSFC Nos. 50772068, 50972001 and 51272164) and Foundation of Doctor Training Program in University and College in China (Nos. 20030610035, and 20080610020).