Vertical morphotropic phase boundary in lead-free piezoelectric ceramics (K,Na,Li)NbO₃–BaZrO₃–(La,Na)TiO₃ system

Abstract

A morphotropic phase boundary (MPB) with temperature-independent behavior, the so-called vertical MPB was investigated in lead-free (K,Na,Li)NbO 3 -BaZrO 3 -(La,Na)TiO 3 ternary ceramic system. The specimens were synthesized by a conventional solidstate reaction method, and their crystal structures as well as their MPB were determined from X-ray diffraction patterns measured from room temperature to 300 C. The vertical MPB composition was determined to be 0.9025(K 0:45 Na 0:5 Li 0:05 ÞNbO 3 -0.09BaZrO 3 -0.0075(La,Na)TiO 3 and the Curie temperature was found to be about 195 C. It was successfully confirmed that ceramic samples of this system could be sintered in a reducing atmosphere. For lead-free piezoceramic applications of multilayer actuators using Ni inner electrodes, the results obtained in this work have important practical implications.

Large Piezoelectric Strain with Superior Thermal Stability and Excellent Fatigue Resistance of Lead-Free Potassium Sodium Niobate-Based Grain Orientation-Controlled Ceramics

“…For example, Saito et al and Messing et al developed the ⟨001⟩ c -oriented textured KNN-based ceramics, whose d 33 * is 2 times higher than that of the nontextured ceramic. , The other approach consists in the reduction of the PPT temperature to be just above room temperature. , However, this would cause a poor thermal stability for the properties. To solve this problem, a material with a vertical MPB is required. , For the piezoelectric ceramics with coexisting tetragonal–rhombohedral phases (i.e., MPB), with the switching of domains permitted in the angles of 71, 90, 109, and 180°, it will be easy to pole and will show significant macroscopic strain . An ideal method to further improve the piezoelectric properties of KNN-based ceramics would be the combination of these two approaches.…”

“…To solve this problem, a material with a vertical MPB is required. 22,33 For the piezoelectric ceramics with coexisting tetragonal−rhombohedral phases (i.e., MPB), with the switching of domains permitted in the angles of 71, 90, 109, and 180°, it will be easy to pole and will show significant macroscopic strain. 30 An ideal method to further improve the piezoelectric properties of KNN-based ceramics would be the combination of these two approaches.…”

Research on shear stress of electrorheological fluid containing piezoelectric powders

“…The most commonly used lead zirconate titanate (PZT) has the perovskite structure. However, with concerns about environmental pollution caused by PbO contained in lead-based piezoelectric materials, lead-free perovskite piezoelectric ceramics such as barium titanate, BaTiO 3 -based and potassium sodium niobate (K,Na)NbO 3 -based materials have been actively researched and developed (Baba et al, 2016;Karaki et al, 2007Karaki et al, , 2013Zhang et al, 2008). The coercive field of BaTiO 3 is approximately 0.2 kV/mm and that of KNN-based ceramics is approximately 0.9 kV/mm (Shrout and Zhang, 2007).…”

Effects of quenching on bending strength and piezoelectric properties of (Bi0.5Na0.5)TiO3ceramics

“…Thus, the development of leadfree piezoelectric materials is urgently required. As candidates for lead-free piezoelectric and ferroelectrics materials, BaTiO 3 [5][6][7][8][9], (Bi,Na)TiO 3 [10][11][12][13][14][15][16][17][18][19][20][21], (K,Na)NbO 3 [22][23][24][25][26][27][28][29][30][31][32], and their solid-solution systems have been reported.…”