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)NbO3–BaZrO3–(La,Na)TiO3 ternary ceramic system. The specimens were synthesized by a conventional solid-state 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(K0.45Na0.5Li0.05)NbO3–0.09BaZrO3–0.0075(La,Na)TiO3 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.

Keywords

• Lead-free piezoceramics
• vertical morphotropic phase boundary
• reducing atmosphere
• high-temperature XRD
• phase transition