Importance of the crystalline symmetry in the piezoelectric properties of (K0.44+xNa0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3+x/2 lead-free ceramics

TL;DR

This study demonstrates that crystalline symmetry, especially tetragonality, significantly influences the piezoelectric properties of lead-free ceramics, with higher tetragonality correlating with improved electrical responses.

Contribution

It reveals the critical role of crystalline symmetry in determining piezoelectric performance in lead-free ceramics, highlighting the importance of tetragonality and phase composition.

Findings

Higher tetragonality correlates with increased piezoelectric response.

Reduced relaxor behavior is associated with increased tetragonality.

Ceramics with c/a = 1.011 show enhanced electrical properties.

Abstract

Lead-free ceramics (K0.44+xNa0.52Li0.04)(Nb0.86Ta0.10Sb0.04)O3+x/2 (x=-0,06) were prepared by conventional solid state sintering. The results indicate a correlation between crystalline symmetry and electrical properties. Higher tetragonality was observed in samples with higher piezoelectric response. As the tetragonality increase the presence of polymorphic phase decrease associated with a reduction of the relaxor behaviour response. The ceramics with c/a = 1.011 ratio exhibit enhanced electrical properties. The Raman spectroscopy showed a certain asymmetry in the paraelectric phase above the Curie temperature Tc that provokes retention of the polarization. The crystalline symmetry plays a crucial role in the piezoelectric properties of the system.