Microstructure and Electrical Properties of Eu-Doped K_0.5Na_0.5NbO₃ Ceramics

Abstract

(K_0.5Na_0.5)1–3xEu_xNbO₃ (0≤x≤0.05) lead-free ceramics have been prepared by a conventional solid state reaction. XRD show that the ceramics possess a pure perovskite structure with orthorhombic symmetry. Dopant Eu restrains the grain growth, decreases the ferroelectric-paraelectric phase transition temperature and leads to a diffuse phase transition. With the increase of Eu, the observed remanent polarization (P_r) decreases while the coercive field (E_c) remains almost unchanged. Nevertheless, for the increase in relative permittivity, the sample with x = 0.005 exhibits the optimum piezoelectric properties, giving a large piezoelectric coefficient (d₃₃ = 121 pC/N) and a high planar electromechanical coupling coefficient (k_p = 0.41).

Keywords:

• Lead-free ceramics
• dielectric
• piezoelectric
• ferroelectric

Funding

This work was financially supported by the Natural Science Foundation of China (Grant No. 51275217).