Induced core–shell structure and the electric properties of (K0.48Na0.52)0.95Li0.05Nb0.95Sb0.05O3 ceramics

Abstract

The relationship among dielectric anomaly, ferroelectric response, defects, and microstructures was established for (K_0.48(1+x)Na_0.52)_0.95Li_0.05Nb_0.95Sb_0.05O₃ (x = 0.04, 0.00, −0.02, −0.04 and −0.08) ceramics. For x = −0.02 and −0.04, larger coercive fields and lower remnant polarizations were obtained; besides, an additional dielectric relaxation behavior was observed with the activation energy E_a being about 2.19 eV and 1.92 eV, respectively. Furthermore, the grain and grain boundary contributions to the capacitance were separated using impedance spectroscopy, which, combined with back-scattering characterization, firmly indicates the core–shell structure of K-deficient samples (x = −0.02 and −0.04). Unlike the cores, the shells possess a large amount of K⁺ vacancies (). This work paves a way for regulating the fine structure and more on the electrical properties of KNN-based materials.