RESUMO
The relationship among dielectric anomaly, ferroelectric response, defects, and microstructures was established for (K0.48(1+x)Na0.52)0.95Li0.05Nb0.95Sb0.05O3 (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 Ea 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.
