Induced core–shell structure and the electric properties of (K_0.48Na_0.52)_0.95Li_0.05Nb_0.95Sb_0.05O₃ ceramics

Abstract

The relationship among dielectric anomaly, ferroelectric response, defects, and microstructures was established for (KNa)LiNbSbO (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 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.

Influence of oxygen vacancies on core‐shell formation in solid solutions of (Na,Bi)TiO3 and SrTiO3

“…Chemical heterogeneity in the form of core-shell structures can develop in lead-free (Na 1/2 Bi 1/2 )TiO 3 (NBT)-based and (K 0.5 Na 0.5 )NbO 3 (KNN)-based ceramics during a regular solid-state sintering process. 1,2,3,4,5,6 These can have a high impact on electric and ferroelectric properties. Even in pure KNN, core-shell material can form depending on the type of Nb-oxide used as an educt.…”

Thermally-induced phase transformations in KNNS-BNKZ lead-free piezoceramics

“…Similarly, Xing [39] also found a sudden decrease of grain size in that the amount of K in the core is slightly higher than that of Na, but lower in the shell, as shown in Figure 2(a). Similarly, Zhou [43]…”