Novel Core–Shell Nanostructure in Percolative PZN−PZT/Ag Ferroelectric Composites

Abstract

Novel percolative PZN−PZT/Ag ferroelectric composites with intragranular structure were prepared with micro‐PZN−PZT and nano‐Ag particles. The typical core–shell nanostructures were systematically investigated by TEM, in which, the nanoscale shells act as interlayers between the Ag cores and the ceramic matrix. Excellent dielectric properties, such as high dielectric constant (εr ~16600) and low dielectric loss (< 0.056) were reported. The high dielectric constant originates from the coeffect of “microcapacitors” and Maxwell–Wager–Sillars (MWS) polarization. Especially, the core−shell structure may reinforce the MWS effect. Meanwhile, the insulating interlayers reduce the tunnel current between neighboring Ag cores by causing potential barriers, endowing the nanocomposites with low dielectric loss. This approach can be used to realize a novel material with high dielectric constant over a wide frequency and temperature range.

Refreshing doping concept in perovskite piezoceramics: Composite modulation hidden behind lattice substitution

“…This is mainly due to the large difference in conductivity between the ZnO phase and the matrix perovskite phase because the former is a semiconductor while the latter is an insulator. 13,48 Moreover, the interfacial polarization direction with respect to the space charge distribution is oriented by the external electric field, and the stronger the external electric field, the stronger is the built-in electric field generated by the interfacial polarization. Accordingly, it can be determined that under the artificial poling conditions in this experiment (4 kV/mm), the built-in electric field can enhance the degree of domain orientation ( Figure 11G-H), thereby improving the piezoelectric performance.…”

“…Unlike the undoped system, there is a concentrated area of space charge distribution near the heterogeneous interface inside the doped material. This is mainly due to the large difference in conductivity between the ZnO phase and the matrix perovskite phase because the former is a semiconductor while the latter is an insulator 13,48 . Moreover, the interfacial polarization direction with respect to the space charge distribution is oriented by the external electric field, and the stronger the external electric field, the stronger is the built‐in electric field generated by the interfacial polarization.…”