Local disorder in Na_0.5Bi_0.5TiO₃-piezoceramic determined by 3D electron diffuse scattering

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Local structural distortions are key to piezoelectric properties in Na$_{0.5}$Bi$_{0.5}$TiO$_{3}$ (NBT)-based solid solutions.
• Understanding these distortions is crucial for tuning piezoelectric performance near the morphotropic phase boundary.

Purpose of the Study:

• To map local structural disorders in a lead-free ternary system: 85%NBT-10%Bi$_{0.5}$K$_{0.5}$TiO$_{3}$-5%BaTiO$_{3}$.
• To develop a comprehensive model explaining diffuse scattering features related to these disorders.

Main Methods:

• Utilized 3D electron diffraction to analyze local structural disorders in reciprocal space.
• Analyzed the intensity and morphology of weak diffuse scattering to build a disorder model.

Main Results:

• Identified plate-like, in-phase oxygen octahedral nanoscale domains within an antiphase tilted matrix.
• Observed contributions from A-site chemical short-range order (Na/Bi) and polar displacements to diffuse scattering.

Conclusions:

• The developed model successfully explains all observed diffraction features.
• Provides insights into the nature of local structural distortions in NBT-based solid solutions, addressing existing controversies.