Grain Size Effects in Mn-Modified 0.67BiFeO₃-0.33BaTiO₃ Ceramics

Area of Science:

• Materials Science
• Solid State Physics
• Ceramics Engineering

Background:

• Grain size is a critical factor influencing electroceramic properties for dielectric, piezoelectric, and ferroelectric applications.
• Lead-free piezoelectric ceramics are highly sought after for their environmental benefits and performance.

Purpose of the Study:

• To systematically investigate the effect of grain size on the structure and properties of Mn-modified 0.67BiFeO3-0.33BaTiO3 ceramics.
• To understand the relationship between grain size, phase structure, and functional properties in this lead-free piezoelectric system.

Main Methods:

• Ceramics with average grain sizes from 0.46 to 6.85 μm were fabricated using conventional and spark plasma sintering.
• Structural and property characterizations were performed to analyze the influence of varying grain sizes.

Main Results:

• Increasing grain size shifted the freezing temperature higher, while Burns temperature remained constant.
• Fine-grained ceramics exhibited pronounced relaxor behavior and strong grain size dependency in properties.
• A critical grain size of 2.83 μm maximized dielectric permittivity and plateaued the piezoelectric coefficient in coarse-grained ceramics.

Conclusions:

• Grain size critically influences the dielectric, piezoelectric, and ferroelectric properties of Mn-modified BiFeO3-BaTiO3 ceramics.
• The optimal grain size of 2.83 μm balances contributions from polar nanoregions and domain wall density for enhanced performance.
• These findings provide insights for tailoring lead-free piezoelectric ceramics for advanced applications.