Modulating Magnetic/Dielectric Loss of Fe-Based Core-Shell Microspheres by Controlling Tetrabutyl Titanate Dosage for...

Area of Science:

• Materials Science
• Nanotechnology
• Electromagnetics

Background:

• Optimizing microwave absorption requires careful control of electromagnetic loss mechanisms in materials.
• Magnetic core-dielectric shell composites offer tunable properties for effective microwave absorption.

Purpose of the Study:

• To investigate the phase evolution of Fe3O4@TiO2 during hydrogen reduction.
• To correlate phase composition and microstructure with microwave absorption properties.
• To enhance microwave absorption performance by optimizing TiO2 shell content.

Main Methods:

• Synthesis of Fe3O4@TiO2 core-shell precursors.
• High-temperature hydrogen reduction to form Fe-based composites (FTR).
• Regulation of TiO2 shell content using tetrabutyl titanate (TBOT) dosage.
• Characterization of phase composition, microstructure, and magnetic properties.
• Evaluation of microwave absorption performance.

Main Results:

• Phase composition evolved from Fe/Fe2O3@TiO2 to Fe@TiO2 and Fe@FeTiO3/TiO2 with increasing TBOT dosage.
• FTR-2.5 exhibited the highest Fe content (86.24 wt%) and saturation magnetization (141.7 emu·g-1).
• Microwave absorption was dominated by magnetic loss in FTR-2.5 and dielectric loss in other composites.
• Enhanced polarization loss (interfacial and dipole) was observed.
• FTR-2.5 achieved a maximum effective absorption bandwidth of 5.92 GHz at 1.95 mm thickness.

Conclusions:

• Phase engineering via controlled hydrogen reduction is effective for tuning microwave absorption.
• The Fe@TiO2 composite (FTR-2.5) demonstrated excellent broadband microwave absorption capabilities.
• This study provides insights into phase evolution and a reference for designing advanced microwave absorbers.