Axial oxygen vacancy-regulated microwave absorption in micron-sized tetragonal BaTiO3 particles

Kyungnae Baek, Seung Yong Lee, Sang Gil Doh, Miyoung Kim, Jerome K. Hyun

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26 Scopus citations


Ferroelectric micro and nanostructures have recently emerged as potential candidates for managing microwave absorption in the GHz range. While various loss mechanisms accounting for the high absorption have been proposed, the contribution of energetically stable axial oxygen vacancies in tetragonal lattices has not been definitively addressed for such structures. In this study, we explore the modulation of microwave absorption in micron-sized BaTiO3 particles through the incorporation of such oxygen vacancies while controlling for differences in particle size, grain size and crystalline phase. Raman, electron paramagnetic resonance (EPR) and electron energy loss spectroscopy (EELS) analysis were used to identify axial oxygen vacancy complexes in BaTiO3 particles of varying degrees of oxygen-deficiency. Measurements of the complex permittivity and permeability for BaTiO3 particles/polyurethane composites across the range from 1 to 18 GHz showed behavior dominated by dielectric relaxation, and a 35% enhancement in dielectric loss for a ∼15 fold increase in oxygen vacancy concentration, attributed to slowing of domain wall movement. An improvement in maximum reflection loss values from −16.9 dB to −43.2 dB was also demonstrated through the incorporation of oxygen vacancies in the particles. Such results suggest that control over the oxygen vacancy concentration can be used as an effective means for freely tuning the microwave absorption in the technologically relevant S, C, and X bands.

Original languageEnglish
Pages (from-to)9749-9755
Number of pages7
JournalJournal of Materials Chemistry C
Issue number36
StatePublished - 2018

Bibliographical note

Funding Information:
This research was supported by the Ministry of Trade, Industry & Energy (MOTIE, Korea) under Industrial Technology Innovation Program No. (10063274, Development and application of multifunctional hybrid composites simultaneously exhibiting Electromagnetic Shielding of 60 dB, Absorption of 85% and Thermal conductivity of 5 W mK−1 at 1.5 GHz) and the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No. NRF-2017R1A5A1015365). STEM-EELS experiments were performed with the ARM-200CF TEM instrument installed at the National Center for Inter-University Research Facilities in Seoul National University. The authors would also like to thank the Korean Basic Science Institute (KBSI) at the Western Seoul center for EPR measurements.

Publisher Copyright:
© The Royal Society of Chemistry.


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