Dielectric Properties of BaTiO3-Epoxy Nanocomposites in the Microwave Regime.

Hsin-Yu Yao,Tsun-Hsu Chang,Yi-Wen Lin

doi:10.3390/polym13091391

Abstract

We synthesized BaTiO3–epoxy nanocomposites (particle size < 100 nm) with volume fractions up to 25 vol. %, whose high-frequency complex permittivity was characterized from 8.2 to 12.5 GHz. The maximum dielectric constant approaches 9.499 with an acceptable loss tangent of 0.113. The dielectric loss gradually saturates when the particle concentration is higher than 15 vol. %. This special feature is an important key to realizing high-k and low-loss nanocomposites. By comparing the theoretical predictions and the experimental data, four applicable effective-medium models are suggested. The retrieved dielectric constant (loss tangent) of 100-nm BaTiO3 nanopowder is in the range of 50–90 (0.1–0.15) at 8.2–12.5 GHz, exhibiting weak frequency dispersion. Two multilayer microwave devices—total reflection and antireflection coatings—are designed based on the fabricated nanocomposites. Both devices show good performance and allow broadband operation.

Highlights

BaTiO3 –Epoxy Nanocomposites inIn the era of fifth-generation mobile networks, plenty of works have been devoted to developing integrable microwave components, such as microstrip antenna [1], circulators [2], capacitors [3,4,5], filters [6], low-loss waveguides [7], resonators [8] and multifunctional surface coatings [9,10]
BaTiO3 –epoxy (BTEP) composites have been intensively studied and regarded as a potential solution to meet the demand for low loss [31,32]
A maximum dielectric constant of 7.5–8.5 with a low loss tangent of 0.02–0.03 for a 20 vol % BTEP nanocomposite was demonstrated at 8.2–12.5 GHz

Summary

Introduction

In the era of fifth-generation mobile networks, plenty of works have been devoted to developing integrable microwave components, such as microstrip antenna [1], circulators [2], capacitors [3,4,5], filters [6], low-loss waveguides [7], resonators [8] and multifunctional surface coatings [9,10]. Regarding the high-frequency dielectric characterization, Yang et al [30] discovered that the dielectric constants of 40 vol % BTEP samples at 3–18 GHz were, respectively, 11 and 15 when 100 nm and 200 nm nanoparticles were doped. A maximum dielectric constant of 7.5–8.5 with a low loss tangent of 0.02–0.03 for a 20 vol % BTEP nanocomposite was demonstrated at 8.2–12.5 GHz. a high-k and low-loss BTEP nanocomposite has been achieved, there is still no complete investigation of the relationship between the BaTiO3 concentration and the resulting composite’s electric performance at the highfrequency region (>1 GHz). BaTiO3 nanopowder at the high-frequency region and the system’s morphological factor With such information, two proof-of-principle microwave devices are proposed: a total reflection coating and an antireflection coating.

Materials and Methods

Microscale of BaTiO

Microwave Applications of High-k Nanocomposites

Conclusions