Terahertz Characterization of Lead-Free Dielectrics for Different Applications

Abstract

In this spotlight on applications, we describe our recent progress on the terahertz (THz) characterization of linear and nonlinear dielectrics for broadening their applications in different electrical devices. We begin with a discussion on the behavior of dielectrics over a broadband of frequencies and describe the main characteristics of ferroelectrics, as they are an important category of nonlinear dielectrics. We then move on to look at the influence of point defects, porosities, and interfaces, including grain boundaries and domain walls, on the dielectric properties at THz frequencies. Based on our studies on linear dielectrics, we show that THz characterization is able to probe the effect of porosities, point defects, shear planes, and grain boundaries to improve dielectric properties for telecommunication applications. Further, we demonstrate that THz measurements on relaxor ferroelectrics can be successfully used to study the reversibility of the electric field-induced phase transitions, providing guidance for improving their energy storage efficiency in capacitors. Finally, we show that THz characterization can be used to characterize the effect of domain walls in ferroelectrics. In particular, our studies indicate that the dipoles located within domain walls provide a lower contribution to the permittivity at THz frequencies than the dipoles present in domains. The new findings could help develop a new memory device based on nondestructive reading operations using a THz beam.

Chemical-Composition Tuning-Enabled Optimization of Structure, Properties, and Performance of Lead-Free (1 – x)BaZr0.05Ti0.95O3–(x)Ba0.92Ca0.08TiO3 Electroceramics

“…If the grain size is smaller (1.5 μm for x = 0.00) or more (50 μm for x = 1.00), then the piezoelectric coefficient values are observed to be decreasing. Thus, a dense ferroelectric sample with optimum grain size is essential to attain higher value of piezoelectric coefficients. , …”

Achieving high energy density at a low electric field of high-temperature sandwich-structured polymer dielectric composite by PVDF crystallinity regulation

“…It should be noted that these linear dielectric polymers lack spontaneous polarization and perform low dielectric constant. 14 Furthermore, with temperature increasing, their leakage current increase, resulting in a decrease in discharge energy density ( U d ) and charge–discharge efficiency ( η ). The U d of dielectric material is described by the equation: , where D is electric displacement, E is the exerted electric field, the D can be calculated by D = ε 0 ε r E , ε 0 , and ε r represent the permittivity of vacuum and dielectric, respectively.…”

“…It should be noted that these linear dielectric polymers lack spontaneous polarization and perform low dielectric constant. 14 Furthermore, with temperature increasing, their leakage current increase, resulting in a decrease in discharge energy density (U d ) and charge-discharge efficiency (Z). The U d of dielectric material is described by the equation:…”

Near-IR Light-Tunable Omnidirectional Broadband Terahertz Wave Antireflection Based on a PEDOT:PSS/Graphene Hybrid Coating

“…Terahertz (THz) technology has attracted tremendous attention over the years due to the unique properties of THz radiation, , and it has become a great potential tool for a variety of applications, including material characterization, , biomedical imaging, , and wireless communication. , For the implementation of THz technology, − there is a critical need for THz components such as emitters, detectors, polarizers, modulators, filters, and beam splitters. However, these THz components are generally fabricated on substrates with a high optical refractive index, such as silicon, which results in the refractive index mismatch at the interface, therefore giving rise to unwanted reflections.…”

“…Terahertz (THz) technology has attracted tremendous attention over the years due to the unique properties of THz radiation, 1,2 and it has become a great potential tool for a variety of applications, including material characterization, 3,4 biomedical imaging, 5,6 and wireless communication. 7,8 For the implementation of THz technology, 9−11 there is a critical need for THz components such as emitters, detectors, polarizers, modulators, filters, and beam splitters.…”