Improvement of electric insulation in dielectric layered perovskite nickelate films via fluorination

2022 ◽  
Author(s):  
Takuma Nishimura ◽  
Tsukasa Katayama ◽  
Shishin Mo ◽  
Akira Chikamatsu ◽  
Tetsuya Hasegawa
Keyword(s):  
Dielectric Permittivity ◽  
Loss Tangent ◽  
Layered Perovskite ◽  
Electric Insulation ◽  
Tan Δ

Layered perovskite nickelates have recently emerged as materials with colossal dielectric permittivity. However, they exhibit relatively high values of loss tangent (tan δ) owing to insufficient electric insulation; thus, lowering...

scholarly journals Investigation on the Microwave Properties of Kenaf and Rice-Husk Fiber Reinforced Pla Composite Utilizing One-Port Coaxial Transmission Line Reflection Method

2011 ◽  
Vol 471-472 ◽  
pp. 868-873 ◽  
Author(s):  
Nor'aini Ahmad Zawawi ◽  
Alyani Ismail ◽  
Abdan Khalina ◽  
Mohd Adzir Mahdi
Keyword(s):  
Dielectric Permittivity ◽  
Rice Husk ◽  
Loss Tangent ◽  
Wide Frequency Range ◽  
Microwave Properties ◽  
Equal Weight ◽  
Frequency Range ◽  
Weight Percentage ◽  
Plastic Composites ◽  
Tan Δ

The paper investigates the microwave properties of natural fiber reinforced biodegradable plastic composites in order to recognize their potential as alternatives to common printed circuit board (PCB) for electronic communication industries. Thus, the paper reports on measured dielectric properties for two new composites under study: Kenaf/Poly Lactic Acid (PLA) and rice husk/PLA and their results are compared. The sample is made from equal weight percentage loading (50%wt - 50%wt) of kenaf and PLA. Another sample has also equal weight percentage loading (50% wt - 50%wt) of rice husk and PLA. The complex dielectric permittivity (ε = ε' – jε'') and loss tangent (tan δ) of the two samples of natural fibers plastic composites have been studied in the frequency range of 500 MHz to 10 GHz. The dielectric permittivity is measured by scattering parameter (S-parameter) using a Vector Network Analyzer (VNA). The concentration dependence of permittivity and loss tangent is analyzed for each sample. It is observed that from 500 MHz to 3.32 GHz, real permittivity (ε') values are consistent throughout the wide frequency range, at approximately 3.3. However, the permittivity seems to decrease at higher frequencies starting from 3.35 GHz for both samples, down to 2.5 at 10 GHz. Measured results show that kenaf/PLA mixture has higher permittivity (ε') than the rice husk/PLA composite across the wide frequency range. Meanwhile, loss tangent (tan δ) is low and remains similar for both types of fiber compositions.

scholarly journals Thermoplastic Polyurethane/Lead Zirconate Titanate/Carbon Nanotube Composites with Very High Dielectric Permittivity and Low Dielectric Loss

2020 ◽  
Vol 4 (3) ◽  
pp. 137
Author(s):  
Gayaneh Petrossian ◽  
Nahal Aliheidari ◽  
Amir Ameli
Keyword(s):  
Dielectric Loss ◽  
Dielectric Permittivity ◽  
Lead Zirconate Titanate ◽  
Thermoplastic Polyurethane ◽  
Lead Zirconate ◽  
Low Dielectric ◽  
High Dielectric Permittivity ◽  
Tan Δ ◽  
High Dielectric ◽  
Very High

Ternary composites of flexible thermoplastic polyurethane (TPU), lead zirconate titanate (PZT), and multiwalled carbon nanotubes (MWCNTs) with very high dielectric permittivity (εr) and low dielectric loss (tan δ) are reported. To assess the evolution of dielectric properties with the interactions between conductive and dielectric fillers, composites were designed with a range of content for PZT (0–30 vol%) and MWCNT (0–1 vol%). The microstructure was composed of PZT-rich and segregated MWCNT-rich regions, which could effectively prevent the formation of macroscopic MWCNT conductive networks and thus reduce the high ohmic loss. Therefore, εr increased by a maximum of tenfold, reaching up to 166 by the addition of up to 1 vol% MWCNT to TPU/PZT. More importantly, tan δ remained relatively unchanged at 0.06–0.08, a similar range to that of pure TPU. εr/tan δ ratio reached 2870 at TPU/30 vol% PZT/0.5 vol% MWCNT, exceeding most of the reported values. This work demonstrates the potential of three-phase polymer/conductive filler/dielectric filler composites for efficient charge storage applications.

scholarly journals Paving the Way to Eco-Friendly IoT Antennas: Tencel-Based Ultra-Thin Compact Monopole and Its Applications to ZigBee

Sensors ◽  
2020 ◽  
Vol 20 (13) ◽  
pp. 3658
Author(s):  
María Elena de Cos Gómez ◽  
Humberto Fernández Álvarez ◽  
Alicia Flórez Berdasco ◽  
Fernando Las-Heras Andrés
Keyword(s):  
Dielectric Permittivity ◽  
Frequency Band ◽  
Loss Tangent ◽  
Relative Dielectric Permittivity ◽  
Iot Applications ◽  
Half Wave ◽  
And Performance ◽  
Dielectric Permittivity And Loss ◽  
Range Test ◽  
The Way

An ultrathin, compact ecofriendly antenna suitable for IoT applications around 2.45 GHz is achieved as a result of exploring the use of Tencel fabric for the antenna’s design. The botanical ecofriendly Tencel is electromagnetically characterized, in terms of relative dielectric permittivity and loss tangent, in the target IoT frequency band. To explore the suitability of the Tencel, a comparison is conducted with conventionally used RO3003, with similar relative dielectric permittivity, regarding the antenna dimensions and performance. In addition, the antenna robustness under bent conditions is also analyzed by measurement. To assess the relevance of this contribution, the ultrathin ecofriendly Tencel-based antenna is compared with recently published antennas for IoT in the same band and also, with commercial half-wave dipole by performing a range test on a ZigBee-based IoT testbed.

Giant dielectric permittivity with low loss tangent and excellent non−Ohmic properties of the (Na+, Sr2+, Y3+)Cu3Ti4O12 ceramic system

2020 ◽  
Vol 46 (7) ◽  
pp. 9780-9785 ◽  
Author(s):  
Pariwat Saengvong ◽  
Jakkree Boonlakhorn ◽  
Narong Chanlek ◽  
Bundit Putasaeng ◽  
Prasit Thongbai
Keyword(s):  
Dielectric Permittivity ◽  
Loss Tangent ◽  
Ceramic System ◽  
Low Loss ◽  
Giant Dielectric

Balanced development of dielectric permittivity, loss tangent, and temperature stability in K0.5Na0.5NbO3-based ceramic capacitors

2020 ◽  
Vol 817 ◽  
pp. 152798 ◽  
Author(s):  
Zhiyong Liu ◽  
An Zhang ◽  
Jinshan Lu ◽  
Bing Xie ◽  
Bingliang Liang ◽  
...  
Keyword(s):  
Dielectric Permittivity ◽  
Loss Tangent ◽  
Temperature Stability ◽  
Balanced Development ◽  
Ceramic Capacitors

Radio-wave reflectivity from cold glaciers

2020 ◽  
Author(s):  
Olga Yushkova ◽  
Taisiya Dymova ◽  
Viktor Popovnin
Keyword(s):  
Dielectric Constant ◽  
Dielectric Permittivity ◽  
Reflection Coefficient ◽  
Surface Temperature ◽  
Frequency Dependence ◽  
Depth Profile ◽  
Loss Tangent ◽  
Thin Layers ◽  
The Arctic ◽  
Radio Waves

<p>Radio echo-sounding is a powerful technique for investigating the subsurface of the glaciers. However, physics underlying the formation of the reflected signal is sometimes oversimplified  in the geophysical glacier studies, leading to wrong results. Various remote sensing techniques use different wavelengths (e.g., 13.575 GHz for CryoSat and 20-25/200-600 MHz for ground-penetrating radar), but it is still not clear which particular wavelengths are the best to detect different characteristics of the ice. Possibly, the results gained using different wavelengths may not coincide but rather complement each other due to frequency dependence of the dielectric permittivity and conductivity of snow, ice and especially water.</p><p>Here we attempt to construct an electrophysical model of a cold glacier. This mathematical model considers the variability of the depth profile of the complex dielectric permittivity depending on the frequency of the probing radio signal and the surface temperature. A series of calculations of the reflection coefficients of radio waves from the modelled glacier show that at low temperatures for frequencies above 1 MHz the real part of the dielectric constant of the glacier does not change with frequency and surface temperature, but depends on the glacier structure, while the depth profile of the loss tangent is constant throughout the glacier.  As wavelength decreases, the absorption of radio-waves by the glacier decreases and the frequency dependence of the reflection coefficient becomes a periodic function, its period and amplitude depend on the glacier thickness, the dielectric constant of the bedrock and ice on the surface.</p><p>The range of radio-waves from 0.1 to 1 MHz is not optimal for sounding cold glaciers: the absorption of radio-waves by ice is large for studying thick layers of the glacier, and the wavelength does not allow studying thin layers. Hence, reflection from the glacier surface prevails upon reflection of the signal. The small absorption of short radio waves by ice leads to the fact that the frequency dependence of the reflection coefficient of short radio-waves is practically the sum of the partial reflections of radio-waves from the surface and internal snow/firn and firn/ice boundaries. Period and amplitude of oscillations of the function  depend on the depth of the internal boundaries and the gradient of dielectric characteristics of ice, snow, firn and bedrock.</p><p>Changes in surface temperature, leading to a change in the loss tangent of the upper glacier layers, are manifested in the phase magnitude of the reflection coefficient of radio-waves:it grows with the temperature. Theoretically, the high-frequency signal reflected from the glacier contains information about the structure of the cold glacier and the depth distribution of the dielectric constant, but to restore the electrophysical parameters of the glaciers, it is necessary to use a broadband signal with smooth spectrum and high digitization speed.</p><p>The reported study was funded by RFBR, project number 18-05-60080 (“Dangerous nival-glacial and cryogenic processes and their impact on infrastructure in the Arctic”).</p>

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