STUDIES ON ORIENTED DOMAIN POLYSTYRENE-TGS COMPOSITE FILMS

1995 ◽  
Vol 09 (17) ◽  
pp. 1039-1044
Author(s):  
S.C. MATHUR ◽  
D.S. RAWAT ◽  
H.O. YADAV ◽  
D.C. DUBE ◽  
A.S. BHALLA
Keyword(s):  
Dielectric Constant ◽  
Transition Temperature ◽  
Dielectric Properties ◽  
Domain Structure ◽  
Spontaneous Polarization ◽  
Coercive Field ◽  
Composite Films ◽  
Microwave Frequency ◽  
Ferroelectric Films ◽  
Microwave Frequencies

Polymer ferroelectric films were prepared by dispersing TGS powder in polystyrene. Permittivity versus temperature plots exhibit a peak at around the transition temperature of TGS. The peak gets suppressed with increasing frequency and the trend continues up to microwave frequencies. We observed that the dielectric constant of films at microwave frequency stays close to the dielectric constant of polystyrene. The domain structure of TGS crystals essentially seems to affect their dielectric properties. Single domain films exhibit a higher spontaneous polarization and a higher coercive field.

The Microstructure and Dielectric Properties of SrTiO3 Modified 0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3 Ceramics

2011 ◽  
Vol 687 ◽  
pp. 433-438
Author(s):  
Jing Song Liu ◽  
Tao Li ◽  
Hui Qin Li ◽  
You Chao Xu ◽  
Ji Qiang Yu
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Transition Temperature ◽  
Dielectric Properties ◽  
Spontaneous Polarization ◽  
Relaxor Behavior ◽  
Maximum Dielectric Constant ◽  
Lower Temperature ◽  
Region Size ◽  
Maximum Permittivity

The microstructure and dielectric properties of ferroelectric solutions which is formulated with (1-x)[0.9Pb(Mg1/3Nb2/3)O3-0.1PbTiO3]-x mol% SrTiO3(x=0, 1, 3 and 5) have been investigated. The ceramics was fabricated by a modified columbite route sintered at 1200 °C. The effects of dopants on microstructure, maximum dielectric constant (εm) and diffuseness of the phase transition, etc. have been studied. It is found that the maximum permittivity (εm) increases to 24968 for the ST-doped (1 mol %) sample, subsequently decreases with ST addition and its corresponding phase-transition-temperature (Tm) shifts to the lower temperature. The variation of εmis caused by the decrease of polar nano-region size, increase of the fluctuation of the component and the increase of the effective spontaneous polarization. The enhancement of relaxor behavior in the PMN-PT sample is explained by the decrease of FE/AFE coupling.

scholarly journals Crystallization and Dielectric Properties of MWCNT /Poly(1-Butene) Composite Films by a Solution Casting Method

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 755
Author(s):  
Lingfei Li ◽  
Qiu Sun ◽  
Xiangqun Chen ◽  
Yongjun Xu ◽  
Zhaohua Jiang
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Breakdown Strength ◽  
Composite Films ◽  
Conductive Filler ◽  
Interfacial Polarization ◽  
Solution Casting ◽  
Casting Method ◽  
Solution Casting Method

In this work, poly(1-butene) (PB-1) composite films with multi-walled carbon nanotubes (MWCNT) were prepared by a solution casting method. The relationship between the dielectric properties and the crystal transformation process of the films was investigated. It was indicated that there were two crystal forms of I and II of PB-1 during the solution crystallization process. With the prolongation of the phase transition time, form II was converted into form I. The addition of the conductive filler (MWCNT) accelerated the rate of phase transformation and changed the nucleation mode of PB-1. The presence of crystal form I in the system increased the breakdown strength and the dielectric constant of the films and reduced the dielectric loss, with better stability. In addition, the dielectric constant and the dielectric loss of the MWCNT/PB-1 composite films increased with the addition of MWCNT, due to the interfacial polarization between MWCNT and PB-1 matrix. When the mass fraction of the MWCNT was 1.0%, the composite film had a dielectric constant of 43.9 at 25 °C and 103 Hz, which was 20 times that of the original film.

DIELECTRIC PROPERTIES OF POLY (VINYLIDENE FLUORIDE)/BARIUM TITANATE NANOCOMPOSITES UNDER GAMMA IRRADIATION

2019 ◽  
Vol 184 (3-4) ◽  
pp. 342-346
Author(s):  
K Waree ◽  
K Pangza ◽  
N Jangsawang ◽  
P Thongbai ◽  
S Buranurak
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Gamma Irradiation ◽  
Nanocomposite Film ◽  
Gamma Ray ◽  
Vinylidene Fluoride ◽  
Volume Fraction ◽  
Composite Films ◽  
Significant Difference ◽  
Accumulated Dose

Abstract The main focus of this study is to investigate the effect of gamma irradiation on the electrical properties of PVDF/BT nanocomposites. A 1.25 MeV gamma-ray was delivered to the composite films with different BaTiO3-volume fraction, ƒBT = 0–0.4, and with different absorbed doses ranged 50–2500 Gy. Dielectric properties of PVDF/BaTiO3 composites under frequencies ranged from 100 Hz to 10 MHz at room temperature were investigated using an impedance analyser. An increase of 28% in the dielectric constant and a decrease of 15% in the loss tangent were observed in the PVDF/BT 40 vol% nanocomposite film under the accumulated dose of 1500 Gy. Scanning electron microscopy provided no significant difference in microscopic structures between non-exposed and gamma-exposed materials. Fourier-transform infra-red spectroscopy provides gamma-induced transition of PVDF-crystalline forms as alpha-PVDF into beta-PVDF/gamma-PVDF which has been reported as one of the main factors affected the change of dielectric constant in polymers. UV–visible spectrophotometry has been observed gamma-induced red shift in the absorption edge of the PVDF/BT 40 vol% nanocomposite film from 400 nm to 420 nm under the accumulated dose of 1500 Gy. However, a blue shift is observed with increase the accumulated dose up to 2000 Gy.

Dielectric Properties of CCTO/PVDF Composite Films

2013 ◽  
Vol 816-817 ◽  
pp. 276-279 ◽  
Author(s):  
Fang Fang Wang ◽  
Ya Jun Wang ◽  
Zhi Bo Ren
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Composite Films ◽  
Solution Casting ◽  
Casting Method ◽  
Impedance Analyzer ◽  
Composite Models ◽  
Solution Casting Method ◽  
Pvdf Matrix ◽  
Ccto Powder

To meet the requirement of microelectronic industry, ceramic/polymer composite films made of CaCu3Ti4O12(CCTO) powder as filler and PVDF copolymer as matrix were prepared by solution casting method. The dielectric properties (DP) and morphology of the films were studied by impedance analyzer and scanning electron microscope (SEM) respectively. The dielectric constant could reach 23.96 and loss 0.1082 when mass fraction of CCTO is 50% at 100 Hz. SEM results show that CCTO particles dispersed well in the PVDF matrix. At last, three composite models were used to predict the dielectric constant of the composite films and it is proved that Yamada model fits the experimental data well.

Bismaleimide/Allylnadic-Imide Blends Yield Low Dielectric Constant And Low Water Uptake

1991 ◽  
Vol 227 ◽  
Author(s):  
J-PH Ansermet ◽  
A. Kramer
Keyword(s):  
Dielectric Constant ◽  
Glass Transition ◽  
Transition Temperature ◽  
Dielectric Properties ◽  
Water Uptake ◽  
Water Saturation ◽  
Low Dielectric Constant ◽  
Aliphatic Chain ◽  
Bismaleimide Resin ◽  
Low Dielectric

ABSTRACTThe bismaleimide resin Matrimid 5292A (I) was cocured with an allylnadic-imide resin (EP 433) which contained a long aliphatic chain as backbone (II). Water uptake, swelling, and the dielectric properties (up to 300 MHz) were studied in cast plates. The dielectric constant varied from 5.4 in (I) to 3.2 in (II) at water saturation, compared to 3.1 in (I) to 2.7 in (II) in the dry state. The glass transition temperature stayed above 200 °C at less than 80 mol% of (II).

Study of Ac Conductivity and Dielectric Properties of PMMA with Fe2O3+ Al2O3 Composite Films

2013 ◽  
Vol 209 ◽  
pp. 14-17
Author(s):  
Basavaraja Sannakki ◽  
Anita Gandhe ◽  
V.H. Doddamani
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Loss ◽  
Polymer Composite ◽  
Composite Films ◽  
Weight Percent ◽  
X Ray ◽  
Morphological Studies ◽  
Tan Δ ◽  
Al2o3 Films

Abstract. The PMMA with Fe2O3+ Al2O3 films at different weight percent have been used for measurement of dielectric properties such as dielectric constant, dielectric loss and a. c. conductivity as a function of frequency over the range 50 Hz – 5 MHz at room temperature. The dielectric constant and the dielectric loss (tan δ) of the polymer composite films decreases exponentially at lower frequencies over the range 100 Hz-1 kHz, where as above 1 kHz the values of dielectric constant remains same. But, it has been observed that the value of dielectric constant of PMMA composite films with Fe2O3+ Al2O3 increases as weight percent of Fe2O3+ Al2O3 increases. The a c conductivity of the polymer composite films remains constant over the frequency range 50 Hz to 300 K Hz and afterwards it increases exponentially. Further, PMMA with Fe2O3+ Al2O3 have been characterized using X-Ray diffractometer for the crystallinity. The morphological studies have been made using the FESEM.

scholarly journals Dielectric studies and microwave emissivity of alkaline soil of Alwar with mixing of gypsum

2010 ◽  
Vol 7 (2) ◽  
pp. 519-524
Author(s):  
V. K. Gupta ◽  
R. A. Jangid ◽  
Seema Yadav
Keyword(s):  
Dielectric Constant ◽  
Soil Moisture ◽  
Dielectric Properties ◽  
Soil Moisture Content ◽  
Microwave Frequency ◽  
Alkaline Soil ◽  
Dielectric Studies ◽  
Horizontal Polarization ◽  
Microwave Emissivity ◽  
Percentage Concentration

The real and imaginary parts of dielectric constant (ε' and ε") of alkaline soil of Alwar with mixing of gypsum (0.0% to 10.0%, gravimetrically) determined at 34.50C temperature and at a single microwave frequency 9.78 GHz by wave guide cell method. Mixture of soil and gypsum is prepared at various moistness of soil varying from 0.0% to 12.0%. The ε' and ε" of gypsum are also determined. It was observed that ε' and ε" increases as percentage concentration of gypsum in the soil increase. It was observed that the effect of gypsum mixing on dielectric properties is more significant at higher level of soil moisture content. Further, microwave emissivities are estimated from measured values of ε' and ε" for dry and wet mixture of, soil and gypsum at various observation angles (00-800) for horizontal polarization. It was observed that emissivity of soil decreases as the percentage concentration of gypsum in the soil increases.

scholarly journals Effect of BaTiO3 on the Properties of PVC-Based Composite Thick Films

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5430
Author(s):  
Sarir Uddin ◽  
Naheed Akhtar ◽  
Sumbal Bibi ◽  
Abid Zaman ◽  
Asad Ali ◽  
...  
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
Dielectric Material ◽  
Thick Films ◽  
Ceramic Powder ◽  
Composite Films ◽  
Frequency Dispersion ◽  
Solution Casting Method ◽  
Constant Versus ◽  
Two Phases

Flexible PVC/BT (Polyvinyl chloride/Barium Titanate) composite thick films with (0–30%) volume fractions of BaTiO3 were fabricated via the solution casting method. The effects of BaTiO3 filler on the phase, microstructure and dielectric properties of composite films were investigated. The XRD results revealed that BT particles are embedded in the PVC matrix with no chemical reaction taking place between the two phases. It was observed that the glass transition temperature of PVC had increased with the addition of BT. The frequency dispersion in the dielectric constant versus temperature curves indicated the relaxor nature of the composites. The dielectric constant (εr) measured at 40 °C, increased from 7.6 for pure PVC to 16.1 for 30% of BaTiO3 content in PVC polymer matrix. It is suggested that BaTiO3 ceramic powder enhanced the dielectric properties of PVC and may be used as a flexible dielectric material.

Formation of Ultra Smooth Bi-Based Ferroelectric Films and their size effect on Dielectric Constant

1997 ◽  
Vol 493 ◽  
Author(s):  
H. Tabata ◽  
T. Yanagita ◽  
M. Hamada ◽  
T. Kawai
Keyword(s):  
Thin Films ◽  
Dielectric Constant ◽  
Coercive Field ◽  
Smooth Surface ◽  
Remanent Polarization ◽  
Pulsed Laser ◽  
Laser Deposition ◽  
Gate Bias ◽  
Deposition Technique ◽  
Ferroelectric Films

ABSTACTWe have formed Bi-based ferroelectric films, such as Bi2WO6, Bi2VO5.5(n=1), Bi2SrTa2O9, Bi3TiNbO9(n=2) and Bi4Ti3O12(n=3) using a pulsed laser deposition technique. Especially, the Bi2VO5.5 film shows an atomically smooth surface with a flat 2000-3000Å wide terrace and steps of 8 Å and 16Å which correspond to a half and one unit cell, respectively. The dielectric constant, remanent polarization and coercive field of the Bi2VO5.5 thin films formed on Nb-SrTiO3(100) are 8, 3.0 μ C/cm2 and 16.0 kV/cm, respectively. The Bi2VO5.5 film formed on SiO2/Si(100) shows memory windows of 0.35V against a±2V gate bias during C-V measurements‥

Sintered compacts of nano and micron-sized BaTiO3: Dramatic influence on the microstructure and dielectric properties

2006 ◽  
Vol 21 (4) ◽  
pp. 816-822 ◽  
Author(s):  
Vishnu Shanker ◽  
Tokeer Ahmad ◽  
Henry Ip ◽  
Ashok K. Ganguli
Keyword(s):  
Differential Scanning Calorimetry ◽  
Dielectric Constant ◽  
Transition Temperature ◽  
Dielectric Properties ◽  
High Dielectric Constant ◽  
Scanning Calorimetry ◽  
Ferroelectric Transition ◽  
Maximum Dielectric Constant ◽  
High Dielectric ◽  
First Time

Sintered compacts of nano-sized and micron-sized BaTiO3 show sharp ferroelectric transition and high dielectric constant at specific compositions. The sintered compacts with 1 wt% nano-BaTiO3 show a maximum dielectric constant of 1680. At the transition temperature (Tc) there are two maxima at 0.5 and 2 wt%. The variation in the dielectric constant at Tc is also reflected in the behavior of the ferroelectric transition as studied by differential scanning calorimetry. This interesting oscillatory variation of the dielectric constant and dielectric loss with increase in the amount of nanoparticles in the sintered compacts is observed for the first time. The variation of the dielectric properties and the ferroelectric transition of the sintered compacts could be related to subtle changes in the microstructure.

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