Extraction of Preisach model parameters for fluorite-structure ferroelectrics and antiferroelectrics

Flourite-structure ferroelectrics (FEs) and antiferroelectrics (AFEs) such as HfO2 and its variants have gained copious attention from the semiconductor community, because they enable complementary metal-oxide-semiconductor (CMOS)-compatible platforms for high-density, high-performance non-volatile and volatile memory technologies. While many individual experiments have been conducted to characterize and understand fluorite-structure FEs and AFEs, there has been little effort to aggregate the information needed to benchmark and provide insights into their properties. We present a fast and robust modeling framework that automatically fits the Preisach model to the experimental polarization ($$Q_{FE}$$ Q FE ) versus electric field ($$E_{FE}$$ E FE ) hysteresis characterizations of fluorite-structure FEs. The modifications to the original Preisach model allow the double hysteresis loops in fluorite-structure antiferroelectrics to be captured as well. By fitting the measured data reported in the literature, we observe that ferroelectric polarization and dielectric constant decrease as the coercive field rises in general.

Extraction of Preisach Model Parameters for Fluorite-Structure Ferroelectrics and Antiferroelectrics

Flourite-structure ferroelectrics (FEs) and antiferroelectrics (AFEs) such as HfO2 and its variants have gained copious attentionfrom the semiconductor community, because they enable complementary metal-oxide-semiconductor (CMOS)-compatible platforms for high-density, high-performance non-volatile and volatile memory technologies. While many individual experiments have been conducted to characterize and understand fluorite-structure FEs and AFEs, there has been little effort to aggregatethe information needed to benchmark and provide insights into their properties. We present a fast and robust modeling framework that automatically fits the Preisach model to the experimental polarization (QFE) vs. electric field (EFE) hysteresis characterizations of fluorite-structure FEs. The modifications to the original Preisach model allow the double hysteresis loops influorite-structure antiferroelectrics to be captured as well. By fitting the measured data reported in the literature, we observe that ferroelectric polarization and dielectric constant decrease as the coercive field rises in general.

Effect of Zn on Dielectric Properties of Co-ZnFe2O4 Magnetic Nanoparticles

Dielectric properties of Zn substituted cobalt ferrite (Co1-xZnxFe2O4) magnetic nanoparticles with various Zn concentrations (x = 0.2-0.8) have been successfully investigated. The structure of the prepared samples Co1-xZnxFe2O4 confirmed to be cubic spinel structure using X-ray diffraction analysis. The crystallite size of the sample was found to decrease with the increase of zinc content from 11.6 nm to 9.8 nm, while the lattice parameters found to increase with the increase of zinc from 8.18 to 8.25 Å. For Zinc x = 0.6 at frequency 5 kHz have the highest real dielectric constant (ɛ') was 678.8 and imaginary dielectric constant (ɛ'') was 833.3. The maximum impedance found at zinc x = 0.3 was 138.5. The dielectric constant decrease rapidly with increasing the frequency and then reaches the constant value where the frequency was used from 5-120 kHz.

Investigate Salts type and concentration on the conductivity of Polymer Electrolyte

Polymer electrolytes systems compose of (PEO+KI+I2) and (PEO+RbI+I2) with different concentration, and a fixed amount of ethylene carbonate (EC) and propylene carbonate (PC) over temperatures range 293-343 K prepared by solution cast method. The conductivity and dielectric constant of the gel electrolytes were studied. The conductivity of the electrolytes Ss & Hs increases steadily with increased concentration of salt KI and RbI. The higher value of conductivity of (4.7 10-3 @ RT S.cm-1) for S5 electrolyte which contains (KI 50%). Whereas the maximum amount of conductivity of (5.4 10³ @RT S.cm⁻ˡ) for H5 electrolyte which contains (RbI 50%) the ionic conductivity depends on the ionic radii of the migrating species (cation K⁺, Rb⁺) effect on it. As the temperature increase, the number of free ions also increases, thus increases the diffusion of ions through their free volume of the polymer. The dielectric constant decrease at higher frequencies due to the inability of dipoles to align quickly with the change of applied field. The dielectric constant proportional positively with variation temperature causes an increase in the dielectric constant. The higher the value of (εr), the better is the electrical conductivity.

Влияние электронного облучения на диэлектрические характеристики монокристаллов AgGaSe-=SUB=-2-=/SUB=-

The effect of various doses of electron irradiation on the dielectric constant and electrical conductivity of triple nonlinear AgGaSe2 crystals at different measuring field frequencies in the temperature range of 100-300 K has been investigated. It has been found that single-crystal irradiation leads to a dielectric constant decrease and an electrical conductivity significant increase. It is shown that the dielectric constant and electrical conductivity increase with an temperature increase. It has been established that AgGaSe2 crystals are characterized by the presence of several conductivity types. A significant frequency dispersion of the dielectric properties of the investigated crystals was found.

Fabrication of New Nanocomposites (PMMA-SPO-PS-TiC) and Studying Their Structural and Electrical Properties for Humidity Sensors

Samples have been prepared by adding Titanium carbide nanoparticles to the Poly (methyl methacrylate) and Ethylene-alpha olefin co-polymer (SPO) and Polystyrene (PS) with different weight percentages (o, 2, 4, 6 and 8) wt%. The FTIR analysis, electrical, dielectric, and structural properties have been studied.The dielectric loss and The dielectric constant decrease with increasing of Titanium carbide (TiC) nanoparticles. The A.C electrical conductivity increases with increasing of Titanium carbide (TiC) concentrations and frequency. The D.C electrical conductivity increases with increasing of Titanium carbide (TiC) concentration and temperature. The Activation energy decreases with increasing of Titanium carbide (TiC) nanoparticles. The Humidity sensor application showed that the electrical resistance of (PMMA-SPO-PS-TiC) nanocomposites decreases with increase the Humidity.

Structural and electrical characterization of La3+ substituted PMS-PZT (Zr/Ti:60/40) ceramics

Pb(1-x)Lax [(Zr0.6Ti0.4)(1-x)(Mn1/3Sb2/3)x]O3 ceramics with x = 0.02, 0.03, 0.04, and 0.05 were synthesized by using a conventional solid state reaction route. The influence of La, Mn, and Sb contents on phase structure, microstructure, and electric properties were investigated. The results of X-ray diffraction (XRD) show that the phase structure of the ceramics transforms from rhombohedral phase to tetragonal phase. However, the minority pyrochlore phase appears on the micrographs of XRD and SEM if the doping concentration is greater than 2 mol%. The grain size of the ceramics gradually increases (from 1.36 μm to 1.57 μm) with increasing doping. The dielectric properties of the ceramics have been measured as a function of temperature in the range of 20 °C to 430 °C at 1 kHz. The results indicate that the transition temperature and the maximum dielectric constant decrease with increasing PL-PMS content in the system. These results clearly show the significance of PL-PMS in controlling the dielectric behavior of the PL-PMS-PZT system.

Reduction of dielectric constant of LTCC substrates by introduction of controlled porosity

Purpose This paper aims to present a method for the reduction of dielectric constant of low-temperature co-fired ceramics (LTCC) substrates with the use of controlled internal porosity. Design/methodology/approach A glass-ceramic green tape with addition of graphite as a pore former was developed. The green tapes were laminated and then sintered into multilayer structures with porous interior and thin external dense layers. Microstructure of green and fired structures was studied using optical and scanning microscopy. The behavior of the samples during heating was examined in a heating microscope. Impedance spectroscopy was applied for investigation of dielectric properties of the fabricated substrates. Findings Microstructure and dielectric properties of the fabricated LTCC structures were compared with the characteristics for non-porous samples with the similar composition. Introduction of 50 Wt.% admixture of graphite in the internal layers of the LTCC substrate was found to result in decrease in dielectric constant value down to about 3. Application of non-porous outer layers improved mechanical strength of the structure and smoothness of its surface, allowing screen printing of conductive pastes on both sides of the substrate. Practical implications The rapid growth of the wireless communication industry has created a great demand for the development of new and improved materials and devices operating properly at high frequencies. The fabricated materials can be useful for substrates of microwave devices. Originality/value The paper presents an innovative method of dielectric constant decrease of substrate materials. Getting insight into the phenomena responsible for formation of pores is crucial for designing materials for microwave electronics.

Dielectric Properties of CaTiO3 Doped Ba0.65Sr0.35TiO3 (BST) AC High Voltage Capacitor Ceramics

The dielectric properties of (1-x) Ba0.65Sr0.35TiO3-xCaTiO3(x=0, 0.03, 0.06, 0.10, 0.15) ceramics were investigated. XRD analysis shows that CaTiO3doping can be fully incorporated into the perovskite lattice of BST except increasing peak intensity. The experimental result shows that doping a certain amount of CaTiO3could form fine crystal grain structure, enhance the density, and enhance Ac withstand voltage strength, increase dielectric constant and decrease the dielectric loss. While doping excessive CaTiO3could make the geometrical distortion, increase the porosity and grain size, develop the internal stresses and finally lead to the dielectric constant decrease. The BSTC ceramics sintered at 1350 °C for 2 h with 6 mol.% CaTiO3doping has the best properties, εrof 3862, tanδ of 0.046, Ebof 5 kV/mm (AC), the value of C/C ranges is-26.7%~-66.2% in-50 °C ~ 100 °C temperature range.

Refractive Index Dispersion and Optical Dielectric Properties of Poly(N-Carbazole)/Poly(vinylpyrrolidone) Blends

Different compositions of blended poly (N-carbazole) (PVK) with polyvinylpyrrolidone (PVP) were prepared. The optical properties such as infinite frequency refractive index (n∞), average oscillator wavelength (λ0), oscillator strength (So), dispersion energy (Ed), oscillator energy (Eo) and optical dielectric loss have been calculated. The refractive index of polymer blending systems significantly changes with the volume composition of PVP and shows a normal dispersion behavior. Mean while, the values of n∞, Edand Eoincrease with the increase of PVP composition. Both of the real and imaginary part of the dielectric constant decrease as the wavelength increase. Thus, it reveals that the polymer composition has influenced the optical properties of the polymer blending system.