Dielectric Properties of Pd/Y8Z Composites

1999 ◽  
Vol 575 ◽  
Author(s):  
Mark G.H.M. Hendriks ◽  
Henk Verwei ◽  
Manon P. Timmerman
Keyword(s):  
Dielectric Properties ◽  
Percolation Threshold ◽  
Double Layer ◽  
Low Temperatures ◽  
Room Temperature ◽  
Electronic Conductivity ◽  
Impedance Measurements ◽  
High Frequencies ◽  
A Value ◽  
Double Layer Capacity

ABSTRACTImpedance measurements are performed on Pd/Y8Z composites. At 500 'C a 2- 108 times enhancement of the permittivity of the composite at a Pd composition near the percolation threshold for electronic conductivity relative to Y8Z at room temperature is obtained. At high frequencies, the enhancement decreases to a value comparable to geometric capacity of the composite as the double-layer capacity diminishes. At relatively low temperatures the capacity of Y8Z, due to ionic polarisability, increases with temperature.

NEAR STATIONARY DIELECTRIC PROPERTIES IN HALF-METALLIC FERROMAGNETIC Ag:CrO2 NANOCOMPOSITE PARTICLES AT HIGH FREQUENCIES

2008 ◽  
Vol 22 (14) ◽  
pp. 1423-1429 ◽  
Author(s):  
G. P. SINGH ◽  
S. RAM ◽  
A. K. THAKUR
Keyword(s):  
Dielectric Constant ◽  
Dielectric Properties ◽  
High Frequency ◽  
Power Loss ◽  
Room Temperature ◽  
Half Metallic ◽  
Nanocomposite Particles ◽  
High Frequencies ◽  
A Value ◽  
Ferromagnetic Particles

Nanocomposite particles of silver modified CrO 2 were synthesized by a chemical CrO 3 → CrO 2 reduction in the presence of Ag + in an aqueous medium whereby the half-metallic ferromagnetic particles of CrO 2 are generated within a shell of silver. The dielectric constant εr, AC resistivity ρAC, and the dielectric power loss were studied after annealing recovered Ag:CrO 2 powder (compacted as the billets), at 300°C for 2 h in air, at 10–1000 kHz frequencies (f) at room temperature. At 10 kHz, the ρr has as large a value as 49, with ρ AC = 106 k Ω-cm and power loss 0.42. As f increases, all the three parameters are decreased monotonically to the values 28, 3.6 kΩ-cm, and 0.06 respectively. Almost a steady εr as well as ρAC value exists, with controlled power loss, useful for high frequency applications over f ≥ 400 kHz .

scholarly journals Reference-Electrode Free pH Sensing Using Impedance Spectroscopy

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 742 ◽  
Author(s):  
Laura Folkertsma ◽  
Lennart Gehrenkemper ◽  
Jan Eijkel ◽  
Karin Gerritsen ◽  
Mathieu Odijk
Keyword(s):  
Impedance Spectroscopy ◽  
Double Layer ◽  
Tin Oxide ◽  
Indium Tin Oxide ◽  
Reference Electrode ◽  
Ph Sensing ◽  
Low Frequencies ◽  
High Frequencies ◽  
Double Layer Capacity ◽  
Proof Of Principle

We present a reference-electrode free sensor able to measure both pH and conductivitybased on impedance spectroscopy. The electrode is made of a layer of indium-tin-oxide (ITO). Theimpedance of this electrode at low frequencies depends on its double layer capacity, which varieswith pH due to modification of oxide groups at the ITO surface. At high frequencies, the impedanceis determined by the resistance in the system, which corresponds to the inverse conductivity of thesolution. Because no reference electrode is needed for this technique, miniaturization of the pHsensor is simple. We demonstrate a proof-of-principle experiment of the sensor for human plasmapH measurements.

Strength of Neoprene Compounds and the Effect of Salt Solutions

1983 ◽  
Vol 56 (4) ◽  
pp. 845-852 ◽  
Author(s):  
A. K. Bhowmick ◽  
A. N. Gent
Keyword(s):  
Tensile Strength ◽  
Lower Limit ◽  
Low Temperatures ◽  
Environmental Effect ◽  
Room Temperature ◽  
Characteristic Temperature ◽  
Salt Solutions ◽  
A Value ◽  
Fecl3 Solution ◽  
Tear Propagation

Abstract Soft CR vulcanizates resemble NR vulcanizates in many ways. Their tensile strength is high at low temperatures and drops sharply at a characteristic temperature to a value of about 1–1.5 MPa. Their tear resistance decreases smoothly as the temperature is raised and does not reach a lower limit, even at temperatures as high as 150°C. However, they show continuous tear propagation at room temperature under relatively large tear forces, whereas NR materials do not. This difference must reflect different strengths of the crystallites formed at the tear tip, those in CR being significantly weaker. Also, a specific environmental effect is noted: When immersed in solutions of FeCl3, the CR materials show more rapid tearing, and they tear at significantly lower forces than in water or in NaCl solutions (or in air). Although they swell continuously in water and in salt solutions, the rate of swelling seems far too low to account for the weakening observed. Moreover, the swelling is greater in water, whereas the weakening is specific to FeCl3 solution. It is attributed to a chemical reaction between FeCl3 and the CR molecule.

Differential Capacity of the Double-Layer Formed at a Solid Electrode (Pt, Au)/Ionic Liquid Interface

2007 ◽  
Vol 62 (3-4) ◽  
pp. 187-190 ◽  
Author(s):  
Andrzej Lewandowski ◽  
Maciej Galiński ◽  
Sebastian R. Krajewski
Keyword(s):  
Ionic Liquid ◽  
Ionic Liquids ◽  
Double Layer ◽  
Electrode System ◽  
Liquid Interface ◽  
Potential Range ◽  
Differential Capacity ◽  
Impedance Measurements ◽  
Solid Electrode ◽  
Double Layer Capacity

The differential capacity at the electrode (Pt, Au)/ionic liquid interface of 18 ionic liquids (ILs), was measured applying chronoamperometry. The measurements were done by a two electrode system. The double layer capacity at the Pt/IL and Au/IL interface was 1 - 8 μF/cm2. The capacity, estimated from the impedance measurements, was approximately constant within a potential range of ca. 3 V.

The thermal expansion of alkali halides at low temperatures

1965 ◽  
Vol 286 (1405) ◽  
pp. 204-217 ◽  
Keyword(s):  
Low Temperatures ◽  
Room Temperature ◽  
Alkali Halides ◽  
Theoretical Models ◽  
Liquid Oxygen ◽  
Rock Salt Structure ◽  
General Behaviour ◽  
A Value ◽  
Salt Structure ◽  
Expansion Coefficients

Linear thermal expansions of eight alkali halides have been determined at liquid oxygen temperatures and at temperatures from 30 °K down to 2 °K. For temperatures T ≤ θ/20, where θ is the Debye temperature, the expansion coefficients are well represented by α = AT 3 + BT 5 . Values are reported for the Grüneisen parameter γ = 3α V/Cx , where C/V is the heat capacity per unit volume and x is the compressibility. For CsBr (b.c.c. structure) γ appears to be nearly independent of temperature, with a value of 2·0 but for the other crystals, which have the rock-salt structure, the parameter γ varies with temperature, chiefly betw een θ/10 and θ/5. At room temperature, γ lies between 1·45 and 1·7 but at low temperature this generally decreases to a value γ 0 which is ca. —0·1 for RbI, +0·3 for KCl, KBr and KI and 1·0 for NaCl and Nal; LiF does not show this decrease, γ 0 being 1·7. The values observed for γ 0 are compared with those calculated from elastic constants and their pressure derivatives and the general behaviour of γ( T ) is observed to conform qualitatively to the predictions of simple theoretical models of Born, Blackman and Barron.

The effects of Bi4Ti3O12 interfacial ferroelectric layer on the dielectric properties of Au/n-Si structures

2015 ◽  
Vol 29 (18) ◽  
pp. 1550120 ◽  
Author(s):  
Muharrem Gökçen ◽  
Mert Yıldırım
Keyword(s):  
Dielectric Properties ◽  
Interfacial Layer ◽  
Room Temperature ◽  
Complex Modulus ◽  
Semiconductor Interface ◽  
High Frequencies ◽  
Polarization Voltage ◽  
Versus Bias Voltage ◽  
Ferroelectric Layer ◽  
Polarization Mechanism

Au/n-Si metal-semiconductor (MS) and Au/Bi4Ti3O12/n-Si metal-ferroelectric-semiconductor (MFS) structures were fabricated and admittance measurements were held between 5 kHz and 1 MHz at room temperature so that dielectric properties of these structures could be investigated. The ferroelectric interfacial layer Bi4Ti3O12 decreased the polarization voltage by providing permanent dipoles at metal/semiconductor interface. Depending on different mechanisms, dispersion behavior was observed in dielectric constant, dielectric loss and loss tangent versus bias voltage plots of both MS and MFS structures. The real and imaginary parts of complex modulus of MFS structure take smaller values than those of MS structure, because permanent dipoles in ferroelectric layer cause a large spontaneous polarization mechanism. While the dispersion in AC conductivity versus frequency plots of MS structure was observed at high frequencies, for MFS structure it was observed at lower frequencies.

Preparation and Structural Characterization of CaCu3Ti4O12 Doped with Nickel, Ferrite, Manganese and Cobalt

2014 ◽  
Vol 893 ◽  
pp. 69-74
Author(s):  
Johar Banjuraizah ◽  
Mohd. Haziq Che Ani ◽  
A.R. Mohamed
Keyword(s):  
Dielectric Properties ◽  
Room Temperature ◽  
Synthesis Method ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Value ◽  
Small Grains ◽  
Dielectrical Properties

Transition metal oxide-doped CCTO (CaCu3Ti4O12) ceramics were prepared by a conventional solgel synthesis method and the effects of pure CCTO and CCTO doped with Mn, Fe, Co, Ni to the crystal structure, microstructures and dielectrical properties of samples were investigated. The phase composition and microstructure were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD analysis reveals that all samples exhibited multiphases with the pseudo-perovskite cubic CCTO phase with space group Im-3 as the main phase in undoped and doped CCTO samples. Peaks of monoclinic CuO and peroveskite CaTiO3 could also be seen in all samples which indicate that solid solution of CuO in CaTiO3 lattice was incomplete.SEM results show that doping effectively enhanced densification. SEM micrographs also suggested that the morphologies of doped CCTO ceramics had showed a matrix consisting of large grains wherein the small grains were embedded between the larger grains. Dielectric properties of pure and doped CCTO were investigated in a broad frequency range of the dielectric constant reached a value as high as εr = 29.4 at room temperature for CCTO doped with Ni at frequency (1000 Hz). Besides the sintering conditions, the microstructure and the dielectric properties of the CCTO are strongly influenced by type of doping elements.

scholarly journals Влияние магнитного поля на диэлектрическую проницаемость композита 80%La-=SUB=-0.7-=/SUB=-Sr-=SUB=-0.3-=/SUB=-MnO-=SUB=-3-=/SUB=-/20%GeO-=SUB=-2-=/SUB=-

2018 ◽  
Vol 60 (1) ◽  
pp. 61
Author(s):  
Ю.В. Кабиров ◽  
В.Г. Гавриляченко ◽  
А.С. Богатин ◽  
Е.И. Ситало ◽  
В.К. Яценко
Keyword(s):  
Magnetic Field ◽  
Dielectric Properties ◽  
Dielectric Permittivity ◽  
Magnetic Fields ◽  
Percolation Threshold ◽  
Room Temperature ◽  
High Conductivity ◽  
Frequency Range ◽  
Two Phase

AbstractThe dielectric properties of a magnetoresistive conducting two-phase 80%La_0.7Sr_0.3MnO_3/20%GeO_2 (wt %) composite have been studied near the percolation threshold in magnetic fields from 0 to 15 kOe at frequencies of the measurement field from 5 kHz to 1 MHz. The samples have inductive impedances; i.e., their permittivities can be considered negative due to a high conductivity in this frequency range. The permittivity increases in magnitude in magnetic field, and the values of the magnetodielectric coefficient reach 23% at room temperature. The reasons for the effect of magnetic field on the dielectric permittivity of samples are discussed.

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