Results 1 - 10 of 7268
Results 1 - 10 of 7268. Search took: 0.049 seconds
|Sort by: date | relevance|
[en] The impedance spectrum of TlGaSe2 crystal implanted with He+ ions (with 150keV-energy He+ ions) has been investigated at the temperatures of 275-550 K and frequencies of 100-106 Hz. After the implantation, the numerical value of the permittivity and the relaxation period increased by 10 times. It has been shown that the main reason for the increase in the numerical value of permittivity as well as the relaxation period as a result of implantation is the increase in the concentration of mobile ions. It was found that the distribution of Tl in cavities is at the depth of 1000 nm.
[en] The surface resonances of a pair of spheres of different radii are studied using a local dielectric function to describe the response of each particle. All modes are characterized by values of -ε(ω) that diverge as the spheres approach touching. We show that to a good approximation these values depend only on the edge-to-edge separation measured in units of the smaller sphere, and not on the radius of the larger one
[en] A measuring facility based on a Q-meter system is described that provides the determination of the dielectric parameters of ceramics in the frequency range of 1-70 MHz. The dielectric parameters, the permittivity εr' and the loss tangent tan δ, are required for the selection of appropriate ceramic components in heating systems for nuclear fusion plasmas based on Ion-Cyclotron-Resonance Heating. The theory of dielectric measurements by Q-meters is presented in detail. Further the basic formulae for the transformation of the measurable variables into εr' and tan δ are developed for specimens with shapes of discs and rings. Their validity is checked for samples with diameters in the range of 30-50 mm and thicknesses in the range of 1-5 mm. A correction scheme is proposed for accounting for the influence of field distortion on the permittivity. The influence of statistical and systematic errors are investigated, and it is found that the uncertainties introduced by the correction of field distortion dominate for εr', whereas for tan δ the statistical error is generally most important. The accuracy achieved for εr' is better than ± 0.3, and the relative error of tan δ amounts to <10% for tan δ values in the range of 10-3-10-4. (orig.)
[de]Es wird eine Messeinrichtung auf der Grundlage eines Q-Meter-Systems beschrieben, die die Bestimmung der dielektrischen Parameter von Keramik im Frequenzbereich von 1-70 MHz erlaubt. Die dielektrischen Parameter, die Dielektrizitaetskonstante εr' und der Verlusttanges tan δ, werden zur Auswahl geeigneter keramischer Komponenten in Heizsystemen fuer Kernfusionsplasmen, die auf der Ionen-Zyklotron-Resonanz beruhen, benoetigt. Die Theorie dielektrischer Messungen auf der Basis von Q-Metern wird im Detail dargelegt. Weiterhin werden die grundlegenden Formeln zur Umwandlung der Messgroessen in εr' und tan δ fuer scheiben- und ringfoermigen Proben entwickelt. Ihre Gueltigkeit wird fuer Proben mit Durchmessern im Bereich von 30-50 mm und mit Dicken im Bereich von 1-5 mm ueberprueft. Ein Korrekturschema wird vorgeschlagen, mit dem der Einfluss von Feldverzerrungen auf die Dielektrizitaetskonstante beruecksichtigt werden kann. Der Einfluss statistischer und systematischer Fehler wird untersucht und es ergibt sich, dass die Ungenauigkeiten, die durch die Korrektur der Feldverzerrung eingefuehrt werden, fuer εr' ueberwiegen, waehrenddessen fuer tan δ der statistische Fehler in der Regel am bedeutendsten ist. Eine Genauigkeit von besser als ±0.3 wird fuer εr' erzielt und der relative Fehler in tan δ liegt unter 10% fuer Werte von tan δ im Bereich von 10-3-10-4. (orig.)
[en] The temperature dependences of the dielectric constant ε, the dielectric loss tangent tgδ, and the specific resistance ρ of nano composites based on low density polyethylene (LDPE) and cadmium sulfide nanoparticles (CdS) before and after gamma irradiation have been investigated. It has been shown that the change in the electrophysical parameters of irradiated LDPE/CdS nano composites depended both on the ratio of the rates of crosslinking and destruction processes, and on the improvement of the adhesive interactions of the polymer matrix with CdS nanoparticles in the polymer after exposure to radiation. It has been also shown that LDPE/CdS composites irradiated at a dose of 50 kGy had higher dielectric properties and more thermo stable.
[en] Full Text: Dielectric and polarizing properties of silver intercalated TIInS2< Ge> connection have been investigated. It was established, that intercalation extend the temperature area of Relaxor conditions. In c axis s direction of silver intercalated TIInS2< Ge> connection spontaneous polarization occurrence which revealed and its maximal value appreciated as 0,7.10-8Cl/cm2
[en] Pumping of a certain amount of disperse applications to the crystallized polyethylene, leads to changing of structural defects of polymers, the structure of their molecules, the degree of crystallization, the degree of alignment of macromolecules, changes, their electro active (electrets , piezoelectric , anti-static), dielectric and electro- physical , sensory , and other properties. In this case are expected spheroids polyethylene size reductions, changing of crystals, and formation of different functional groups and molecular top groups
[en] Present article is devoted to induced scattering. The equation for the induced scattering of the test wave in the field of random waves has been considered. The well known (from the theory of weak plasma turbulence) expression for the probability of the scattering on ions has been obtained. The consistency between the equations describing the process of wave scattering which are obtained from the general nonlinear (cubic in field) equation and those derived on the basis of the weak turbulence theory for the particular case of the test wave in stationary random field has been illustrated.
[en] This paper presents an experimental analysis of the dose effect during gamma irradiation of butadiene nitrile rubber nano composite samples. ZrO2 filled polymer were irradiated in the dose range of 100, 150, and 250 kGy in a Co60 irradiation source. The dielectric and optical properties of the irradiated materials were studied. The experimental results show an improvement in both of these parameters as dose increases, indicating the predominance of cross-linking over oxidative degradation. Also, was studied the morphology of nitrile rubber composites by SEM.