نتایج جستجو برای: dielectric permittivity

تعداد نتایج: 41832  

Journal: :The Journal of chemical physics 2013
Vikram Jadhao Francisco J Solis Monica Olvera de la Cruz

In biological and synthetic materials, many important processes involve charges that are present in a medium with spatially varying dielectric permittivity. To accurately understand the role of electrostatic interactions in such systems, it is important to take into account the spatial dependence of the permittivity of the medium. However, due to the ensuing theoretical and computational challe...

2001
S. Kamba J. Petzelt E. Buixaderas D. Haubrich P. Vaněk P. Kužel

High-frequency dielectric properties of A5B4O15 ~A5Ba, Sr, Mg, Zn, Ca; B5Nb, Ta! dielectric ceramics are studied by means of the microwave cavity technique, a combination of far-infrared reflection and transmission spectroscopy and time-resolved terahertz transmission spectroscopy. Microwave permittivity e8 and Q3 f factor vary, depending on the chemical composition, between 11 and 51, and 2.4 ...

2017
Jinghui Gao Yan Wang Yongbin Liu Xinghao Hu Xiaoqin Ke Lisheng Zhong Yuting He Xiaobing Ren

Although dielectric energy-storing devices are frequently used in high voltage level, the fast growing on the portable and wearable electronics have been increasing the demand on the energy-storing devices at finite electric field strength. This paper proposes an approach on enhancing energy density under low electric field through compositionally inducing tricriticality in Ba(Ti,Sn)O3 ferroele...

Journal: :ACS nano 2013
Lisa A Fredin Zhong Li Michael T Lanagan Mark A Ratner Tobin J Marks

The high-frequency dielectric response of 0-3 polypropylene nanocomposites prepared with the activated metallocene polymerization catalyst [rac-ethylenebisindenyl]zirconium dichlororide absorbed on the native Al(2)O(3) surfaces of metallic aluminum nanoparticles is characterized. The nanocomposites produced are randomly dispersed in the polyolefin matrix with no visible defects that might degra...

2008
B. Geyer G. L. Klimchitskaya

The analytic asymptotic expressions for the Casimir free energy, pressure and entropy at low temperature in the configuration of one metal and one dielectric plate are obtained. For this purpose we develop the perturbation theory in a small parameter proportional to the product of the separation between the plates and the temperature. This is done using both the simplified model of an ideal met...

Journal: :Optics express 2011
A García-Etxarri R Gómez-Medina L S Froufe-Pérez C López L Chantada F Scheffold J Aizpurua M Nieto-Vesperinas J J Sáenz

High-permittivity dielectric particles with resonant magnetic properties are being explored as constitutive elements of new metamaterials and devices. Magnetic properties of low-loss dielectric nanoparticles in the visible or infrared are not expected due to intrinsic low refractive index of optical media in these regimes. Here we analyze the dipolar electric and magnetic response of lossless d...

Journal: :The journal of physical chemistry letters 2013
Alexander A Govyadinov Iban Amenabar Florian Huth P Scott Carney Rainer Hillenbrand

Scattering-type scanning near-field optical microscopy (s-SNOM) and Fourier transform infrared nanospectroscopy (nano-FTIR) are emerging tools for nanoscale chemical material identification. Here, we push s-SNOM and nano-FTIR one important step further by enabling them to quantitatively measure local dielectric constants and infrared absorption. Our technique is based on an analytical model, wh...

2005
C. K. Wong C. H. Tsang F. G. Shin

The bias-field-dependent dielectricity of ferroelectric thin films is studied by use of a multilayer model capable of modeling saturated and unsaturated hysteresis behavior under arbitrary fields. The simulated minor hysteresis loops at different bias fields are used to calculate the variation of dielectric permittivity with the bias field. The -E loops show asymmetric shifting along the field ...

2014
Aurelien Destruel Jin Jin Feng Liu Mingyan Li Ewald Weber Stuart Crozier

INTRODUCTION: It has been shown that high-permittivity dielectric pads can be used to efficiently improve the field homogeneity in the region of interest (ROI) in high-field MRI [1-8]. Recent studies focused on the design of these pads by controlling parameters such as size, position and permittivity, using simple patient specific parameter sweeping to improve the transmit field in a small regi...

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