Browsing by Subject "Dielectric properties"

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    Dielectric behaviors at microwave frequencies and Mössbauer effects of chalcedony, agate, and zultanite
    (Institute of Physics Publishing, 2015) Parali L.; Şabikoʇlu I.; Tucek J.; Pechousek J.; Novak P.; Navarik J.
    In this study, dielectric properties within 8-12 GHz microwave frequencies, inductively coupled plasma-atomic emission spectrometry, Fourier transform infrared spectrometry, synchronized two thermal analyses, and 57Fe Mössbauer spectroscopy analysis of chalcedony, agate, and zultanite samples from Turkey are presented. Agate and chalcedony show the same nine vibrational absorption peaks obtained unlike zultanite from FTIR spectra in the 350 cm-1 to 4000 cm-1 range, ε′ values of chalcedony, agate and zultanite derived at 10.5 GHz were 4.67, 4.41, and 7.34, respectively, ε′ and ε″ values of the studied samples at the microwave frequencies are related to the percentage weight of their constituent parts in their chemical compositions. 57Fe Mössbauer spectroscopy results confirm the existence of iron-containing islands in the crystal structure of zultanite, agate, and chalcedony samples, equipped them with magnetic features typical for magnetic nanoparticles including superparamagnetism. The presence of iron-containing islands significantly affects the magnetic, dielectric, and optical properties of studied samples that are not observed for pure minerals without any foreign inclusions. © 2015 Chinese Physical Society and IOP Publishing Ltd.
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    Dielectric properties of polystyrene/alumina composites for microelectronic devices
    (European Conference on Composite Materials, ECCM, 2016) Baştürk S.B.; Yalamaç E.; Gültekin S.
    The availability/lightness of electronic equipments in automotive, telecommunication and computer sectors have great importance in terms of the cost decrease and usability in high speed applications. Printed circuit boards (PCBs) are the main components of these systems and composed of two basic elements: substrate and passive electronic devices. Microelectronic segments having low dielectric permittivity (dielectric constant) and loss tangent minimize the capacitive coupling effects and decrease the signal attenuation. Ceramic particle filled polymer composites combine the desired dielectric properties and have been employed in electronic industry. In this study, 5%, 15% and 30% wt. alumina (Al2O3) loaded polystyrene (PS) composites were produced. The size of the PS granules was reduced below 100 microns by ball milling process. The Al2O3 and PS powders were mixed by vibratory disc mill and subjected to injection molding for manufacturing the circular specimens. The dielectric permittivity (real and imaginary parts) and loss tangent parameters of the composites were measured via dielectric analyzer up to 1 MHz at room temperature. Based on dielectric measurements, there was no pronounced difference among the samples' real part permittivities along the frequency variation. As expected, the ceramic content increase led to the increase of permittivity and 30%Al2O3 wt. loaded structure showed the maximum values. This behavior was attributed to the effect of polarization which appears in heterogeneous media consisting of phases with different dielectric constant and conductivity. © 2016, European Conference on Composite Materials, ECCM. All rights reserved.