s. Suresh; v. Seetharaman; R. Mohan Kumar
Abstract
p-Toludinium fumarate (PTF) a potential organic single crystal was grown by slow evaporation solution growth technique. Single crystal X-ray diffraction study was used to compute the unit cell parameters. The nuclear magnetic resonance spectral study reveals the proton and carbon molecular structure ...
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p-Toludinium fumarate (PTF) a potential organic single crystal was grown by slow evaporation solution growth technique. Single crystal X-ray diffraction study was used to compute the unit cell parameters. The nuclear magnetic resonance spectral study reveals the proton and carbon molecular structure of PTF crystal. Optical band gap and the percentage of optical transmission were established by using UV-visible spectroscopy. Photoluminescence studies show that emission is independent of excitation wavelength. Dielectric constant (ε') and dielectric loss (tan δ) of PTF crystal were studied. The third order nonlinear refractive index (n2) and third order nonlinear absorption coefficient (β) were estimated by Z-scan technique.
Rajesh Kalia; J. K. Sharma; Sapna Kalia
Abstract
The dielectric constant (ε') and dielectric loss (ε״) of pristine and C5+ (70 MeV) ion irradiated samples of the PEEK have been investigated with the variation of temperature at different frequencies (100 Hz, 1 kHz, 10 kHz and 100 kHz). The maxima are obtained around 170 oC in dielectric ...
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The dielectric constant (ε') and dielectric loss (ε״) of pristine and C5+ (70 MeV) ion irradiated samples of the PEEK have been investigated with the variation of temperature at different frequencies (100 Hz, 1 kHz, 10 kHz and 100 kHz). The maxima are obtained around 170 oC in dielectric constant (ε') vs. temperature (T) curve. This relaxation is linked with the movement of ketone (>C=0) dipoles linked to the main chain. The irradiation of polymers increases the orientational polarization due to increase in number of dipoles with fluence. The increase in dielectric constant (ε') and dielectric loss (ε'') is attributed to chain scissioning at higher fluence which results in an increase of free radicals and unsaturations. Copyright © 2018 VBRI Press.
Nandeibam Nilima; Mamata Maisnam; Sumitra Phanjoubam
Abstract
Li-Ni-Co ferrite/SiO2 composites with representative formula Li0.41Ni0.1Co0.08Fe2.41O4+ xSiO2 (i.e., x = 0wt. %, 5wt. %,10wt. % and 20wt. %) were prepared by sol-gel method. The prepared composites were pre-sintered at 600ºC for 2 hrs and then finally sintered at 1000ºC for 6 hrs. X-ray diffraction ...
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Li-Ni-Co ferrite/SiO2 composites with representative formula Li0.41Ni0.1Co0.08Fe2.41O4+ xSiO2 (i.e., x = 0wt. %, 5wt. %,10wt. % and 20wt. %) were prepared by sol-gel method. The prepared composites were pre-sintered at 600ºC for 2 hrs and then finally sintered at 1000ºC for 6 hrs. X-ray diffraction studies showed diffraction peaks indicating single phase with spinel structure. However, peaks of SiO2 were found in composites of higher (x). The microstructure of the samples was studied by using Scanning Electron Microscopy. The crystallite size and average grain size were found to decrease with increase of SiO2 content. The room temperature frequency variation of dielectric constant and dielectric loss was measured from 100Hz-1MHz and they showed a dispersive behavior. The variation has been explained by Verwey mechanism of electron hopping and Koop’s two-layer model. The addition of SiO2 plays significant role in influencing the various structural, microstructural and electrical properties. Uniform and refined microstructures are observed with the addition of SiO2 and this reduces the value of dielectric constant and loss significantly, which is desirable for high frequency applications. The results obtained and mechanisms involved are discussed. Copyright © 2017 VBRI Press.
Sanatombi Sorokhaibam; Ibetombi Soibam; Sumitra Phanjoubam
Abstract
Substituted lithium ferrite having the chemical formula Li0.35 Ni0.1 Mn0.1 Zn0.2 Fe2.35 O4 have been synthesized by the citrate precursor method. The sample was given pre-sintering at 650oC in a conventional furnace. Final sintering was carried out at 900oC in a conventional surface and another ...
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Substituted lithium ferrite having the chemical formula Li0.35 Ni0.1 Mn0.1 Zn0.2 Fe2.35 O4 have been synthesized by the citrate precursor method. The sample was given pre-sintering at 650oC in a conventional furnace. Final sintering was carried out at 900oC in a conventional surface and another in a microwave furnace. The spinel phase structure of the conventional (CS) and microwave sintered (MS) samples was confirmed by the XRD patterns. From the analysis of XRD data, the crystallite size of the samples was estimated and smaller crystallite size was observed in the microwave sintered sample. Scanning Electron Microscopy (SEM) was also carried out. The dielectric studies were investigated. Room temperature dielectric constant ( ) and dielectric loss (tan d) were studied as a function of frequency. Experimental results show dispersion for variation of dielectric constant and dielectric loss tangent with frequency for both CS and MS sample. However, microwave sintered sample show lower dielectric constant and losses. Possible mechanism is being discussed. Copyright © 2016 VBRI Press.
Sathosh K. Kurni; Pradip Paik
Abstract
SiO2 nanoparticles of average size 15-20 nm have been synthesized and its dielectric properties have been investigated as a function of frequency (between 20 Hz to 2 MHz). A very high dielectric constant of ca. 14000 at 20 Hz and at room temperature has been observed which is very high compared to the ...
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SiO2 nanoparticles of average size 15-20 nm have been synthesized and its dielectric properties have been investigated as a function of frequency (between 20 Hz to 2 MHz). A very high dielectric constant of ca. 14000 at 20 Hz and at room temperature has been observed which is very high compared to the conventional bulk SiO2 particles (ca. 50-100). For this new SiO2 the loss value is found to be less than 1. These SiO2 nanoparticles with high dielectric constant and low loss can be offered its use in constructing high efficient electronic circuit boards and storage devices. Spectra between real and imaginary parts of dielectric constant reveal an inclined line with depressed semicircle. Impedance measurements have been performed to know the electrical properties of the novel SiO2 nanoparticles. XRD, TEM and FTIR characterizations confirm the solid state network structural, morphological shape and size, and chemical functionality of SiO2 respectively. Copyright © 2016 VBRI Press
