Effect of controlled doping on electrical properties and permittivity of PTSA doped polyanilines and their EMI shielding performance

Emeraldine base (EB) has been protonated with different concentration of para-toluene sulfonic acid (PTSA) to form doped polyanilines (PANIs). These samples have been characterized by various techniques and a detailed correlation between dopant concentration and structural, thermal, electrical and electromagnetic properties has been established. The FTIR/UV-Visible and EPR spectra confirm the formation of polarons as proto-generated charge carriers whose concentration follows the dopant concentration trend. It was also observed that increase in doping level leads to systematic improvement of electrical conductivity (1.2x1(-9) to 5.3 S/cm) as well as complex permittivity (epsilon'similar to 5.5 & epsilon"-0.6 to epsilon'similar to 22.3 & epsilon"similar to 24.6) with parallel improvement of electromagnetic (EM) radiation blocking capacity from -3.8 dB (for EB) to -23.9 dB (for 1.0 M PTSA doped Sample). Further, the attenuation was found to be critically dependent on dopant concentration, complex permittivity and electrical conductivity revealing that both polarization as well as conduction is important for achieving high attenuation. It was also observed that reflection is main phenomenon at low doping level whereas absorption becomes increasingly important at higher doping levels and extends dominant contribution towards total attenuatio

Morphology of Atmospheric Particles over Semi-Arid Region (Jaipur, Rajasthan) of India: Implications for Optical Properties

The regional dust morphology and spectral refractive indices (RIs; governed by hematite, Fe2O3 content at short wavelengths) are key elements for ascertaining direct radiative forcing of mineral dust aerosols. To provide morphological features of background mineral dust from a semi-arid zone in the vicinity of the Thar Desert, we carried out an expedition to the Jaipur city during late winter of 2012. Morphological analysis reveals the predominance of "Layered", "Angular" and "Flattened" particles, while the frequency distribution of a total of 235 dust particles shows the aspect ratio, AR and circularity parameter, CIR (measures of particle's non-sphericity) typically similar to 1.4 and similar to 0.8, respectively. Sensitivity analysis at 550 nm wavelength reveals the equivalent sphere model may underestimate Single Scattering Albedo, SSA for the dust with low (similar to 1.1%) hematite by similar to 3.5%. Both underestimation (by similar to 5.6%) and overestimation (up to 9.1%) are probable in case of dust with high hematite content (similar to 5.68%). In addition, the effect of AR on the dust scattering is significant in case of dust with high hematite content. More such regionally representative dust morphological data are required for better estimation of regional radiative forcing of mineral dust aerosols

Effect of controlled doping on electrical properties and permittivity of PTSA doped polyanilines and their EMI shielding performance

175-182Emeraldine base (EB) has been protonated with different concentration of para-toluene sulfonic acid (PTSA) to form doped polyanilines (PANIs). These samples have been characterized by various techniques and a detailed correlation between dopant concentration and structural, thermal, electrical and electromagnetic properties has been established. The FTIR/UV-Visible and EPR spectra confirm the formation of polarons as proto-generated charge carriers whose concentration follows the dopant concentration trend. It was also observed that increase in doping level leads to systematic improvement of electrical conductivity (1.21<span style="font-family:Symbol;mso-ascii-font-family: " times="" new="" roman";mso-hansi-font-family:"times="" roman";mso-char-type:symbol;="" mso-symbol-font-family:symbol"="" lang="EN-GB">-9 to 5.3 S/cm) as well as complex permittivity (ε'~5.5 & ε"~0.6 to ε'~22.3 & ε"~24.6) with parallel improvement of electromagnetic (EM) radiation blocking capacity from -3.8 dB (for EB) to <span style="font-family:Symbol;mso-ascii-font-family: " times="" new="" roman";mso-hansi-font-family:"times="" roman";mso-fareast-language:="" en-sg;mso-char-type:symbol;mso-symbol-font-family:symbol"="" lang="EN-GB">-23.9 dB (for 1.0 M PTSA doped sample). Further, the attenuation was found to be critically dependent on dopant concentration, complex permittivity and electrical conductivity revealing that both polarization as well as conduction is important for achieving high attenuation. It was also observed that reflection is main phenomenon at low doping level whereas absorption becomes increasingly important at higher doping levels and extends dominant contribution towards total attenuation.<span style="mso-ansi-language:EN-IN;mso-fareast-language: EN-IN"> </span

Effect of controlled doping on electrical properties and permittivity of PTSA doped polyanilines and their EMI shielding performance

Emeraldine base (EB) has been protonated with different concentration of para-toluene sulfonic acid (PTSA) to form doped polyanilines (PANIs). These samples have been characterized by various techniques and a detailed correlation between dopant concentration and structural, thermal, electrical and electromagnetic properties has been established. The FTIR/UV-Visible and EPR spectra confirm the formation of polarons as proto-generated charge carriers whose concentration follows the dopant concentration trend. It was also observed that increase in doping level leads to systematic improvement of electrical conductivity (1.21-9 to 5.3 S/cm) as well as complex permittivity (ε'~5.5 &amp; ε"~0.6 to ε'~22.3 &amp; ε"~24.6) with parallel improvement of electromagnetic (EM) radiation blocking capacity from -3.8 dB (for EB) to -23.9 dB (for 1.0 M PTSA doped sample). Further, the attenuation was found to be critically dependent on dopant concentration, complex permittivity and electrical conductivity revealing that both polarization as well as conduction is important for achieving high attenuation. It was also observed that reflection is main phenomenon at low doping level whereas absorption becomes increasingly important at higher doping levels and extends dominant contribution towards total attenuation

Growth of thermally evaporated SnO2 nanostructures for optical and humidity sensing application

Nanoscaled spherical, facetted-spherical and octahedral shapes of high yield and economically viable tin oxide (SnO2) was synthesized using direct sublimation process employing thermal evaporation at 1350 C without any catalyst. The crystalline structure and morphology of SnO2 nanostructures were characterized using X-ray diffraction and electron microscopy. The morphology reveals that the reaction time, that is evaporation time, is important for successful synthesis of different shape and size of SnO2 nanostructures. High resolution transmission electron microscopy exhibited the particle size of SnO2 between 5 and 6 nm. Nanoscale morphological tuning in size and shape facilitates alteration in optical band gap, absorption and photolumiscence properties. The humidity sensor based on spherical SnO2 nanostructures demonstrates an excellent sensitivity with an increase in relative humidity (RH) at room temperature

Synthesis and characterization of petal type CZTS by stacked layer reactive sputtering

Here we present a method to grow the petal type structure of CZTS thin film on soda lime glass substrate using the stacked layer reactive sputtering and post-depostion annealing in N-2 atmosphere. Optical bandgap of the petal type structure of CZTS was determined using UV-VIS spectroscopy and the value was 1.5 eV. In XRD analysis, (112) plane having highest intensity and other supporting planes with low intensity peaks corresponding to (200), (220) and (312) revealed the presence of CZTS phase. It was further confirmed by the Raman analysis, where the Raman peaks at 288 cm(-1), 335 cm(-1) and 353 cm(-1) revealed the presence of CZTS phase. Petal type growth was observed in the scanning electron microscopy analysis. Elemental analysis was done by the EDAX. In EDAX analysis, It is observed that sample was Sn rich which may be responsible for petal type growth. Petal type growth of CZTS may be helpful in increasing the performance of the CZTS based thin film solar cell by phenomena of light scattering and enhanced surface area

Facile synthesis of 2-dimensional transparent graphene flakes for nucleic acid detection

We report on the synthesis of 2-dimensional transparent graphene flakes (GF; 2.2 mu m x 50 mu m), onto indium-tin-oxide (ITO) coated glass plates, by electrochemical exfoliation of graphite rods using in situ intercalation of potassium ions. Raman spectroscopy, Fourier transform infra-red (FT-IR) spectroscopy, scanning electron microscopy and transmission electron microscopy, are used to probe the formation of graphene structures, revealing the generation of GF. Synthesized GF are employed as DNA immobilization platform for genosensor design for Mycobacterium tuberculosis detection. This GF based biosensing electrode exhibits high sensitivity, fast response and wide detection range etc. These findings are important for cost-effective strategy for the production of GF for application to advanced biosensors, and to understand graphene-based biosensing mechanism specifically for nucleic acid detection