Showing papers by "Pawan K. Khanna published in 2006"
TL;DR: HCl:CdS nanocomposite showed λ (max) at about 450-460 nm in addition to the bands at ∼320 and ∼600 nm due to polyaniline as mentioned in this paper.
53 citations
TL;DR: In this paper, the authors presented the generation of CdO and Cd(OH) 2 nano-particles from Dimethyl Cadmium in DMF, where the reaction was done in the presence of 1,2,3-selenadiazole (the source of selenium) with Me 2 Cd in the DMF (product- I ).
51 citations
TL;DR: In this paper, a single step polymerization process was used to synthesize the conducting emeraldine salt phase of poly(N-methyl aniline) (PNMA), doped with different acids (viz. HCl, HClO4, H3PO4, h3BO3 and acetic acid).
Abstract: Poly(N-methyl aniline) (PNMA), doped with different acids (viz. HCl, HClO4, H3PO4, H3BO3 and acetic acid) was synthesized by a chemical polymerization method using ammonium persulphate as an oxidizing agent. This is a single step polymerization process to synthesize directly the conducting emeraldine salt phase of the polymer. The synthesized polymers were characterized by UV–vis, TGA/SDTA and conductivity measurements. These polymers were then successfully utilized as humidity sensors. The change in resistance with respect to % relative humidity (% RH) was observed, when pressed pellets of the polymers were exposed to a broad range of humidity (20–100% RH). Among the different acids used for the doping purpose of the polymer, the H3PO4-doped polymer showed the best sensing response and was found to be the best candidate for a humidity sensor.
48 citations
TL;DR: In this article, in situ preparation of CdSe nanoparticles using poly(vinyl alcohol) [PVA] and polymethylmethacrylate [PMMA] as matrices by use of organoselenium compound.
35 citations
TL;DR: Indium phosphide nanocrystals have been synthesized by the direct reaction of sodium phosphide and indium trichloride pre-combined with n -trioctylphosphine in 4-ethylpyridine as a suitable solvent for terminating the particles growth as mentioned in this paper.
31 citations
TL;DR: In this paper, a single step chemical polymerization of N-methyl aniline was carried out by using ammonium persulphate as an oxidizing agent, which was found to have very good physicochemical properties and good electrical conductivity.
Abstract: Single step chemical polymerization of N-methyl aniline was carried out by using ammonium persulphate as an oxidizing agent. The conducting emeraldine salt phase of the polymers using camphor sulfonic acid and p-toluene sulfonic acid as dopants was made by a direct process. The polymers were characterized by UV-vis and FTIR spectroscopy, scanning electron microscopy, TGA, and conductivity measurements. The synthesized polymers were found to have very good physicochemical properties and good electrical conductivity. Conductivity measurements have shown “thermal activated behavior.” The change in resistance with respect to % relative humidity (RH) was observed, when pressed pellets of the polymer were exposed to the broad range of humidity (ranging between 20 and 100% RH). © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 812–820, 2006
19 citations
TL;DR: In this article, the effect of temperature on particles diameter is studied and the XRD measurement showed that higher temperature is favorable for layered nanocrystals of PbSe and NIR measurement shows that absorption at 3.31 μm is due to size quantization effect thus increasing the band gap energy from 0.27 to 0.56 eV.
18 citations
TL;DR: In this article, a slightly broadened X-ray diffraction pattern for pure beta silver selenide (β-Ag 2 Se) was observed, which indicated that the agglomerated particles could be in the range of about 100 to 200 nm in dimension.
15 citations
TL;DR: It is found that when silver nitrate is reduced by TOP, spherical silver nano-particles with poor redispersity are formed but extended heating results in formation of long silver rods of micrometer size however, the re-dispersible nano- particles are easily formed when silver carboxylates are reduced byTOP.
Abstract: Neat n-Trioctylphosphine (TOP) has been used for the first ever time for reduction of silver nitrate and silver carboxylates (citrate, oleate, and myristate) under mild thermal reaction conditions. UV. visible absorption measurements of re-dispersible silver particles that were obtained by reduction of silver myristrate (product-IV) and silver nitrate (product-I) showed surface plasmon resonance absorption peak at 400 nm. The powder XRD pattern of fcc zero-valent silver resulted in diameters in the range of about 25-30 nm. TEM analysis showed particle diameter similar to that was observed by the XRD. FTIR spectroscopy revealed that the organics from the carboxylate group are retained by the nano-particles in case of product-IV however, presence of TOP is observed in product-I. It is found that when silver nitrate is reduced by TOP, spherical silver nano-particles with poor redispersity are formed but extended heating results in formation of long silver rods of micrometer size however, the re-dispersible nano-particles are easily formed when silver carboxylates are reduced by TOP.
15 citations
TL;DR: In this paper, conducting polyaniline doped with polymeric acids was synthesized by a in situ chemical polymerization method and the synthesized polymers were characterized by using UV-visible, FT-IR spectroscopy and SEM analysis.
Abstract: Conducting polyaniline doped with polymeric acids was synthesized by a in situ chemical polymerization method. The synthesized polymers were characterized by using UV‐Visible, FT‐IR spectroscopy and SEM analysis. Thermal stability of these polymers was evaluated by using TGA/DSC analysis. Among the three polymeric acids used for doping purpose, poly(vinyl sulphonic acid) doped polyaniline is found to be more conducting than those doped with other acids. From the temperature dependent conductivity measurements, an increase in conductivity with increase in temperature was observed.
12 citations
TL;DR: In this article, a single step polymerization of poly(o-toluidine) was carried out by using ammonium persulphate as an oxidizing agent and the formation of the conducting emeraldine salt phase of the polymer was confirmed by the UV-visible and FT-IR spectroscopic analysis.
Abstract: Single step polymerization of poly(o‐toluidine) was carried out by using ammonium persulphate as an oxidizing agent. Formation of the conducting emeraldine salt phase of the polymer was confirmed by the UV‐visible and FT‐IR spectroscopic analysis. The elemental composition of the polymer was evaluated by using a CHNS analyzer. Thermal stability of these polymers was investigated by the thermogravimetric analysis. Among the three polymeric acids used for doping purposes, poly(acrylic acid) doped material was found to show less thermal stability compared to poly(styrene sulphonic acid) and poly(vinyl sulphonic acid) doped poly(o‐toluidine).
TL;DR: The Second Harmonic Generation (SHG) studies show improvement in intensity with increasing m-NA concentration up to a saturation point (approximately 2.52 wt% with respect to PVA).
Abstract: Meta-nitroaniline (m-NA) doped silver/poly(vinylalcohol) (Ag/PVA) nanocomposites are prepared via in-situ reduction of silver salt by employing hydrazine hydrate (HH) in order to study the effect of the NLO active m-NA on the optical properties of nanoparticles of silver in the colloidal as well as self supported film form. Reduction of silver salt in aqueous alcoholic PVA with HH is done first followed by doping of the reaction mixture with m-NA. The UV-Visible absorption spectra show peak at about 400 nm for Ag nanoparticles due to surface plasmon resonance phenomenon, which gets blue shifted with the change in m-NA concentration. The Second Harmonic Generation (SHG) studies show improvement in intensity with increasing m-NA concentration up to a saturation point (approximately 2.52 wt% with respect to PVA). Further increase in m-NA concentration leads to decrease in SHG intensity. The solutions and the films are characterized by photoluminescence (PL), FTIR spectroscopy, XRD, SEM, TEM, and thermal analysis. m-NA doped composites showed better PL efficiency. SEM of the nanocomposite film shows uniform distribution of particles within the film. The particle size as shown by TEM is found to be less than 10 nm.
TL;DR: In this article, the first report on synthesis of compound 1 at normal pressure is presented, which is also for the first time, obtained by self dimerisation of the parent 1,2,3−selenadiazole due to possible photolysis, over prolonged storage in the refrigerated conditions.
Abstract: Dicycloocta‐(1,4)‐diselenin, I is prepared by heating cycloocteno‐1,2,3‐selenadaizole in various high boiling solvent such as ethylene glycol, dimethylsulfoxide (DMSO), N,N'‐dimethylformamide (DMF) and Xylene. Pale yellow crystalline product is characterized by absorption spectroscopy, proton and carbon NMR, elemental analysis and by mass spectrometry. This is the first report on synthesis of compound 1 at normal pressure. The compound 1 is also for the first time, obtained by self dimerisation of the parent 1,2,3‐selenadiazole due to possible photolysis, over prolonged storage in the refrigerated conditions.
TL;DR: In this paper, conducting poly(o-anisidine) doped with polymeric acids was synthesized by in-situ chemical polymerization method using ammonium persulphate as an oxidizing agent.
Abstract: Conducting poly(o-anisidine) doped with polymeric acids [viz, poly(styrene sulphonic acid) (PSSA), poly(vinyl sulphonic acid) (PVSA) and poly(acrylic acid) (PAA)] was synthesized by in-situ chemical polymerization method using ammonium persulphate as an oxidizing agent. This is a single-step polymerization process for the direct synthesis of emeraldine salt phase of the polymer. The polymers were characterized by using UV-Vis., FT-IR spectroscopy, thermal analysis, and conductivity measurements. Formation of mixed phases of polymer together with conducting emeraldine salt phase are confirmed by spectroscopic techniques. Thermal analysis shows that PAA doped poly(o-anisidine) undergoes three stage decomposition pattern similar to unsubstituted polyaniline. While, in PSSA and PVSA, doped sample splitting up of the second weight loss stage is observed leading to a four-step decomposition pattern. Room temperature conductivity measurements show less conductivity in poly(o-anisidine) than in polyanili...