Browsing by Author "S.S. Sekhon"

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Effect of replacement of glass-modifier Ag2O by Na2O in silver borate ion-conducting glass
(Kluwer Academic Publishers, 1999) S.S. Sekhon; S. Chandra
Silver ion-conducting glasses having different compositions have been extremely studied. In particular, silver ion-conducting borate glass with composition, AgI-Ag2O-B2O3 and pure boron oxide glass. For a given ion-conducting glass system, the conductivity value can be varied/controlled by: varying the amount of network former; varying the amount of doping salt; using two alkali oxides; and adding two glass formers. The conductivity is found to increase in all cases except in the third case which shows a minima.
Ion transport in copper boromolybdate glasses
(1994) K.S. Sidhu; S.S. Sekhon; S. Chandra
Copper ion conducting glasses with mixed glass formers and having composition CuI+Cu2O+MoO3+B2O3 have been studied. The variation of room-temperature conductivity with glass composition has been found to be controlled by the variation in mobility of the mobile species and the number of Cu2+ ions present in the glass samples. The temperature variation of conductivity has been found to follow an Arrhenius relation. © 1994 IOP Publishing Ltd.
Ionic transport in polyethylene oxide-Cul polymer electrolyte
(Kluwer Academic Publishers, 1993) K.S. Sidhu; S.S. Sekhon; S.A. Hashmi; S. Chandra
[No abstract available]
Ionic/Electronic Charge Transport in Copper Molybdate Glasses Prepared under Different Conditions
(1994) K.S. Sidhu; S.S. Sekhon; S. Chandra
Copper glasses (CuI + Cu2O + MoO3) have been prepared by in-situ quenching of mixtures molten (i) in air (ii) under n2 being continuously flushed, (iii) in static vacuum with initial pressure of 10-6Torr and (iv) in vacuum being continuously pumped. The samples prepared under different conditions had different ionic/electronic transference number. The electronic part of conductivity has been explained in terms of Mo6+ -∗Mo5+ and Cu+ ↔ Cu+ + conversion. The presence of Cu++ and Mo5 + has been established by ESR studies. © 1994, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.
Mixed cation effect in silver borate ion conducting glass
(Kluwer Academic Publishers, 1999) S.S. Sekhon; S. Chandra
The partial replacement of silver iodide in ion conducting silver borate glass (Agl-Ag2O-B2O3) by sodium iodide has been carried out and its effect on the properties of the glass system has been studied. Conductivity studies show that with the simultaneous presence of two cations (Ag+ and Na+), mixed cation effect is observed. There is also lower solubility of Agl which crystallised out. The results obtained have been explained by data from X-ray diffraction, FTIR spectroscopy and conductivity vs. temperature studies.
PEO : AgSCN : Al2O3 - A new composite polymer electrolyte
(1996) S.S. Sekhon; G.S. Sandhar; S. Agnihotry; S. Chandra
Composite polymer electrolytes containing PEO, AgSCN and Al2O3 with different weight ratios of Al2O3 have been prepared. X-ray diffraction studies show the formation of complex. The addition of Al3O3 results in an increase in the room temperature conductivity of the PEO-AgSCN polymer electrolyte system.
PMMA based protonic polymer gel electrolytes
(Institute for Ionics, 2000) S. Chandra; S.S. Sekhon; Narinder Arora
The paper reports the synthesis of protonic polymer gel electrolytes containing different hydroxy benzoic acids (ortho-, meta- and para-) and aliphatic dicarboxylic acids. Gel electrolytes were prepared by adding polymethylmethacrylate (PMMA) in diffcrent weight ratios to the I M solution of above acids in a ternary solvent mixture of propylene carbonate (PC), cthylcne carbonate (EC) and dimethylformamide (DMF) in equal volume ratio. The conductivity of these gel electrolytes has been found to depend upon the amount of PMMA added to the system. A "Breathing Polymeric Chain Model" has been proposed to explain the variation of conductivity with PMMA concentration in these gel electrolytes.
Proton conducting polymer gel electrolytes with NO2 substituted carboxylic acids
(2003) S.S. Sekhon; Narinder Arora; S. Chandra
Proton conducting polymer gel electrolytes based on different nitro substituted aromatic carboxylic acids have been studied. The conductivity of solution and gel electrolytes containing these acids has been found to depend upon the dissociation/acidity constant value of the acid and varies as σ(ortho-) σ (meta-). The addition of polymethylmethacrylate (PMMA) modifies the conductivity of these gel electrolytes which depends upon the dissociation constant and concentration of the acid present. The rate of change of conductivity of gel electrolytes with gelling polymer (PMMA) has been found to be different in the low and high PMMA regions which has been explained to be due to different mechanisms being responsible for the modification of conductivity in the low and high PMMA regions. © 2003 Elsevier Science Ltd. All rights reserved.
Proton-conducting gel electrolyte
(2002) S. Chandra; S.S. Sekhon; Ritu Srivastava; Narinder Arora
Proton conduction in solid state xerogels and polymeric gels are reported. Xerogels, doped with known proton conductors, were prepared by "sol-gel" method starting either from inorganic precursor sodium metasilicate (termed as hydrogel) or organic precursor tetraethyl orthosilicate (termed as silica or SiO2 alcogel). The dopants chosen for the former were NH4BF4, NH4Cl, NH4H2PO4 and N2H6SO4, while for the latter, the dopants used were H3PO4, NH4BF4, NH4H2PO4 and KH2PO4. The SiO2:H3PO4 alcogel gave the highest room temperature conductivity (10-3 S cm-1). Some of the xerogels studied by us were stable even up to 300 °C. Another interesting group of proton-conducting materials discussed in this paper is polymeric gel which was prepared by dispersing PMMA in the liquid electrolyte obtained by dissolving o-, m-, p-hydroxybenzoic acid; o-, m-, p-nitrobenzoic acid and three dicarboxylic acids, viz., oxalic, malonic and succinic acid, in a high-dielectric constant organic solvent. The role of the dissociation constants of the dissolved acids and the interaction of the polymer were discussed. The addition of polymer, inspite of the increasing viscosity, was found to sometimes lead to an increase in the conductivity of liquid electrolyte, which was explained on the basis of a breathing polymer chain model. © 2002 Elsevier Science B.V. All rights reserved.
Protonic polymer gel electrolytes based on carboxylic acids: Ortho and inductive effects
(2002) S.S. Sekhon; N. Arora; B. Singh; S. Chandra
The conductivity of polymer gel electrolytes containing three aromatic and three aliphatic carboxylic acids has been studied, viz. (i) ortho-, meta- and para-hydroxybenzoic acids and (ii) oxalic, malonic and succinic acids. Polymeric gels were prepared by adding different wt% of polymer poly(methylmethacrylate) (PMMA) in solutions of respective acids in high dielectric constant organic solvent mixtures of propylene carbonate, ethylene carbonate and dimethylformamide. The highest conductivity in the first of the above group of acids is for o-hydroxy benzoic acid and oxalic acid in the second group of acids. Results have been explained on the basis of "ortho" and/or "inductive" effects which depend upon the relative positions of the substituted hydroxyl (-OH) and carboxyl (-COOH) group or that of the two carboxylic groups.
Solid polymer electrolytes based on polyethylene oxide-silver thiocyanate
(1995) S.S. Sekhon; Gurjinder Singh; S.A. Agnihotry; S. Chandra
The polymer electrolyte films obtained by the addition of silver thiocyanate to polyethylene oxide have been investigated by complex impedance spectroscopy, X-ray diffraction, FTIR, optical microscopy and transference number measurement techniques. It has been observed that complexation takes place mainly in the amorphous region and conductivity of the order of 10-6 S cm-1 has been observed at room temperature. Transference number measurements show that these polymers are mainly anionic conductors. The polymer films have also been found to be sensitive to light. © 1995.
Studies on poly(ethylene oxide)-CuSCN polymer electrolytes
(1993) K.S. Sidhu; S.S. Sekhon; S.A. Hashmi; S. Chandra
The preparation and characterization of polymer electrolytes formed between poly(ethylene oxide) and copper (I) thiocyanate (CuSCN) for various salt concentrations are reported. Differential scanning calorimetry and X-ray diffraction studies show that complexation occurs mainly in the amorphous phase over a wide range of compositions. The a.c. impedance analysis and d.c. polarization measurements show that the polymer complexes have high ionic conductivity. The material is essentially an anionic conductor. © 1993.