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Latha D.M.,Andhra University | Pisipati V.G.K.M.,Andhra University | Prasad P.V.D.,Hindu College
Molecular Crystals and Liquid Crystals | Year: 2010

Different thermodynamic parameters are estimated from volume expansion coefficient, α, for a number of N-(p-n-alkoxy benzylidene)-p-n-alkyl anilines, nO.m compounds in isotropic phase at TIN+5°C. The parameters like intermolecular free length, Lf, and molecular radius, Mr, are also computed from density, sound velocity, and refractive index for these nO.m compounds for which the data are available in the literature. The results are discussed in light of these parameters' variations with temperature in a particular phase in a liquid-crystal molecule and in a homologous series. The nature of molecular free length and molecular radius is analyzed and discussed with respect to the different expressions used for the estimation of these parameters and the reasons for their deviations in values from one method to the other. Copyright © Taylor & Francis Group, LLC.

Rani R.,Electroceramics Research Laboratory | Rani R.,Thapar University | Juneja J.K.,Hindu College | Singh S.,GVM Girls College | And 2 more authors.
Journal of Magnetism and Magnetic Materials | Year: 2013

Magnetoelectric composites of nickel zinc ferrite (NZF) and La substituted lead zirconate titanate (PLZT) having representative formula 0.1Ni 0.8Zn 0.2Fe 2O 4-0.9Pb 1-3x/2La xZr 0.65Ti 0.35O 3 (x=0, 0.01, 0.02 and 0.03) were synthesized by a conventional solid state route. X-ray diffraction analysis was carried out to confirm the coexistence of individual phases. Scanning electron microscope micrographs were taken for microstructural study of the samples. Dielectric properties were studied as a function of temperature and frequency. To study ferroelectric and magnetic ordering in composite samples, P-E and M-H hysteresis loops were recorded respectively. M-H hysteresis loops were taken for electrically poled and unpoled samples to confirm magnetoelectric coupling between the two phases (NZF and PLZT). La substitution results in significant improvement in dielectric, ferroelectric and piezoelectric properties of composite samples. © 2012 Elsevier B.V. All rights reserved.

Sharma V.K.,iversity | Bhagour S.,iversity | Solanki S.,iversity | Sharma D.,Hindu College
Journal of Chemical Thermodynamics | Year: 2014

The excess heat capacities, (CPE) and (C PE)ijk (calculated from the measured molar heat capacities, Cp data) of binary 1-ethyl-3-methylimidazolium tetrafluoroborate (i) + pyrrolidin-2-one or 1-methylpyrrolidin-2-one or pyridine (j); pyrrolidin-2-one (i) + pyridine (j) and ternary 1-ethyl-3- methylimidazolium tetrafluoroborate (i) + pyrrolidin-2-one or 1-methylpyrrolidin-2-one (j) + pyridine (k) mixtures have been measured as a function of composition at T = (293.15, 298.15, 303.15 and 308.15) K and 0.1 MPa using micro differential scanning calorimeter. The (CP E)ijk values for the present ternary mixtures are positive over entire range of composition. The CPE and (CPE) ijk data have been fitted to Redlich-Kister equation to compute binary and ternary adjustable parameters along with their standard deviations. The topology of the constituent molecules (Graph theory) has been utilized to obtain the expressions that describe well the (CPE) and (CPE)ijk data of the present mixtures. It has been observed that Graph theory describes well the (CPE) and (CPE)ijk data of the binary as well as ternary mixtures. © 2014 Elsevier Ltd. All rights reserved.

Sharma V.K.,Md University | Dua R.,Md University | Sharma D.,Hindu College
Journal of Chemical Thermodynamics | Year: 2014

Densities and speeds of sound data for ternary o-chlorotoluene (i) + tetrahydropyran (j) + N-methylformamide or N,N-dimethylformamide or cyclohexane (k) and their sub-binary o-chlorotoluene or (tetrahydropyran + cyclohexane) mixtures have been measured at temperatures (298.15, 303.15, 308.15) K and 0.1 MPa. The excess molar volumes, VijkE, VE and excess isentropic compressibilities, (κSE)ijk, κSE for ternary and binary mixtures respectively have been determined from the experimental densities, speeds of sound values and fitted to Redlich-Kister equation to calculate ternary and binary adjustable parameters along with standard deviations. The excess properties, VijkE and (κSE)ijk have been tested in terms of (i) Graph; and (ii) Prigogine-Flory-Patterson (PFP) theories. © 2014 Elsevier Ltd. All rights reserved.

Pisipati V.G.K.M.,Koneru Lakshmaiah College of Engineering | Madhavi Latha D.,Koneru Lakshmaiah College of Engineering | Datta Prasad P.V.,Hindu College | Padmaja Rani G.,Jawaharlal Nehru Technological University Kakinada
Journal of Molecular Liquids | Year: 2012

The effective geometry parameter, α g = n o/n e is utilized to calculate the order parameter in a number of liquid crystals of different homologous series. The results are compared with those calculated using the standard techniques of molecular polarizability and birefringence. The effective geometry parameter's, α g influence on the deflection of the light by the liquid crystal compounds is also studied. © 2012 Elsevier B.V.

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