R. Vijaya Kumar

Isobaric Vapour-Liquid Equilibria in the Allyl Alcohol + 1,2-Dichloro-Ethane System

Isobaric VLE are measured at 200, 500 and 705 mm Hg at ten compositions spread evenly, over the entire liquid mole fraction range, emplying a Swietoslawski-type ebulliometer. The t-x data collected are found to be well represented by the Wilson model.

Activity coefficient and excess gibbs free energy of allyl alcohol with tetrachloroethylene

Abstract Isobaric vapour-liquid equilibrium data are measured at 200, 500 and 705 mm Hg at ten compositions, spread evenly, over the entire mole fraction range. The composition vs. boiling point (x-t) data are found to be well represented by the Wilson model. The optimum Wilson parameters are used to calculate the vapour phase compositions, activity coefficients and the excess Gibbs free energies.

Activity Coefficient and Excess Gibbs Free Energies of Propargyl Alcohol with Trichloroethylene

Abstract Isobaric vapour-liquid equilibrium data are measured at 200, 500 and 707 mm Hg at ten compositions spread evenly over the entire liquid mole fraction range, employing a Swietoslawski type ebulliometer. The liquid phase composition vs. bubble temperature (x-t) data are found to be well represented by Wilson model The optimum Wilson parameters are used to calculate the vapour phase compositions, activity coefficients and the excess Gibbs free energies.

Activity coefficient and excess Gibbs free energies of allyl alcohol with trichloroethylene

Isobaric vapour-liquid equilibrium data have been measured for allyl alcohol and trichlorethylene at 200, 500 and 705 Torr for ten compositions spread evenly over the entire liquid mole fraction range, employing a Swietoslawski-type ebulliometer. The mole fraction composition vs. boiling point data are well represented by the Wilson model. The optimum Wilson parameters are used to calculate the vapour compositions, activity coefficients and the excess Gibbs free energy.

DSC and optical studies on BaO-Li2O-B2O3-CuO glass system

Glasses with composition 15BaO-25Li2O-(60-x)B2O3 -xCuO (x= 0, 0.2, 0.4, 0.6, 0.8 and 1 mol%) were prepared by the conventional melt quenching technique. These glasses were characterized using X-ray diffraction (XRD), differential scanning calorimetry (DSC) and density measurements. Optical absorption studies were carried out as a function of copper ion concentration. The optical absorption spectra of studied glasses containing copper oxide exhibit a single broad band around 761nm which has been assigned to the 2B1g→2B2g transition. From these studies, the variations in the values of glass transition temperature (Tg) have been observed. The fundamental absorption edge has been determined from the optical absorption spectra. The values of optical band gap and Urbach energy were determined with increase in concentration of CuO. The variations in density, glass transition temperature, optical band gap and Urbach energy with CuO content have been discussed in terms of changes in the glass structure. The analys...

Physical and optical studies of BaO-TeO2-TiO2-B2O3 glasses containing Cu2+ transition metal ion

Glasses with the composition xBaO-(30-x) TeO2-10TiO2-59B2O3-1CuO (where x = 10, 15, 20 and 25 mole %) were prepared by melt quenching technique. The XRD studies were made on these glass samples at room temperature. The amorphous nature of the glass samples was confirmed from the XRD patterns. The physical parameters such as density (ρ), molar volume (Vm), average boron-boron separation (dB-B) and oxygen packing density (OPD) were calculated. The change in density and molar volume has been investigated in terms of the variation of BaO in the glass composition. The optical absorption spectra have been recorded at room temperature. The values of optical band gap have been estimated from the ASF and Tauc’s methods. Both Tauc’s and ASF methods have been showing progressively increasing indirect optical band gap values with the increase of BaO concentrations.Glasses with the composition xBaO-(30-x) TeO2-10TiO2-59B2O3-1CuO (where x = 10, 15, 20 and 25 mole %) were prepared by melt quenching technique. The XRD studies were made on these glass samples at room temperature. The amorphous nature of the glass samples was confirmed from the XRD patterns. The physical parameters such as density (ρ), molar volume (Vm), average boron-boron separation (dB-B) and oxygen packing density (OPD) were calculated. The change in density and molar volume has been investigated in terms of the variation of BaO in the glass composition. The optical absorption spectra have been recorded at room temperature. The values of optical band gap have been estimated from the ASF and Tauc’s methods. Both Tauc’s and ASF methods have been showing progressively increasing indirect optical band gap values with the increase of BaO concentrations.

Electron paramagnetic resonance spectra of copper ion doped lithium barium borate glasses

Glasses with composition 25Li2O-15BaO- (60-x) B2O3- x CuO (where x=0, 0.2, 0.4, 0.6, 0.8 and 1.0 mol %) were prepared by the conventional melt quenching technique. These glasses were characterized using X-ray diffraction (XRD). Electron paramagnetic resonance spectra of prepared glasses have been studied. The EPR spectrum consists of four hyperfine lines characteristic of Cu2+ ions. From the observed spectra the spin-Hamiltonian parameters have been evaluated. The values of spin-Hamiltonian parameters indicate that the Cu2+ ions in the studied glasses were present in octahedral coordination with a strong tetragonal distortion. The molecular orbital coefficients have been evaluated.Glasses with composition 25Li2O-15BaO- (60-x) B2O3- x CuO (where x=0, 0.2, 0.4, 0.6, 0.8 and 1.0 mol %) were prepared by the conventional melt quenching technique. These glasses were characterized using X-ray diffraction (XRD). Electron paramagnetic resonance spectra of prepared glasses have been studied. The EPR spectrum consists of four hyperfine lines characteristic of Cu2+ ions. From the observed spectra the spin-Hamiltonian parameters have been evaluated. The values of spin-Hamiltonian parameters indicate that the Cu2+ ions in the studied glasses were present in octahedral coordination with a strong tetragonal distortion. The molecular orbital coefficients have been evaluated.

Physical and optical absorption studies of Fe3+ - ions doped lithium borate glasses containing certain alkaline earths

Iron ion doped lithium borate glasses with the composition 15RO-25Li2O-59B2O3-1Fe2O3 (where R= Ca, Sr and Ba) have been prepared by the conventional melt quenching technique and characterized to investigate the physical and optical properties using XRD, density, molar volume and UV-Visible spectroscopy. The optical absorption spectra exhibit a band at around 460 nm which is assigned to 6A1g(S) → 4Eg (G) of Fe3+ ions with distorted octahedral symmetry. From ultraviolet absorption edges, the optical band gap and Urbach energies have been evaluated. The effect of alkaline earths on these properties is discussed.

FTIR and Raman studies on 25Bi2O3-(75-x)B2O3-xBaO glasses

Raman and Infrared spectroscopies have been employed to investigate the 25Bi2O3-(75-x)B2O3-xBaO glasses in order to obtain information about the competitive role of Bi2O3 and B2O3 in the formation of glass network. FTIR and Raman spectra show that these glasses are made up of [BO3], [BO4], [BiO3] pyramidal and [BiO6] octahedral units.

Spectroscopic studies of xLi2O-(40-x)Bi2O3-20CdO-40B2O3 Glasses

Glasses with composition xLi2O-(40- x)Bi2O3-20CdO-40B2O3 where (0 ≤ x ≤ 40) have been prepared using melt quench technique. Optical absorption spectra of the pure glasses reveled that the cutoff wave length decreases and optical band gap (Eopt) and Urbach energy (ΔE) increases with increase in Li2O content. The Eopt values of these glasses are found to be in the range 2.818-3.258 eV where as the values of ΔE are in the range 0.21-0.33 eV. Raman and infrared spectroscopies have been employed to investigate these glasses in order to obtain information about the competitive role of Bi2O3 and B2O3 in the formation of glass network. IR and Raman spectra show that these glasses are made up of [BO3], [BO4], [BiO3] and [BiO6] units. The formation of Cd in tetrahedral co-ordination was not observed.