Pyrolysis and combustion of α-cellulose: effect of dihydrazinium phosphate (N2H5)2HPO4

A strip of Whatman filter paper (α-cellulose) dipped in an aqueous solution of dihydrazinium phosphate, (N₂H₅)₂HPO₄(DHP), and dried, carbonized without flame when ignited. The observed flame retardancy of DHP on α-cellulose has been studied using TG, DTA and mass spectrometry. Dihydrazinium phosphate appears to catalyze the dehydration of α-cellulose, minimizing the depolymerization which produces flammable tars, with the formation of water and char. Flame retardancy of DHP is compared with that of diammonium phosphate and phosphoric acid.     

Effect of Sm3+ concentration on electroluminescence excitation mechanism in (Zn,Cd) S phosphors

(Zn, Cd)S phosphors activated with varying concentrations of Sm³⁺ have been prepared in argon atmosphere, and their voltage dependence of EL-brightness, current-voltage characteristics and SEM measurements have been carried out. The nature of variation of EL-brightness with voltage is found to depend on Sm³⁺ concentration. The result is interpreted as an effect of increase in number and effectiveness of Mott-Schottky type potential barriers which probably exist at the grain boundaries.     

Study of excess volume of mixing in mixed salt solution: The ternary systems involving tetramethylammonium bromide, alkali bromides and D2O at 298-15 K

The densities of solutions of (CH₃)₄NBr + LiBr + D₂O, (CH₃)₄NBr + KBr + D₂O and (CH₃)₄NBr + CsBr + D₂O were determined at 298.15K at a fixed ionic strength of 4.0M and varying salt mole-fractions. Some results were also obtained at ionic strengths 2.0 and 3.0 for equimolar mixtures of the salts. The mean apparent molar volumes were calculated and used to obtain excess volumes of mixing. The results were compared with similar data in the literature and interpreted in terms of ion-ion interactions and Friedman’s volume interaction parameters.     

γ-Radiolysis of isobutanol and nitrate in aqueous solution

Radiolysis of isobutanol-nitrate aqueous solutions has been investigated in both aerated and deoxygenated solutions. Nitrate acts as a good scavenger for hydrated electrons. It gets reduced to nitrite during radiolysis. Alcohol, on the other hand, is used as a hydroxyl radical scavenger leading to the formation of aldehyde as the stable product. Nitrite, aldehyde and hydrogen peroxide formed as the stable products have been estimated in each system. Concentrations of both species (nitrate and alcohol) in the aqueous solution affect the yield of the products significantly. The observed G-values of the different products are accounted for by the mechanism proposed.     

Study of structural and electronic transport properties of Ce-doped LaMnO3

The structural and electronic transport properties of La_1−x Ce _x MnO₃ (x=0.0–1.0) have been studied. All the samples exhibit orthorhombic crystal symmetry and the unit cell volume decreases with Ce doping. They also make a metal-insulator transition (MIT) and transition temperature increases with increase in Ce concentration up to 50% doping. The system La_0.5Ce_0.5MnO₃ also exhibits MIT instead of charge-ordered state as observed in the hole doped systems of the same composition.     

Synthesis and physicochemical studies on Ni(II) complex of 2-hydroxy-acetophenonethiosemicarbazone and its square-planar adducts with nitrogen donors

NiL₂X₂ complex and its adducts of the type NiL (base), where L is a 2-hydroxy-acetophenonethiosemicarbazone, X=C1 and base (ammonia, pyridine, aniline,o-, m-, p-toluidine and water) have been synthesized and characterised by analysis, magnetic moments, electronic and infrared spectra.