Study of Ion Transport in Lithium Perchlorate-Succinonitrile Plastic Crystalline Electrolyte via Ionic Conductivity and in Situ Cryo-Crystallography

Ion transport mechanism in lithium perchlorate (LiClO4)-succinonitrile (SN), a prototype of plastic crystalline soft matter electrolyte is discussed in the context of solvent configurational isomerism and ion solvation. Contributions of both solvent configurational isomerism and ion solvation are reflected in the activation energy for ion conduction in 0-1 M LiClO4-SN samples. Activation energy due to solvent configurational changes, that is, trans-gauche isomerism is observed to be a function of salt content and decreases in presence of salt (except at high salt concentrations, e.g. 1 M LiClO4-SN). The remnant contribution to activation energy is attributed to ion-association. The X-ray diffraction of single crystals obtained using in situ cryo-crystallography confirms directly the observations of the ionic conductivity measurements. Fourier transform infrared spectroscopy and NMR line width measurements provide additional support to our proposition of ion transport in the prototype plastic crystalline electrolyte.

Structure of nonactin-calcium perchlorate, C40H64O12.Ca(ClO4)2, and a comparative study of metal-nonactin complexes

M r= 975.9, orthorhombic, Pnna, a = 20.262 (3), b= 15.717 (2), c= 15.038 (1)A, V= 4788.97 A 3, z = 4, D x = 1.35 Mg m -3, Cu Kct radiation, 2 = 1.5418 A, /t = 2.79 mm -1, F(000) -= 2072, T = 293 K, R = 0.08, 3335 observed reflections. The molecular structure and the crystal packing are similar to those observed in the nonactin complexes of sodium thiocyanate and potassium thiocyanate. The eight metal-O distances are nearly the same in the potassium complex whereas the four distances involving carbonyl O atoms are shorter than the remaining four involving the tetrahydrofuran-ring O atoms in the Na and the Ca complexes. This observation can be explained in terms of the small ionic radii of Na + and Ca 2+, and leads to a plausible structural rationale for the stronger affinity of nonactin for K + than for the other two metal ions.

Lanthanide perchlorate complexes of 4-nitroquinoline-1-oxide and 5-nitroisoquinoline-2-oxide

Novel complexes of lanthanide perchlorates with 4-nitroquinoline-1-oxide (NQNO) and 5-nitroisoquinoline-2-oxide (NIQNO) have been prepared and characterized. The complexes have the general formulaeLn(NQNO)8(ClO4)3 (whereLn=La-Nd), Ln(NQNO)7(ClO4)3 (whereLn=Gd-Yb),Ln(NIQNO)9(ClO4)3 (whereLn=La-Nd), andLn(NIQNO)7(ClO4)3 (whereLn=Gd-Yb). The IR, proton NMR spectral data indicate the coordination of the N—O group of the ligands to he lanthanide ions.

Thermoanalysis of ammonium perchlorate and sodium nitrate mixture

A binary mixture of ammonium perchlorate-sodium nitrate in molar proportion undergoes partial fusion at 223°C and the transformation of the mixture to sodium perchlorate-ammonium nitrate occurs in the broad endothermic region. The mixture was heated and quenched at various temperatures in a differential thermal analysis assembly. Thermogravimetric analysis, X-ray diffraction, and infrared spectroscopic techniques were used to determine the composition of the quenched sample in order to explain the overall thermal phenomenon. Visual observations of the morphological changes that occur during the course of heating were made using a hot-stage microscope, 30–350°C.

Mechanism of catalytic activity of metal oxides and chromites on ammonium perchlorate pyrolysis

This study investigates the mechanism of action of transition metal chromites on the decomposition of ammonium perchlorate.

Studies on vacuum pyrolysis of ammonium perchlorate and ammonium perchlorate/polystyrene propellant in the presence of transition metal oxides

Vacuum pyrolysis of ammonium perchlorate (AP) and ammonium perchlorate/polystyrene (PS) propellant has been studied by differential thermal analysis (DTA) in order to observe the effect of transition metal oxides on sublimation. Sublimation and decomposition being competitive processes, their proportions depend on the pressure of the pyrolysis chamber. The enthalpies for complete decomposition and complete sublimation are available from the literature and by using these data together with DTA area measurements, the extents of sublimation and decomposition have been calculated for AP and the propellant system. The effect of the metal ions on the extent and rate of sublimation depends on their nature. For AP the extent of sublimation increases with a decrease in particle size. For the propellants the powder sublimes more readily than the bulk material, but in the presence of metal ions the bulk material sublimes more readily than the powder. To substantiate this finding, the effect of MnO2 on AP sublimation as a function of particle size was examined, and it was observed that the extent of sublimation decreases as the particle size decreases.

Mechanistic studies on the pyrolysis and combustion of polystyrene/ammonium perchlorate propellants in the presence of transition metal oxides

The effect of transition metal oxides (Fe2O3, MnO2, Ni2O3 and Co2O3) on polystyrene/ammonium perchlorate propellant systems has been examined. The mechanism of action of the oxides in increasing the burning rate was examined by studying the effect of the oxides on the thermal decomposition and combustion of the oxidizer and the propellant. It has been concluded that one of the mechanisms by which the oxides act is by promoting the charge-transfer process, which is indicated by the enhancement of the electron-transfer process in ammonium perchlorate and by the correlation between the redox potential of the metal ions and the corresponding burning rates of the propellant.

Kinetics and mechanism of anodic oxidation of chlorate ion to perchlorate ion on lead dioxide electrodes

The kinetics and mechanism of anodic oxidation of chlorate ion to perchlorate ion on titanium-substrate lead dioxide electrodes have been investigated experimentally and theoretically. It has been demonstrated that the ionic strength of the solution has a marked effect on the rate of perchlorate formation, whereas the pH of the solution does not influence the reaction rate. Experimental data have also been obtained on the dependence of the reaction rate on the concentration of chlorate ion in the solution at constant ionic strength. With these data, diagnostic kinetic criteria have been deduced and compared with corresponding quantities predicted for various possible mechanisms including double layer effects on electrode kinetics. It has thus been shown that the most probable mechanisms for anodic chlorate oxidation on lead dioxide anodes involve the discharge of a water molecule in a one-electron transfer step to give an adsorbed hydroxyl radical as the rate-determining step for the overall reaction.

Defect Sensitization of Combustion and Thermal Decomposition of Ammonium Perchlorate: Effect of Pelletizing Pressure and Dwell Time

A systematic study was undertaken on the combustion and thermal decomposition of pelletized Ammonium Perchlorate (AP) to investigate the effects of pelletizing pressure and dwell time. At constant pressure, increasing the dwell time results in an increase in the burning rate up to a maximum and thereafter decreases it. The dwell time required for the pellets to have maximum burning rate is a function of pressure. The maximum burning rate is the same for all the pressures used and is also unaffected by increasing, to the range 90-250 μ, the particle size of AP used. In order to explain the occurrence of a maximum in burning rate, pellets were examined for their thermal sensitivities, physical nature and the changes occurring during pelletization with dwell time and pressure. The variations are argued in terms of increasing density, formation of defects such as dislocations leading to an increase in the number of reactive sites, followed by their partial annihilation at longer dwell times due to flow of material during pelletization.

Synthesis and Characterisation of Metal Hydrazine Nitrate, Azide and Perchlorate Complexes

Metal hydrazine nitrate complexes of the type M(N2H4)Nn (NO3)2 where M = Mg, n = 2; M = Mn, Fe, Co, Ni, Zn and Cd and n = 3; metal dihydrazine azide complexes of the type M(N2H4)2 (N3)2 where M = Mg, Co, Ni and Zn; and Mg(N2H4)2 (C1O4)2 have been prepared by dissolving the respective metal powders in the solution of corresponding ammonium salts (NO3, N3 and C1O4) in hydrazine hydrate. These hydrazine complexes were also prepared by the conventional method involving the addition of alcoholic hydrazine hydrate to the aqueous solution of metal salts. The hydrazine complexes have been characterised by chemical analysis, infrared spectra and differential thermal analysis (DTA). Impact sensitivities of hydrazine complexes were determined by the drop weight method. The reactivity of these hydrazine complexes does not change with the method of preparation.

Influence of the electric field on the low-temperature thermal decomposition of ammonium perchlorate/polystyrene propellant

An electric field (100 V/cm at 230°C and 150°C) has been applied to ammonium perchlorate (AP)/polystyrene (PS) propellant mixtures in order to understand the low temperature decomposition behavior of the propellant. The charge-carrying species is anionic in nature at 230°C, which could be ClO4−, but is cationic at 150°C, which could be either NH4+ or H+. These results are parallel to that observed for pure ammonium perchlorate (AP) pellets [1]. The burning rate (r' ) of the propellant was found to follow the same trend as that for the thermal decomposition of the propellant on application of an electric field. At 150°C Image was higher at the −ve electrode than at the +ve electrode, but at 230°C just the opposite was observed. Kinetic studies have confirmed that the decomposition of the orthorhombic AP follows two mechanism corresponding to E = 30 kcal mol−1 (180–230°C) and E = 15 kcal mol−1 (150–180°C).

Role of alloys in the thermal decomposition and combustion of ammonium perchlorate

The participation of aluminum in the decomposition reaction of ammonium perchlorate (AP) is enhanced if magnesium is added—either as a mixture of Al and Mg powders or as an alloy of Mg in Al. The differential thermal analyses of the compositions show a sensitization in the temperatures of decomposition, as well as increase in the heat of reaction. The AP-Mg and Ap-(Mg---Li) alloy pellets also show increased reactivity. The burning rates of AP-(Al-10% Mg) alloy pellets increase with increase in the alloy content, while calorimetric values peak at 40% alloy content. The combustion product gases of AP-40% (Al-10% Mg) alloy contain large quantities of hydrogen.

Thermoanalysis of ammonium perchlorate and sodium nitrate mixture

A binary mixture of ammonium perchlorate-sodium nitrate in molar proportion undergoes partial fusion at 223°C and the transformation of the mixture to sodium perchlorate-ammonium nitrate occurs in the broad endothermic region. The mixture was heated and quenched at various temperatures in a differential thermal analysis assembly. Thermogravimetric analysis, X-ray diffraction, and infrared spectroscopic techniques were used to determine the composition of the quenched sample in order to explain the overall thermal phenomenon. Visual observations of the morphological changes that occur during the course of heating were made using a hot-stage microscope, 30–350°C.

Combustion studies on ammonium perchlorate/trimethylammonium perchlorate mixtures

A study of the burning rates of compressed mixtures of ammonium perchlorate (AP) and trimethylammonium perchlorate (TMAP) has been carried out at ambient pressure. The overall increase in the linear burning rate, showing a maximum at a composition having 80% TMAP, has been discussed in terms of factors such as stoichiometry, presence of faster burning component, and eutectic melt formation. The thermal decomposition studies of the mixtures, using isothermal thermogravimetry and differential thermal analysis techniques, indicate the possibility of eutectic melt formation.

Thermochemistry and lower combustion limit of ammonium perchlorate in presence of methylammonium perchlorates

The heats of combustion of mono-, di-, tri- and tetramethylammonium perchlorates have been determined by bomb calorimetry. The data have been used to explain why the thermal behavior of ammonium perchlorate (AP) is considerably modified in presence of these compounds as shown by differential thermal analysis. Above a particular concentration of methylammonium perchlorate (MAP), AP ignites in a single step around 290°C. The minimum concentration of a MAP (mono-, di-, tri- or tetra-) needed to cause ignition of AP in a single step depends on intramolecular “elemental stoichiometric coefficient” of the mixtures that has the same value regardless of the MAP. Furthermore, the calorimetric values of these mixtures are the same. The heat evolved on ignition of such a composition appears to determine the lower concentration limit of combustion of its mixture with AP.