L.W. Collins

Bio: L.W. Collins is an academic researcher from United States Department of Energy. The author has contributed to research in topics: Thermal decomposition & Oxide. The author has an hindex of 1, co-authored 1 publications receiving 10 citations.

The catalytic decomposition of potassium perchlorate

Abstract: The thermal decomposition of potassium perchlorate in the presence of various metal oxides was investigated by thermogravimetry and by isothermal weight loss techniques. The effect of metal oxide concentration on the temperature of initial deflection, Ti, of thermogravimetry curves of metal oxide/potassium perchlorate mixtures was determined. The Arrhenius parameters were also tabulated to demonstrate the effect of metal oxide concentration on the rate of decomposition of the potassium perchlorate.

Mono, di and trinuclear photo-luminescent cadmium(II) complexes with N2O and N2O2 donor salicylidimine Schiff bases: Synthesis, structure and self assembly

Abstract: Four new octahedral cadmium(II) complexes, [(Cd)(L1)(HL1)](ClO4) (1), [Cd2(L2)2(SCN)2(CH3OH)2] (2), [(CdL3)3(μ-1,1,1-OH)](ClO4)2 (3) and [Cd2(L4)2(SCN)(NO3)] (4) have been synthesized using four Schiff bases, HL1, HL2, HL3 and HL4, (where HL1 = 2-(2-(ethylamino)ethyliminomethyl)phenol, HL2 = 2-(2-(dimethylamino)ethyliminomethyl)-4-bromophenol, HL3 = 2-(2-(diethylamino)ethyliminomethyl)-6-methoxyphenol and HL4 = 2-(2-(ethylamino)ethyliminomethyl)-6-methoxyphenol). All four complexes have been characterized by elemental and spectral analysis and structures have been confirmed by single crystal X-ray diffraction studies. Complex 1 is a mononuclear cationic bis-ligand complex. Complex 2 features a double end-to-end thiocyanate bridged dinuclear cadmium(II) complex. Complex 3 has a partial cubane [Cd3O4] core in which three [CdL3] subunits are interconnected through two types of oxygen bridges afforded by phenoxo oxygen atoms of ligands and a central hydroxo group. Complex 4 has a double phenoxo bridged dinuclear structure. Supramolecular interactions in all four complexes were also explored. All four complexes show fluorescence.

Ignition of Nanoscale Titanium/Potassium Perchlorate Pyrotechnic Powder: Reaction Mechanism Study

Abstract: The reaction mechanism and ignition characteristics of the pyrotechnic composite of titanium nanoparticles and micron-sized potassium perchlorate was investigated under rapid heating conditions (∼5 × 105 K/s) by temperature jump (T-Jump) time-of-flight mass spectrometry. X-ray photoelectron spectroscopy surface analysis and transmission electron microscopy (TEM) characterization of titanium nanoparticles show a reactive oxide layer (∼6 nm) composed of amorphous TiO2 and roughly 20% crystalline TiN and titanium oxynitride. The T-Jump and thermogravimetric analysis reveals the oxide layer to be responsible for catalysis of oxygen release from KClO4, resulting in ignition temperatures as low as 720 K in atmospheric pressure argon. Fast and slow in situ heating TEM corroborate the findings of oxygen atmosphere ignition characteristics, which illustrate KClO4 melting and coating of titanium nanoparticles immediately before oxidizer decomposition and titanium oxidation. Unlike aluminum, which has been shown to ...

The DSC studies on the phase transition, decomposition and melting of potassium perchlorate with additives

Abstract: It has been shown that the addition of metal oxide to potassium perchlorate gives rise to change in the thermochemical behavior of the potassium perchlorate. Some investigations on the particle sizes and materials were examined, and given data for choosing optimum weight percentage to achieve certain firing characteristics of hot-wire pyrotechnic devices. In this study, the additives (Al 2 O 3 and Fe 2 O 3 ) are found to have no effect on the crystal structure transformation, the fusion of KClO 4 and the fusion of KCl. But both of the metal oxide powders exhibited a remarkable acceleration effect on the decomposition of KClO 4 , especially Fe 2 O 3 does.

Catalytic effects of magnesium chromite spinel on the decomposition of lanthanum oxalate

Abstract: A study on the thermal decomposition of mixtures of lanthanum oxalate hydrate and magnesium chromite spinel, MgCr2O4 of different molar ratios has been carried out employing thermogravimetry, differential thermal analysis, chemical analysis, infrared spectroscopy and X-ray diffraction analysis. It is evident from the data that lanthanum oxalate in the presence of mixed oxide starts to decompose at a temperature higher than the pure salt. The results reveal that chromium oxide has a retarding effect on the decomposition rate and addition of magnesium oxide leads to an observable increase in the catalytic behaviour of Cr2O3 towards the decomposition below 440 °C, above which it increases significantly with increasing percentage of MgCr2O4. The induced defects during the formation of solid solution alters the conductive properties of the oxide, due to generation of more holes within the catalyst, consequently increasing its, activity towards decomposition. The kinetic and thermogravimetric parameters are evaluated in the light of D3 mechanism. The reaction occurs through three different stages and the rate constant, k is found to follow the order: stage I > stage II stage III and LO1>LO2>LO3 (653–713 K), LO1

Thermal ignition of titanium based pyrotechnics

Abstract: The thermal ignition of titanium-based pyrotechnics was shown to be controlled by titanium oxides, which encapsulate the metal particles. As the titanium powder was heated, the oxide coating dissolved into the bulk metal to generate a reactive surface. The surface was reoxidized immediately by oxygen gas from the surrounding atmosphere but with insufficient heat generation for sustained combustion. Ignition was kinetically determined by the rate of dissolution of the oxide coating versus the rate of reoxidation.