Thermal decomposition of ammonium perchlorate single crystals

The thermal decomposition of large single crystals of pure ammonium perchlorate and ammonium perchlorate doped with Ba2⁺ or SO^2?₄ ions has been investigated over the temperature range 220–290°C. Comparative studies were also made with compressed pellets of the pure powder and with small single crystals containing macroscopic flaws. The kinetic results were analyzed using a computer technique which permits a very detailed examination of various kinetic models. This reveals that the “induction period” (α < ～ 0.01) is very complex and comprises a desorption step, a linear process, an exponential process, and the beginnings of an Avrami process. The latter three processes are identified with (i) the inward growth of rapidly formed surface nuclei, (ii) “branching” of surface nuclei, and (iii) nucleation in the bulk crystal. Kinetic parameters are obtained for these three processes and also for the growth of nuclei in the bulk crystal. This model fits the kinetic data over the complete range of α(0–1), or 1 × 10^?5 < α < 1 if the desorption step is not included. The mechanism of the reaction and possible effects on this of Ba²⁺ and SO^2?₄ doping are discussed briefly.     

Direct current conduction in ammonium perchlorate single crystals

The dc electrical conductivity of pure and doped ammonium perchlorate (AP) has been studied in two different crystal orientations, with the electric field applied perpendicularly to either (001) or (210) planes. The conductivity along the direction of the c axis was found to be lower than that normal to (210) by a factor of 5 to 10. The dc electrical conductivity of AP is decreased by Pb²⁺ ions but increased by SO^2?₄ and CrO^2?₄ ions. The conductivity of pure AP and of Pb²⁺-doped AP displays two regions with activation energies for conduction of 0.56 and 0.87 eV, respectively. The conductivity of the anion-doped crystals has a single activation energy, 0.66 eV for SO^2?₄ and 0.72 eV for CrO^2?₄. Exposure to ammonia enhances the conductivity of pure AP. A proton conduction mechanism is proposed that takes due regard of the structure of AP. The effect of the various additives on the conductivity are attributed to their influences on the formation of charge-carrying protons.     

Thermal decomposition of ammonium perchlorate

This review represents an attempt to summarize literature data on thermal decomposition of ammonium perchlorate. The mechanism of thermal decomposition and various factors which influence on the thermal decomposition of ammonium perchlorate are discussed.     

Kinetics of ammonium perchlorate decomposition

The kinetic law of ammonium perchlorate decomposition in the presence and absence of metal oxides has been studied. Sublimation has also been considered from the kinetic point of view.

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Thermal decomposition of doped ammonium perchlorate

Isothermal decomposition of orthorhombic ammonium perchlorate (AP) has been studied as a function of concentration of the dopants, SO ₄ ^2– and PO ₄ ^3– . In either case, the rate of decomposition passes through a maximum as the dopant concentration increases. Activation energy of the decomposition process remains unaltered by doping. The results are interpreted in terms of electron transfer mechanism.

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Zusammenfassung Die isotherme Zersetzung von orthorhombischen Ammoniumperchlorat (AP) wurde in Abhängigkeit von der Konzentration der Dopanten SO ₄ ^2– und PO ₄ ^3– untersucht. In jedem Falle geht die Geschwindigkeit der Zersetzung mit steigender Dopantenkonzentration durch ein Maximum. Die Aktivierungsenergie des Zersetzungsprozesses wird durch dopen nicht verändert. Die Ergebnisse werden auf einem Elektronentransfer-Mechanismus basierend interpretiert.

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The author is thankful to Dr. V. R. Pai Verneker of Indian Institute of Science, Bangalore, for stimulating discussions.     

The thermal decomposition of doped ammonium perchlorate

The thermal decomposition of ammonium perchlorate doped with Cu²⁺, Mn²⁺, Co²⁺ and Fe³⁺ (with and without H⁺) was studied using DTA and TG. Small concentrations of these ions inhibit the decomposition by eliminating the first exothermic peak. At higher concentrations, a catalyzed decomposition is observed. Either the influence of the doping ions on the mechanism of the thermal decomposition is different from that of added oxides or a modification of the electron transfer mechanism is needed.     

Effect of tetramethylammonium perchlorate on ammonium perchlorate and propellant decomposition

The thermal decomposition of ammonium perchlorate (AP) is considerably modified when it is cocrystallized or mixed with small amounts of tetramethyl- ammonium perchlorate. The decomposition is sensitized when tetramethylphosphonium perchlorate is added to AP. The effect on the isothermal decomposition of AP when it is mixed with tetramethylammonium perchlorate, appears to be similar to that of AP-based composite propellant having the same mixed AP composition.     

CuO nanocrystals in thermal decomposition of ammonium perchlorate

CuO nanocrystals of different surface areas were prepared. All samples were characterized by X-ray diffraction, transition electron microscope, thermogravimetry, Brunauer-Emmett-Teller technique, Fourier transform infrared spectroscopy, and Raman spectroscopy. CuO nanocrystals showed a stable monoclinic structure. With increasing surface areas, the surface hydration became significant, which is followed by shifts in infrared frequencies and Raman phonon modes. CuO nanocrystals were explored as an additive to catalytic decomposition of ammonium perchlorate (AP). AP decomposition underwent a two-stage process. Addition of CuO nanocrystals led to a downshift of high-temperature stage towards lower temperatures.     

Photothermochemical process in ammonium perchlorate crystals: II

The influence of phase transition (PT) on the process of thermal development of a latent image arising after X-ray and uv irradiation of ammonium perchlorate (AP) crystals has been studied. Despite the production of a large number of new dislocations accompanying PT, it essentially does not influence the thermal development: The developed image does not smear at PT, remaining as clear as before it. By comparing mirror-symmetric surfaces of cleavage planes of AP crystals, it has been shown that at doses of X-ray and uv irradiation sufficient for obtaining an image, no production of new dislocations was observed in AP crystals. It is suggested that latent image arises due to formation during irradiation of chlorine oxidic products of radiolysis: ClO₃, ClO₂, and ClO as well as the corresponding ions ClO^?, ClO^?₂, and ClO^?₃, i.e., initiators of AP low-temperature decomposition.     

Photothermochemical process in ammonium perchlorate crystals: I

It is shown that during uv irradiation of ammonium perchlorate (AP) crystals through an opaque stencil a latent photographic image of the stencil arises in their volume. This image can be developed on a crystal surface by heating at 230°C. The induction period of low-temperature decomposition (LTD) of polycrystalline AP depends linearly on the dose of preliminary uv irradiation: τ_LTD = τ₀ ? A log (I · t_irr). It is suggested that the mechanism of latent image formation consists of generation in the crystal volume of the chlorine oxidic products of AP photolysis—mainly ClO^?₃ ions. Based on these considerations one is able to explain in a consistent way all the experimental data obtained: τ_LTD dependence on dose, dependence of thermal development time on the concentration of proton-active additives, dependence of the image optical density on crystal depth, etc.     

Effect of electric field on ammonium perchlorate decomposition

A novel method of detecting the charge-carrying species in inorganic decomposable salts is described. In ammonium perchlorate it is observed that the charge-carrying species at temperatures 150 and 230°C are oppositely charged; i.e., they are negatively charged (ClO^?₄ ions) at 230°C and positively charged (H⁺ or NH⁺₄) at 150°C.     

Radiation effects on thermal decomposition of ammonium perchlorate

Thermal decomposition of -irradiated (dose: 0–3.6 MGy) ammonium perchlorate was followed. The dynamic heating (range: 100–220 °C) and IR spectral measurements were carried out simultaneously. Temperature and dose brought a lowering in peak intensity of NH ₄ ⁺ and C10 ₄ ^– ions. Radiolytic products C10₃ and NH₃ are considered to initiate the decomposition process.     

Thermal decomposition of ammonium perchlorate based mixture with fullerenes

The effects of fullerenes, including fellerene soot (FS), extracted fullerene soot (EFS) and pure C₆₀ on the thermal decomposition of ammonium perchlorate (AP) compared with traditional carbon black (CB) catalyst has been studied by employing thermogravimetry (TG), differential thermal analysis (DTA), infrared spectroscopy (IR) and ignition temperature experiments. The results showed that the addition of CB and FS to AP reduced the activation energy as well as the temperature at maximum decomposition rate, but that of EFS and pure C₆₀ had little effect on the thermal decomposition of AP, and among all catalysts, FS was the best one.     

Thermal decomposition properties of double-base propellant and ammonium perchlorate

The thermal decomposition properties and the heat of combustion (ΔH) of samples with different ammonium perchlorate (AP)/double base propellant (DB) mass ratios under argon atmosphere were studied by the thermogravimetry–differential scanning calorimetry–mass spectrometry–Fourier transform infrared spectroscopy (TG–DSC–MS–FTIR) and automatic calorimeter method. The results show that decomposition process of AP/DB samples in negative and zero oxygen balance (OB) is different from that in positive OB. With the increasing of AP in the AP/DB samples, the decomposition of the samples becomes more and more severe. When the OB of the samples is positive, the phenomenon of deflagration or explosion could be observed in the decomposition process. The sample with OB = 0 has the greatest heat of combustion.     

Thermal decomposition of ammonium perchlorate in the presence of bimetallic additives

The catalytic activity of the thermolysis products of double complex compounds in the decomposition reaction of ammonium perchlorate was studied. The products used are C_1.4N_1.6H₃CoFe (I), C₆N₈Co₄Fe₃ (II), O₁₁Co₄Fe₃ (III), O_8.5(CN)_0.3Cu₃Fe₂ (IV), and reactive CuO. All active phases decrease the temperature of complete decomposition of NH₄ClO₄, and the order of temperature decreasing is the following: I ≈ II (120 °C) > IV > III (80 °C) ? CuO.     

Effect of aluminum morphology on thermal decomposition of ammonium perchlorate

Journal of Thermal Analysis and Calorimetry - In this paper, two kinds of flake aluminum powder are prepared by bidirectional rotation mill using the spherical aluminum powder (Al-1) as raw...     

Insight into the catalytic thermal decomposition mechanism of ammonium perchlorate

Journal of Thermal Analysis and Calorimetry -     

Effects of different additives on the thermal decomposition of ammonium perchlorate

IR spectral investigations on ammonium perchlorate (AP) in the presence of varying amounts of ammonium permanganate (APm) and 2% by weight of different rare earth oxide additives were made over the temperature range 25–290°. Heating and spectral scanning were done simultaneously and the peak intensity was presumed to be proportional to the amount of undecomposed AP. Presence of 10% APm lowered the temperature of AP decomposition from 200 to 110° and increased the rate by several folds. Mixed oxide produced as a result of deflagration of APm are considered catalyzing the process. In the presence of rare earth oxides additives, the NH ₄ ⁺ stretching peak intensity decreased considerably, the extent followed the trend Gd₂O₃ > MnO₂ > Nd₂O₃ > Pr₂O₃ > Dy₂O₃ > Y₂O₃ > La₂O₃ > virgin AP. An electron transfer mechanism is envisaged to explain the results.     

Thermal decomposition of ammonium perchlorate activated via addition of NiO nanocrystals

This work reported on the thermal decomposition of ammonium perchlorate activated by addition of NiO nanocrystals with different surface areas. NiO samples were characterized by X-ray diffraction (XRD), transition electron microscope (TEM), Brunauer-Emmett-Teller (BET) technique, Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. With increasing annealing temperature, the surface areas of NiO samples reduced from 108.6 to 0.9 m² g⁻¹. The catalytic activities of NiO nanocrystals on the thermal decomposition of ammonium perchlorate were investigated by thermogravimetric analysis (TG) coupled with differential thermal analysis (DTA). With addition of NiO nanocrystals, thermal decomposition temperature of AP decreased greatly. Larger surface areas of NiO nanocrystals promoted the thermal decomposition of AP.     

Comparative DFT study of crystalline ammonium perchlorate and ammonium dinitramide

The electronic structure, vibrational properties, absorption spectra, and thermodynamic properties of crystalline ammonium perchlorate (AP) and ammonium dinitramide (ADN) have been comparatively studied using density functional theory in the local density approximation. The results shows that the p states for the two solids play a very important role in their chemical reaction. From the low frequency to high frequency region, ADN has more motion modes for the vibrational frequencies than AP. The absorption spectra of AP and ADN display a few, strong bands in the fundamental absorption region. The thermodynamic properties show that ADN is easier to decompose than AP as the temperature increases.