Preparation of nano-cerium dioxide and its effect on the thermal decomposition of ammonium perchlorate

Detonation synthesis method was introduced to prepare nano-cerium dioxide. Nano-cerium oxide was obtained by this novel method and its effect on the thermal decomposition of ammonium perchlorate (AP) was studied. X-ray diffraction and transmission electron microscope were used to characterize as-prepared materials. Results showed that as-prepared cerium dioxide was cubic phase and its morphology was nearly spherical. The mean size of as-prepared cerium dioxide particles was 55 nm. Differential scanning calorimetry (DSC) was used to test the effect of as-prepared nano-cerium dioxide on the thermal decomposition of AP. Kissinger method was introduced to calculate activation energy of different specimens according to DSC data. Results indicated that nano-cerium dioxide synthesized by detonation method had catalytic effect on thermal decomposition of AP and could decrease activation energy of AP/CeO₂ mixture.     

Thermal behaviour of CuS (covellite) obtained from copper–thiosulfate system

Thermal behaviour of CuS (covellite) obtained from the Cu(CH₃COO)₂·H₂O and Na₂S₂O₃·5H₂O system, working at different molar ratio (1:6 and 1:4) in presence/absence of NH₄VO₃, was studied. It was established that the presence of vanadium in the system induces a densification of CuS nodules, but do not change the hexagonal CuS structure. It has an important influence in thermal behaviour of copper sulfide CuS obtained also. The morphological characteristics of CuS play an important role in the thermal stability and the stoichiometry of the thermal decompositions. Also, the possibility to obtain copper sulfides with greater cooper content was investigated.     

Pure CuCr2O4 nanoparticles: Synthesis,characterization and their morphological and size effects on the catalytic thermal decomposition of ammonium perchlorate

In the present paper a pure phase of the copper chromite spinel nanoparticles (CuCr₂O₄ SNPs) were synthesized via the sol–gel route using citric acid as a complexing agent. Then, the CuCr₂O₄ SNPs has been characterized by field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). In the next step, with the addition of Cu–Cr–O nanoparticles (NPs), the effects of different parameters such as Cu–Cr–O particle size and the Cu/Cr molar ratios on the thermal behavior of Cu–Cr–O NPs + AP (ammonium perchlorate) mixtures were investigated. As such, the catalytic effect of the Cu–Cr–O NPs for thermal decomposition of AP was evaluated by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). TGA/DSC results showed that the samples with different morphologies exhibited different catalytic activity in different stages of thermal decomposition of AP. Also, in the presence of Cu–Cr–O nanocatalysts, all of the exothermic peaks of AP shifted to a lower temperature, indicating the thermal decomposition of AP was enhanced. Moreover, the heat released (ΔH) in the presence of Cu–Cr–O nanocatalysts was increased to 1490 J g⁻¹.     

Structural organization and thermal properties of crystalline copper(II) <Emphasis Type="Italic">N,N</Emphasis>-<Emphasis Type="Italic">cyclo</Emphasis>-hexamethylenedithiocarbamate: A manifestation of coordination polymerism

The first representative of copper(II) dithiocarbamate complexes with an unusual type of structural organization is synthesized. According to the X-ray diffraction data, the layers of noncentrosymmetric mononuclear [Cu{S₂CN(CH₂)₆}₂] and centrosymmetric binuclear [Cu₂?ub;S₂CN (CH₂)₆?ub;₄] molecules alternate in the crystalline lattice of copper(II) N,N-cyclo-hexamethylenedithiocarbamate. The mononuclear and binuclear forms of the complex are observed in the 2: 1 ratio. The thermal properties of the synthesized compound are studied by thermogravimetry and differential scanning calorimetry. The final product of the thermal destruction of the complex is CuS.     

Synthesis,crystal structure,sensitivity, and effect on thermal decomposition of ammonium perchlorate: an energetic compound Cu(HATZ)(PDA)(H2O)

An energetic coordination compound, Cu(HATZ)(PDA)(H₂O) (HATZ?=?5-aminotetrazole, H₂PDA?=?pyridine-2,6-dicarboxylic acid), has been synthesized and structurally characterized by single crystal X-ray diffraction. Copper(II) was coordinated by two oxygen atoms and nitrogen from PDA, one ring nitrogen of ATZ and one water to form a five-coordinate, distorted square-pyramidal structure. 3-D supramolecular architecture was formed by hydrogen bonding. Thermal decomposition of the compound was examined by DSC and TG-DTG analyses. The kinetic parameters of the first exothermic process of the compound were studied by Kissinger's and Ozawa–Doyle's methods. Sensitivity tests revealed that the compound was insensitive to mechanical stimuli. In addition, the compound was explored as additive to promote thermal decomposition of ammonium perchlorate by differential scanning calorimetry.     

Synthesis and study of lithium triuranate Li2U3O10 · 6H2O

Li₂U₃O₁₀ · 6H₂O crystal hydrate was synthesized by the reaction between synthetic schoepite UO₃ · 2.25H₂O and aqueous lithium nitrate solution under hydrothermal conditions at 200°C. The composition and structure of the obtained compound were established, and its dehydration and thermal decomposition were studied, by chemical analysis, X-ray diffraction, IR spectroscopy, and scanning calorimetry.     

Single-Source Molecular Precursor for Synthesis of Copper Sulfide Nanostructures

As a new precursor, [bis(thiosemicarbazide)copper(II)]chloride; ([Cu(TSC)₂]Cl₂), complex was used in thermal decomposition process for the synthesis of Cu₂S nanocrystals. The steric hindrance of the precursor raises the need of using co-surfactant, therefore oleylamine (C₁₈H₃₇N) and triphenylphosphine (C₁₈H₁₅P) were applied as solvent and surfactant of the reaction. CuS nanocrystals were synthesized via hydrothermal decomposition of [bis(thiosemicarbazide) copper(II)] without any surfactant. The products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy. Synthesized copper sulfide nanostructures have average size of 20–50?nm. Finally, optical properties of the products were examined and investigated by PL spectra.     

Study of the thermal decomposition of historical metal threads

A complex of copper perchlorate coordinated with imidazole Cu(C₃N₂H₄)₄(ClO₄)₂ was synthesized and characterized by X-ray single-crystal diffraction. The complex is centrosymmetric in the monoclinic P2(1)/c space group. The low-temperature molar heat capacities and thermodynamic properties of the complex were studied with adiabatic calorimetry (AC). The thermodynamic functions [H _T–H _298.15] and [S _T–S _298.15] were derived in the temperature range from 80 to 370 K with temperature interval of 5 K. Thermal decomposition behavior of the complex in nitrogen atmosphere was studied by thermogravimetric (TG) analysis and differential scanning calorimetry (DSC). The mechanism of the decomposition was deduced to be the breaking up the two Cl–O bonds of the Cl–O–Cu and the Cu–N bonds of the imidazole rings in succession.     

Syntheses,crystal structures and thermal analyses of two new ionic complexes based on 3,4-diamino-1,2,4-triazole

Two new ionic complexes, (DATr)₂[Li₂(TNR)₂·2H₂O]·2H₂O (1) and (DATr)[Zn(DATr)Cl₃] (2), were synthesized by using 3,4-diamino-1,2,4-triazole (DATr) as outer cation. X-ray single-crystal diffraction analysis revealed that the two complexes crystallize in triclinic and orthorhombic crystal systems, respectively. Differential scanning calorimetry was applied to assess the thermal decomposition behavior and kinetic parameters of decomposition were studied by using Kissinger’s and Ozawa–Doyle’s methods. Furthermore, the critical temperature of thermal explosion and parameters of thermodynamics were obtained.     

硫化铜空心球的合成和生长机理及其在抗肿瘤中的应用

以Cu(NO_3)_2·3H_2O,H_2C_2O_4和Na_2S·9H_2O为原料,利用简易水热方法合成了笼状硫化铜空心球。所得产物用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、透射电子显微镜(TEM)和高分辨透射电子显微镜(HRTEM)进行了表征,并研究了其可能的形成机理。所得CuS空心球具有较高的光热转换性能,在近红外光辐照下,对肿瘤细胞具有明显的光热毒性。     

Thermal studies on solid 1,4-bis(3-carboxy-3-oxo-prop-1-enyl) benzene of lighter trivalent lanthanides

Solid-state compounds of general formula Ln₂L₃·nH₂O, where L represents 1,4-bis(3-carboxy-3-oxo-prop-1-enyl)benzene and Ln = La, Ce, Pr, Nd, Sm, were synthesized. Complexometric titrations with EDTA, thermogravimetry (TG), differential thermal analysis (DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and infrared spectroscopy have been employed to characterize and to study the thermal behavior of these compounds in dynamic air atmosphere. The results led to information about the composition, dehydration, crystallinity, and thermal decomposition of the synthesized compounds.     

Thermal decomposition of basic copper sulphate monohydrate

The thermal decomposition of copper sulphate hydroxide hydrate, (CuO·CuSO₄). 2Cu(OH)₂·H₂O, to copper oxysulphate and CuO was investigated by X-ray phase analysis, IR spectroscopy, complex thermal analysis and electron microscopy. The effect of water vapour and time of treatment on the formation of decomposition products with a large surface area is studied. The strong decrease in specific surface area of the precipitate (from 80 m²/g to 20 m²/g) thermally treated at a temperature above 250°C is associated with the elimination of water having a coordination bond with the Cu²⁺ ion. During this process, the interplanar distances of the crystal lattice of copper sulphate hydroxide hydrate decrease. The time of decomposition of this compound essentially affects the decrease of the specific surface area. When the decomposition proceeds in an atmosphere containing water vapour sintering processes are predominating and the phase obtained has a considerably smaller specific surface area than in cases of decomposition under dry air.     

Preparation and characterization of a new series of solid solutions of Bi1−xYxFeO3 (0 < x < 1) from the thermal decomposition of hexacyanoferrates doped with yttrium

Solid solutions of Bi_1?xY_x[Fe(CN)₆]·4H₂O (0?<?x?<?1) complexes were synthesized and characterized. The crystal structures were refined by Rietveld analysis using X-ray powder diffraction data. The complexes of the series crystallized in the orthorhombic system, space group Cmcm. The gradual decrease in cell volume indicates that the substitution of Bi³⁺ by Y³⁺ was appropriately materialized. The thermal behavior was studied by thermogravimetric and differential thermal analysis. A single phase of perovskite-type Bi_1?xY_xFeO₃ powders was obtained by thermal decomposition of the complexes at about 600 °C. The obtained products were identified and characterized by energy-dispersive spectroscopy, Raman and Fourier transform infrared spectroscopy and powder X-ray diffraction. The size and morphology of the complexes and their thermal decomposition products were evaluated by scanning electron microscopy. Thermal analysis showed that the complexes were good intermediaries for the synthesis of high-purity mixed oxides with a uniform particle size of the order of nanometers. To evaluate the effect of doping with yttrium, electrical transport measurements were performed.

     

Synthesis and study of rare-earth uranogermanates

A series of M^III(HGeUO₆)₃ · 8H₂O rare-earth uranogermanates (M^III = Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er) were prepared by precipitation from solutions under hydrothermal conditions. The compositions and structures of the synthesized compounds were studied, their complete crystallographic and functional similarity were established, and the processes of their dehydration and thermal decomposition were studied on the basis of chemical analysis, X-ray diffraction, IR spectroscopy, and differential scanning calorimetry data.     

Humidity controlled thermal analysis

The low temperature formation of crystalline zinc oxide via thermal decomposition of zinc acetylacetonate monohydrate C₁₀H₁₄O₄Zn·H₂O was studied by humidity controlled thermal analysis. The thermal decomposition was investigated by sample-controlled thermogravimetry (SCTG), thermogravimety combined with evolved gas analysis by mass spectrometry (TG-MS) and simultaneous differential scanning calorimetry and X-ray diffractometry (XRD-DSC). Decomposition of C₁₀H₁₄O₄Zn·H₂O in dry gas by linear heating began with dehydration around 60°C, followed by sublimation and decomposition above 100°C. SCTG was useful because the high-temperature parallel decompositions were inhibited. The decomposition changed with water vapor in the atmosphere. Formation of ZnO was promoted by increasing water vapor and could be synthesized at temperatures below 100°C. XRD-DSC equipped with a humidity generator revealed that C₁₀H₁₄O₄Zn·H₂O decomposed directly to the crystalline ZnO by reacting with water vapor.     

Thermoanalytical investigation of the decomposition course of copper oxysalts

The thermal decomposition of copper nitrate trihydrate (CuNTH); Cu(NO₃)₂·3H₂O was studied up to 600°C by thermogravimetry (TG) and differential thermal analysis (DTA) in a dynamic atmosphere of air. The thermal events occurring throughout the decomposition course were characterized on the basis of spectral analyses using infrared spectroscopy (IR), X-ray diffractometry (XRD) and scanning electron microscopy (SEM). Non-isothermal kinetic parameters were determined. The results showed that the decomposition course involves two main processes, firstly the formation of hydroxy copper nitrate and secondly, the decomposition of this compound to yield CuO. Pathways were suggested that may be involved in the decomposition course.     

A new method of synthesis of BiFeO<Subscript>3</Subscript> prepared by thermal decomposition of Bi[Fe(CN)<Subscript>6</Subscript>]·4H<Subscript>2</Subscript>O

In order to investigate the formation of the multiferroic BiFeO₃, the thermal decomposition of the inorganic complex Bismuth hexacyanoferrate (III) tetrahydrate, Bi[Fe(CN)₆]·4H₂O has been studied. The starting material and the decomposition products were characterized by IR spectroscopy, thermal analysis, laboratory powder X-ray diffraction, and microscopic electron scanning. The crystal structures of these compounds were refined by Rietveld analysis. BiFeO₃ were synthesized by the decomposition thermal method at temperature as low as 600 °C. There is a clear dependence of the type and amount of impurities that are present in the samples with the time and temperature of preparation.     

Synthesis of epoxy-terminated polymers by radical polymerization using α-(t-butylperoxymethyl)styrene as chain transfer agent

Epoxy-terminated polystyrene has been synthesized by radical polymerization using α-(t-butylperoxymethyl) styrene (TPMS) as the chain transfer agent. The chain transfer constants were found to be 0.66 and 0.80 at 60 and 70°C, respectively. The presence of epoxy end groups was confirmed by functional group modification of epoxide to aldehyde by treatment with BF₃.Et₂O. Thermal stability of TPMS was followed by differential scanning calorimetry and iodimetry. Thermal decomposition of TPMS in toluene follows first order kinetics with an activation energy of 23 kcal/mol. © 1996 John Wiley & Sons, Inc.     

Thermal analysis of chemically synthesized polyaniline and effects of thermal aging on conductivity

Thermal characteristics of chemically synthesized polyaniline with various dopants have been studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy, gel-permeation chromatography (GPC), and chemical titration. The HCl-doped polyaniline shows three major weight losses at around 100, 200, and 500°C which are assigned to removal of H₂O and HCl, and decomposition of the polymer, respectively. Thermal aging of the HCl-doped polyaniline performed at 100, 150, and 200°C for various periods of time results in a decrease in conductivity. After the thermal treatments, the polymer can be re-doped with HCl to partially recover the conductivity. However, both the conductivity and the doping level cannot be restored to the level of the original materials owing probably to changes in morphology, crosslinking, or other chemical reactions.     

Synthesis,Crystal Structure,and Properties of Energetic Copper(II) Complex based on 3,5‐Dinitrobenzoic Acid and 1,5‐Diaminotetrazole

Energetic copper(II) complexes based on 3,5‐dinitrobenzoic acid (HDNBA) and 1,5‐diaminotetrazole (DAT), Cu(DNBA)₂(H₂O)₂ ( 1 ) and Cu(DAT)₂(DNBA)₂ ( 2 ) were synthesized and characterized by elemental analysis, IR spectroscopy, single‐crystal and powder X‐ray diffraction. In both complexes, Cu^II was coordinated to a plane tetragon, by four oxygen atoms from two DNBA^– ions and two coordinated H₂O molecules for 1 , and by two oxygen atoms and two nitrogen atoms from different DNBA^– ions and DAT ligands for 2 . Differential scanning calorimetry (DSC) and thermogravimetry (TG) analyses were employed to measure the thermal decomposition processes and non‐isothermal kinetics parameters of the complexes. The thermal decomposition onset temperatures of 1 and 2 are 321 and 177 °C. The apparent activation energies of the first exothermic decomposition peaks of 1 and 2 are 247.2 and 185.2 kJ · mol^–1. Both 1 (35 J, > 360 N) and 2 (12.5 J, > 360 N) are less sensitive than RDX. The catalytic effects on the decomposition of ammonium perchlorate (AP) of 1 and 2 were studied by DSC. All results supported the potential applications of the energetic complexes as additives of solid rocket propellants.