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Some transition metal nitrate complexes with hexamethylenetetramine

Part LV. Preparation, X-ray crystallography and thermal decomposition

Journal of Thermal Analysis and Calorimetry
Authors: G. Singh, B. Baranwal, I. Kapoor, D. Kumar, C. Singh, and R. Fröhlich

Abstract  

Three hexamethylenetetramine (HMTA) metal nitrate complexes such as [M(H2O)4(H2O-HMTA)2](NO3)·4H2O (where M=Co, Ni and Zn) have been prepared and characterized by X-ray crystallography. Their thermal decomposition have been studied by using dynamic, isothermal thermogravimery (TG) and differential thermal analysis (DTA). Kinetics of thermal decomposition was undertaken by applying model-fitting as well as isoconversional methods. The possible pathways of thermolysis have also been proposed. Ignition delay measurements have been carried out to investigate the response of these complexes under condition of rapid heating.

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(NiFe 2 O 4 , LiMn 2 O 4 , and CoFe 2 O 4 ) [ 6 , 7 ]. The PVA-based synthesis methods consist usually of one-step thermal treatment of the metal nitrate–PVA solution, or of gelation, followed by calcinations. These methods allow the obtaining

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SiO 2 matrix, of some particular precursors, coordination compounds of the involved M II and M III cations with dicarboxylate ligands obtained in the redox reaction between metal nitrates and 1,3-propanediol. In reaction with M II (NO 3 ) 2 or M

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Journal of Thermal Analysis and Calorimetry
Authors: A. Małecki, R. Gajerski, S. Łabuś, B. Prochowska-Klisch, and K. Wojciechowski

Abstract  

A series of six nitrates(V) hydrates of 4d-metals as well as mercury and cadmium thermal decomposition was examined by DTA, TG and EGA techniques. It was found that thermal decomposition of d-metals nitrate(V) hydrates proceeds in three stages: partial dehydration, oxo-nitrates and hydroxide nitrates formation and metal oxides formation. General chemical equations for all decomposition stages were proposed. It was found that dehydration of hydrated salts is accompanied by partial decomposition of nitrate(V) groups.

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Abstract  

Montmorillonite-supported iron(III) nitrate and copper(II) nitrate reagents, and other supported metal nitrates prepared in the same way, were investigated by thermal and X-ray powder diffraction methods. The metal nitrates are present on the support in the form of crystalline hydrate and not as acetone solvate as supposed earlier. Thermal decomposition of metal nitrates that are active in model reactions proceeds in a different way from that of the practically inactive nitrates. In the former case, water release and nitrate decomposition itself are simultaneous process. These and other results contributed to determination of suitable reaction conditions for the montmorillonite-supported reagents.

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Abstract  

Radiation induced decomposition of solid alkali metal nitrates at room temperature has been studied up to an absorbed dose of 300 kGy. [NO 2 ] increases with absorbed dose. From the kinetic scheme
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$NO_3^ - \xrightarrow{{{}^k1}}NO_2^ - + 0; O + NO_2^ - \xrightarrow{{{}^k2}}NO_3^ - ;$$ \end{document}
and
\documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{upgreek} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} $$O + NO_3^ - \xrightarrow{{{}^k3}}NO_2^ - + O_2$$ \end{document}
, rate constants have been evaluated for the overall radiolytic decomposition of alkali metal nitrates. This kinetic scheme is applicable in the low dose range. At higher doses, however, the radiation induced reaction, NO 2 +1/2 O2 NO 3 may also contribute. The overall rate constants are 0.13×10–6 (LiNO3), 1.05×10–6 (NaNO3), 10.10×10–6 (KNO3), 9.50×10–6 (RbNO3) and 25.50×10–6 (CsNO3) kGy–1.
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Abstract  

Two bis(bipyridine) polymeric metal nitrate complexes with 4,4’-bipyridine of simple formula like [M(bipy)2](NO3)2⋅xH2O (where M=Co, Ni and Cu; x=4, 2 and 0, respectively) have been prepared and characterized. Their thermal decomposition has been undertaken using simultaneous TG-DTG-DTA and DSC in nitrogen atmosphere and non-isothermal TG in air atmosphere. Isothermal TG has been performed at decomposition temperature range of the complexes to evaluate the kinetics of decomposition by applying model-fitting as well as isoconversional method. Possible mechanistic pathways have also been proposed for the thermolysis. Ignition delay measurements have been carried out to investigate the response of these complexes under the condition of rapid heating.

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Abstract  

Lead zirconate titanate (PZT) ceramic powder has been synthesized from metal nitrate solutions using the EDTA-gel method with different nitric acid/EDTA ratios. It was found that the thermal decomposition of the precursor was strongly affected by the nitric acid/EDTA ratio, the amount of sample, the atmosphere, and the heating rate. Crystallization of the perovskite PZT phase initiated at external temperatures as low as 250°C, as a result of the exothermic decomposition reaction of the nitrate-EDTA complexes. Possible reaction schemes are suggested and discussed to describe the thermal decomposition of PZT-EDTA precursors under different experimental conditions.

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Six alkali metal nitrates and nitrites were evaporated in vacuum at a constant heating rate in a combined mass spectrometric and thermogravimetric apparatus. Time resolved profiles of decomposition gases and kinetics were obtained for LiNO3, NaNO3, KNO3, Na/KNO3, NaNO2 and KNO2. Activation energies for the evaporation of these salts were calculated and compared to previous results of isothermal experiments. In the temperature range 650–850 K, the decomposing nitrates released NO, N2 and O2 while the nitrites released only NO and N2.

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(ethylenediamine) metal nitrates and their role in the burning rate of solid propellants . Propellants Explos Pyro . 2003 ; 28 : 5 231 – 239 . 10.1002/prep.200300010 . 2. Singh , G , Prem Felix , S

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