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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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computing because it has high resistance to laser induced damage, low angular sensitivity and good mechanical hardness compared to many organic NLO crystals [ 1 – 4 ]. Metal ion doped materials are currently receiving a great deal of attention due to the

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Journal of Thermal Analysis and Calorimetry
Authors: M. Ştefănescu, O. Ştefănescu, M. Stoia, and C. Lazau

Abstract  

In this paper we present a study on the synthesis of Fe(III) oxide, by thermal decomposition of some complex combinations of Fe(III) with carboxylate type ligands, obtained in the redox reaction between some polyols (ethylene glycol (EG), 1,2-propane diol (1,2PG), 1,3-propane diol (1,3PG) and glycerol (GL)) and NO3 ions (from ferric nitrate). Fe2O3 was obtained by thermal decomposition of the synthesized metal-organic precursors at low temperatures. γ-Fe2O3 was obtained as nanoparticles at 300C, while at higher temperatures α-Fe2O3 starts to crystallize and becomes single phase at ~500C. The formation of the metal-organic precursors and their thermal decomposition were studied by thermal analysis and FTIR spectroscopy. The evolution of Fe2O3 crystalline phases with the thermal treatment of iron complexes was followed by RX diffractometry. The size of γ-Fe2O3 nanoparticles was estimated by transmission electron microscopy (TEM).

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157 131 135 Naár Z. and Bíró B. 2006. Species composition of indigenous Trichoderma fungi affected by Cd, Ni and Zn heavy metals in calcareous

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Abstract  

A novel microthermogravimetric apparatus to study the kinetics of metal sulphur reactions and transport properties of transition metal sulphides has been described. The main feature of this arrangement includes the application of the carrier gas for sulphur vapour transportation and the protection of the balance chamber from sulphur attack. As a consequence, the helix balance could have been replaced by an automatic electronic microbalance and the accuracy of the mass change measurements increased more than two orders of magnitude, up to 10–7 g. The application of two liquid sulphur reservoirs created very stable, strictly defined reaction conditions, and enabled to make rapid changes of sulphur partial pressure in the reaction chamber. It has been demonstrated that all these innovations make it possible to study not only the kinetics of very slow sulphidation processes but also to determine deviations from stoichiometry and defect mobility in transition metal sulphides.

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Abstract  

Interaction of albumin with no-carrier-added metal radionuclides was studied in multielemental environment using dialysis technique. No-carrier-added 197mHg, 199–201Tl, 199–200Pb, 204Bi and 204,205Po were produced by irradiating Au target consecutively with 7Li and 12C beams. Similarly, 61Cu, 66–68Ga, 62,63Zn, 66,67,69Ge, 71,72As and 73Se were produced by irradiating cobalt target consecutively with 16O, 7Li and 12C projectiles. These no-carrier-added radionuclides were chemically separated from the bulk target before studying their interaction with albumin. It was found that Hg and Ga strongly bind with albumin, whereas Bi, Po, As, and Se do not bind at all with albumin. The binding affinities of Pb, Tl, Cu and Zn radionuclides towards albumin are moderate.

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Abstract  

Studies on the thermal decomposition of the acetyl acetonate complexes of transitional metal ions Cu/II/, Cr/III/, Mn/II/, Co/II/, Fe/III/, Vo/II/, Zn/II/, and Cd/II/ have been performed by thermogravimetric method. Taking the initial decomposition temperature as a measure of thermal stability, the relative order of the thermal stability of these complexes shows the following order: Zn/II/<Cd/II/< VO/II/<Fe/III/<Cr/III/<Cu/II/Co/II/< Mn/II/. The nature of decomposition of Cu/II/ and Cr/III/ complexes is similar, a sigmoid curve exists. In other cases a long linear decomposition follows the sigmoid pattern. The linear decomposition is a function of final decomposition temperature and percentage of decomposition. The kinetics of the decomposition is analyzed according to the Coats-Redfern equation. The results are discussed on the basis of structural and other aspects leading to the decomposition.

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montmorillonite for alkaline and alkaline earth metals have been reported in numerous studies [ 20 – 22 ]. Furthermore, more work has been focused on the effects of interlayer cations on the physicochemical properties, such as cation exchange capacity, pore

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Abstract  

Fast neutron activation analysis (FNAA) was investigated as a possible on-site preliminary screening technique for metal contamination of soil. Two metals, Cu and Zn, were used in a laboratory setting to evaluate the possibility of detecting metal contamination of soil at or below the maximum permissible metal concentration in soil. Varying quantities of compounds of the selected metals were mixed into a prepared soil column for analysis of signal intensity as a function of concentration in the soil. Experiments were conducted with a sealed tube neutron generator and a germanium gamma-ray detector. Both metals produced signal levels distinguishable from background soil concentrations at the maximum permissible level.

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The analysis of hardening of metal materials

Structural level of deformation and parameters of thermomechanical treatment

Journal of Thermal Analysis and Calorimetry
Authors: Slobodan Stojadinovic, Jasmina Pekez, and Nikola Bajic

[ 2 , 3 , 5 , 6 , 9 ], makes contributions to better understanding of the hardening of metal materials depending on TMT parameters, and with this also to more constructive designing of the technology for concrete alloys production, as steels and

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