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Abstract  

The paper describes the results of differential thermal analysis of the octahedral Fe(III) complexes of the general formula [Fe(HLn)2]Cl and Fe(HL3)L3, as well as of the corresponding ligands H2Ln (H2Ln — tridentate salicylaldehyde semi thiosemi- and S-methylisothiosemi-carabazones with n=1, 2 and 3 respectively). The decomposition of the complexes involving sulphur-containing ligands (H2L2 and H2L3) starts with sulphur elimination. In case of the complexes [Fe(HL2)]Cl and [Fe(HL3)]Cl sulphur evolves independently, whereas with Fe(HL3)L3 it is eliminated within the SCH3 group. In the former case, sulphur elimination takes place at the same temperature for both complexes. The change in the coordination mode, being a consequence of the replacement of O by S, has no essential effect on thermal stability of the coordination polyhedron. The complexes involving ONN coordination, realized with the H2L3 ligand, exhibit a comparatively highest thermal stability of the coordination polyhedron.

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Abstract  

Hexogen can be used pressed only if its crystals are covered by some polymeric material [1], either natural or artificial. Montan waxes, as natural polymeric materials, were used for the phlegmatization. The melting process of seven types of waxes was analyzed by differential scanning calorimetry. The thermal decomposition processes of hexogens and phlegmatized hexogens were investigated by dynamic differential scanning calorimetry and dynamic thermogravimetric analyses. Kinetic parameters of the decomposition processes of hexogens were evaluated by using data obtained from differential scanning calorimetric curves.

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Abstract  

The thermal decompositions of a double-base propellant (DB), five triple-base propellants (TB) and nitroguanidine (NGV) were examined. The kinetic parameters were evaluated using the ASTM, Kissinger, Rogers-Morris, Freeman-Carroll and Borchardt-Daniels methods. The values of the orders of some of the chemical reactions (n), like some values of activation energies (Ea), do not have any physical meaning, but they represent the manner of propellant decomposition and prove that the mechanism of the reaction changes during the decomposition process. As a result of this fact, differences appear in the evaluated kinetic parameters between various methods.

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The unit cell parameters and the space group of the investigated compound were determined by means of X-ray diffraction.

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Abstract

Kinetic analysis of the crystallization process in Bi4(As2S3)96 and Bi6(As2S3)94 glasses was performed based on DSC curves recorded under non-isothermal measurement conditions. Samples were thermally treated at different heating rates in the temperature range 300–770 K. The activation energy of crystallization E and the pre-exponential factor K 0 are determined by the Kissinger method and the characteristic crystallization parameters m and n of investigated glasses by the Matusita method. For both crystallization processes the glass with 4 at.% of Bi is characterized by the mechanism of volume nucleation, which is manifested in the form of two-dimensional growth at the first crystallization process, and as three-dimensional at the second one. On the other hand, in the sample with 6 at.% Bi, the average value of the parameter m is close to one, which indicates one-dimensional crystal growth. Compatibility of the values of the parameters m and n suggests that this sample has a large number of crystallization centers, which do not increase significantly during the thermal treatment.

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Metal complexes with pyrazole-derived ligands

IV. Thermal decomposition of cobalt(II) complexes with 3(5)-anmo-4-acetyl-5(3)-methylpyrazole

Journal of Thermal Analysis and Calorimetry
Authors:
A. F. Petrović
,
S. R. Lukić
,
D. M. Petrović
,
E. Z. Ivegeš
, and
V. M. Leovac

The thermal decomposition of tetrahedral cobalt(II) complexes with 3(5)-amino-4-acetyl5(3)-methylpyrazole (HL) of the general formula [Co(HL)2X2] (X=Cl, Br, I, NCO, NCS) and octahedral [Co(HL)2(H2O)4](NO3)2 and [Co(HL)2−N(CN)2}2] complexes was investigated in air atmosphere in the interval from room temperature to 1000°C. Decomposition of the complexes occurred in several successive endothermic and exothermic processes, and the residue was in all cases CoO.

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Abstract  

Activity concentrations of 40K and 3H in drinking water from four sources in the vicinity of NPP Krško and their correlation with geological data are presented. The data extends from the year 1996 until present. In addition, activity concentrations of 40K in drinking water at randomly selected sources in Slovenia are presented on a map. These activity concentrations vary by more than an order of magnitude with the largest values in northeastern part of the country.

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Abstract  

Results of thermal investigations of the amorphous five-component chalcogenide system Ge20As14(SexS1−x)52I14 are presented. Differential thermal analysis (DTA), derivative differential thermal analysis (DDTA), and dilatometry were employed to determine the temperatures of softening and partial crystallization of the samples. Thermal treatment of the samples at 1000°C and recording of the corresponding thermogravimetric (TG) and derivative thermogravimetric (DTG) curves allowed an elucidation of the full mechanism of their decomposition, which proceeds via seven characteristic phase transitions.

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