Authors:B. Randhawa, K. Prabhjinder, and Sweety Kamaljeet
Thermal decomposition of cobalt hexa(formato)ferrate(III) decahydrate, Co3[Fe(HCOO)6]2. 10H2O, has been studied up to 973 K in static air atmosphere, employing TG, DTG, DSC, XRD, ESR, Mössbauer and infrared spectroscopic techniques. Dehydration occurs in two stages in the temperature range of 340–430 K. Immediately after the removal of the last water molecule the anhydrous complex undergoes decomposition till -Fe2O3 and cobalt carbonate are formed at 588 K. In the final stage of remixing of cations, a solid state reaction between -Fe2O3 and cobalt carbonate leads to the formation of CoFe2O4 at a temperature (953 K) much lower than for the ceramic method. A saturation magnetization value of 2310 Gauss of ferrite (CoFe2O4) shows its potential to function at high frequencies.
The complexes Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 3-(anilinomethylene)-2-methoxychroman-4-one were synthesized and characterized by elemental analysis, conductivity, infrared and UV–Vis spectroscopy, 1H NMR, X-ray diffraction patterns, magnetic susceptibility and thermal analysis (TG/DTG/DSC). The X-ray analysis shows that the studied compounds crystallize in the triclinic crystal system and they are no isostructural complexes. The unit cell parameters for these chelates were presented. The molecules of solvent are in the outside coordination sphere of the complexes. The chelates have different thermal stability and they decompose in air atmosphere in three steps. The coordination of metal ions is through nitrogen atom from ligand and oxygen atom present in 4-position of γ-pyrone. The studied chelates have electrolyte (1:1) and non-electrolyte nature. They are high-spin complexes with octahedral coordination and the weak ligand fields.
Authors:P. Budrugeac, Carmen Racles, V. Cozan, and Maria Cazacu
Thermal and thermo-oxidative stability of some poly(siloxane-azomethine)s obtaining starting from bis(formyl-p-phenoxymethyl)tetramethyldisiloxane and different organic diamines have been investigated by TG+DTG+DSC simultaneous analyses
performed in argon flow and air static atmosphere, respectively. TG, DTG and DSC curves of each polymer showed three or four
successive degradation steps at different temperatures according to the composition of the sample and the gaseous atmosphere
in which the thermal analysis was performed. For each process, the following parameters were evaluated: total mass loss, temperature
corresponding to the maximum reaction rate, maximum reaction rate, temperature corresponding to certain mass loss. In order
to determine the thermal and thermo-oxidative stabilities of investigated polymers, the following values were determined:
Tx% — temperature corresponding to x% mass loss, and %ΔmT — mass loss at a given temperature T. The obtained orders of stability were correlated with the structure of investigated polymers.
Authors:K. Mészáros-Szécsényi, E. Ivegeš, V. Leovac, A. Kovács, G. Pokol, and Ž. Jaćimović
Complexes represented by the general formula [MCl2L2] (M(II)=Zn, Mn, Co) and complexes of [Cu3Cl6L4] and CuSO4L24H2O, CoSO4L23H2O, [ZnSO4L3] where L stands for 3-amino-5-methylpyrazole were prepared. The complexes were characterized by elemental analysis, FT-IR
spectroscopy, thermal (TG, DTG, DSC and EGA) methods and molar conductivity measurements. Except for the Zn-complexes, the
magnetic susceptibilities were also determined.
Thermal decomposition of the sulphato complexes of copper(II) and cobalt(II) and the chloro complexes of cobalt(II) and manganese(II)
resulted in well-defined intermediates. On the basis of the IR spectra and elemental analysis data of the intermediates a
decomposition scheme is proposed.
The thermal analysis methods (TG, DTG, DSC, methods for shrinkage temperature evaluation) and scanning electron microscopy
(SEM) were used for investigation of the thermal behaviour and surface morphology of some recent manufactured parchments and
vegetable tanned leathers, patrimonial parchments and leathers proceeded from Romanian libraries. At the progressive heating
in static air atmosphere and in the temperature range of 20–600�C, all investigated materials exhibit three main successive
processes, associated with the dehydration and thermo-oxidative degradations.
The rate of the first thermooxidative process, temperatures corresponding to the maximum rate of the second thermooxidative
process and shrinkage temperature were associated with the damage of the investigated materials due to environmental impact.
Parchments and leathers surfaces were characterized by SEM, and specific morphological criteria were suggested for damage
assessments. These criteria were correlated with the results obtained by thermal analysis methods.
Authors:J. Santos, M. Conceiçăo, M. Trindade, A. Araújo, V. Fernandes, and A. Souza
The lanthanidic complexes of general formula Ln(C11H19O2)3 were synthesized and characterized by elementary analysis, infrared absorption espectroscopy, thermogravimetry (TG) and differential
scanning calorimetry (DSC). The reaction of thermal decomposition of complexes has been studied by non-isothermal and isothermal
TG. The thermal decomposition reaction of complexes began in the solid phase for Tb(thd)3, Tm(thd)3 and Yb(thd)3 and in the liquid phase for Er(thd)3 and Lu(thd)3, as it was observed by TG/DTG/DSC superimposed curves. The kinetic model that best adjusted the experimental isothermal thermogravimetric
data was the R1 model. Through the Ozawa method it was possible to find coherent results in the kinetic parameters and according
to the activation energy the following stability order was obtained: Tb(thd)3>Lu(thd)3>Yb(thd)3>Tm(thd)3>Er(thd)3
The thermal decomposition of manganese tris(malonato)ferrate(III) hexahydrate, Mn3[Fe(CH2C2O4)3]2 . 6H2O has been investigated from ambient temperature to 600 °C in static air atmosphere using various physico-chemical techniques,
i.e., simultaneous TG-DTG-DSC, XRD, Mössbauer and IR spectroscopic techniques. Nano-particles of manganese ferrite, MnFe2O4, have been obtained as a result of solid-state reaction between a-Fe2O3 and MnO (intermediate species formed during thermolysis) at a temperature much lower than that for ceramic method. SEM analysis
of final thermolysis product reveals the formation of monodisperse manganese ferrite nanoparticles with an average particle
size of 35 nm. Magnetic studies show that these particles have a saturation magnetization of 1861G and Curie temperature of
300 °C. Lower magnitude of these parameters as compared to the bulk values is attributed to their smaller particle size.
The thermal analysis of strontium and barium hexa(formato)ferrates(III), M3[Fe(HCOO)6]2. xH2O, has been carried out from ambient temperature to 800 °C. Various physico-chemical techniques, i.e., TG, DTG, DSC, XRD,
IR, Mössbauer spectroscopy, etc., have been employed to characterize the intermediates/end products. After dehydration, the
anhydrous complexes undergo decomposition to yielda-Fe2O3and metal oxalate in the temperature range of 275-290 °C. A subsequent oxidative decomposition of metal oxalate leads to the
formation of respective alkaline earth metal carbonate in successive stages. Finally, nanosized ferrites of Sr2Fe2O5and BaFe2O4stoichiometry have been obtained as a result of a solid-state reaction betweena-Fe2O3and a fraction of MCO3. The temperature of ferrite formation is much lower than possible in the conventional ceramic method.
Authors:A. Gouveia Souza, M. Nóbrega Machado, L. Helker-Carvalho, and M. Severo Trindade
The thermal decomposition kinetics of the solid complexes Cd(S2 CNR2 )2 , where R =C2 H5 , n -C3 H7 , n -C4 H9 or iso -C4 H9 , was studied by using isothermal and non-isothermal thermogravimetry. The superimposed TG/DTG/DSC curves revealed that thermal
decomposition reactions occur in the liquid phase. The kinetic model that best fitted the experimental isothermal TG data
was the one-dimensional phase-boundary reaction-controlled process R1 . The thermal analysis data suggested the thermal stability sequence Cd(S2 CNBun2 )2 >Cd(S2 CNPrn2 )2 >Cd(S2 CNBui2 )2 >Cd(S2 CNEt2 )2 , which accords with the sequence of stability of the apparent activation energies.
Authors:Gabriel de Araujo, Dalva de Faria, Márcio Zaim, Flávio de Souza Carvalho, Fabio de Andrade, and Jivaldo Matos
Tibolone polymorphic forms I (monoclinic) and II (triclinic) have been prepared by recrystallization from acetone and toluene,
respectively, and characterized by different techniques sensitive to changes in solid state, such as polarized light microscopy,
X-ray powder diffractometry, thermal analysis (TG/DTG/DSC), and vibrational spectroscopy (FTIR and Raman microscopy). The
nonisothermal decomposition kinetics of the obtained polymorphs were studied using thermogravimetry. The activation energies
were calculated through the Ozawa’s method for the first step of decomposition, the triclinic form showed a lower Ea (91 kJ mol−1) than the monoclinic one (95 kJ mol−1). Furthermore, Raman microscopy and DSC at low heating rates were used to identify and follow the thermal decomposition of
the triclinic form, showing the existence of three thermal events before the first mass loss.