Authors:C. -H. Horte, Chr Becker, G. Kranz, E. Schiller, and J. Wiegmann
Through a combination of X-ray diffraction and thermal analysis (simultaneous TG-DTG-DTA and quasi-isothermal TG), it was shown that the molar ratio intercalation agent/kaolinite in all intercalation compounds is approximately 1. In a saturated atmosphere of the corresponding intercalation agent, the intercalation compounds are stable up to more than 150 °C.
Thermogravimetric (TG), differential thermal analysis (DTA) and thermal degradation kinetics, FTIR and X-ray diffraction (XRD)
analysis of synthesized glycine–montmorillonite (Gly–MMT) and montmorillonite bound dipeptide (Gly–Gly–MMT) along with pure
Na–MMT samples have been performed. TG analysis at the temperature range 25–250 °C showed a mass loss for pure Na–MMT, Gly–MMT
and Gly–Gly–MMT of about 8.0%, 4.0% and 2.0%, respectively. DTA curves show the endothermic reaction at 136, 211 and 678 °C
in pure Na–MMT whereas Gly–MMT shows the exothermic reaction at 322 and 404 °C and that of Gly–Gly–MMT at 371 °C. The activation
energies of the first order thermal degradation reaction were found to be 1.64 and 9.78 kJ mol−1 for Gly–MMT and Gly–Gly–MMT, respectively. FTIR analyses indicate that the intercalated compounds decomposed at the temperature
more than 250 °C in Gly–MMT and at 250 °C in Gly–Gly–MMT.
Authors:L. Matzui, L. Vovchenko, I. Ovsienko, and E. Kharkov
Results of the investigations of deintercalation process in intercalation compounds graphite-SbCl5 and graphite-ICl are presented. It was found that sample mass losses have a step character that testifies to the discrete
transition from one stage of graphite intercalation compounds to another. The increase in the rate of heating breaks the step
character of mass loss dependence on temperature and intensive mass losses occur without stage transitions.
Authors:C. Ferragina, R. Di Rocco, A. Fanizzi, P. Giannoccaro, and L. Petrilli
Long chain alkylammonium cations can be exchanged into a preswelled phase of g-zirconium phosphate, a layered inorganic ion-exchanger.
The derived materials are used as templates to give organic-inorganic composite materials. The cationic exchange occurs very
quickly. These intercalation compounds behave in a very similar way. They are still layered and exhibit an interlayer distance
d notably greater than that of its precursor whose behavior depends on the chain length. By thermal and microanalyser characterizations
it can be observed that the surfactant is lost in two stages, the second one as a result of the fragmentation of the chain.
The layered structure with the expanded interlayer distance is maintained up to ~350C.
We present in this paper the thermal analysis (calorimetry, TG and DSC) of the first stage P2O3F4 graphite intercalate compound in atmospheric pressure and high pressure. By heating we obtain always exfoliation phenomenon.
The heating of exfoliated, graphite shows an important oxidation resistance in comparison with another exfoliated graphite.
This oxidation resistance has been studied also by thermal analysis like TG, in oxygen atmosphere.
Carbon foil rebuilding from exfolied graphite keeps these interesting antioxidation properties.
The changes resulting from the compression of graphite-CrO3 intercalation compounds are demonstrated in the TG curves. In comparison with the samples examined in the form of a flake bed, the compacted compounds begin to decompose at lower temperatures and their weight loss is higher, particularly above 220 °C. To explain the obtained results, the pressure-induced changes in the structures and the activities of the compounds are considered in relation to the method of intercalation, the concentration of the intercalant and the extent of exfoliation.
Authors:T. Tsuji, Y. Yamamura, H. Watanabe, K. Saito, and M. Sorai
The heat capacities and magnetic susceptibilities of powdered samples of FexNbS2 (x=0.14, 0.21 and 0.30) were measured at temperatures from 8 to 303 K and from 5 to 300 K, respectively. For Fe0.14NbS2, the magnetic susceptibility exhibited an anomaly as a shoulder at about 57 K, but no heat capacity anomaly was observed at this temperature, indicating the appearance of a spin-glass state. Anomalies in the heat capacity for FexNbS2 (x=0.21 and 0.30) occurred at 100.5 and 45.0 K, respectively, where the magnetic susceptibility displayed a maximum, corresponding to an antiferro-paramagnetic phase transition. The electronic state of the iron atom is discussed on the basis of entropy analysis.