排序方式: 共有18条查询结果,搜索用时 15 毫秒
1.
The thermal analysis of CoC2O4·2H2O, Co(HCOO)2·2H2O and Co(CH3COO)2·4H2O was carried out with simultaneous TG-DTG-DTA measurements under non-isothermal conditions in air and argon atmospheres.
The intermediates and the end products of decomposition were characterised by X-ray diffraction and IR and UV-VIS spectroscopy.
The decomposition of the studied compounds occur in several stages. The first stage of dissociation of each compound is dehydration
both in air and argon. The next stages differ in air and argon. The final product of the decomposition of each compound in
air is Co3O4. In argon it is a mixture of Co and CoO for cobalt(II) oxalate and cobalt(II) formate but CoO for cobalt(II) acetate.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
2.
E. Ingier-Stocka 《Journal of Thermal Analysis and Calorimetry》1997,50(4):603-616
The thermal decomposition of [Co(NH3)6]2(C2O4)3·4H2O was studied under isothermal conditions in flowing air and argon. Dissociation of the above complex occurs in three stages. The kinetics of the particular stages thermal decomposition have been evaluated. The RN and/or AM models were selected as those best fitting the experimental TG curves. The activation energies,E, and lnA were calculated with a conventional procedure and by a new method suggested by Kogaet al. [10, 11]. Comparison of the results have showed that the Arrhenius parameters values estimated by the use of both methods are very close. The calculated activation energies were in air: 96 kJ mol–1 (R1.575, stage I); 101 kJ mol–1 (Ain1.725 stage II); 185 kJ mol–1 (A
2.9, stage III) and in argon: 66 kJ mol–1 (A
1.25, stage I); 87 kJ mol–1 (A
1.825, stage II); 133 kJ mol–1 (A
2.525, stage III). 相似文献
3.
Ewa Ingier-Stocka 《Thermochimica Acta》2005,432(1):56-69
The main goal of the presented work was to verify the previously assumed decomposition stages of [Co(NH3)6]2(C2O4)3·4H2O (HACOT) [Thermochim. Acta 354 (2000) 45] under different atmospheres (inert, oxidising and reducing). The gaseous products of the decomposition were qualitatively and quantitatively analysed by mass spectrometry (MS) and Fourier-transformed infrared spectroscopy (FT-IR). It was confirmed that the gaseous products of HACOT decomposition under studied atmospheres there were H2O (stage I) and NH3, CO2 (stage II). The main gaseous products in the third stage in argon and hydrogen (20 vol.% H2/Ar) were CO and CO2, whereas in air (20 vol.% O2/Ar) only CO2 was identified. Under the oxidising as well as reducing atmospheres the influence of secondary reactions on the composition of both, solid and gaseous products was found particularly strong during the third stage of the process. The studies of the multistage decomposition of HACOT, additionally complicated by many secondary reactions, required application of the hyphenated TA-MS or TA-FT-IR techniques combined with the pulse thermal analysis PTA® allowing quantification of the spectroscopic signals and investigation of gas-solid and gas-gas reactions in situ. 相似文献
4.
Rycerz L. Cieślak-Golonka M. Ingier-Stocka E. Gaune-Escard M. 《Journal of Thermal Analysis and Calorimetry》2003,72(1):231-239
Several experimental techniques were used to characterise the physicochemical properties of the TbBr3-NaBr system. The phase diagram determined by DSC, exhibits an eutectic and a Na3TbBr6 stoichiometric compound that decomposes peritectically (759 K) shortly after a solid-solid phase transition (745 K). The
eutectic composition, x(TbBr3)=39.5 mol%, was obtained from the Tamman method. This mixture melts at 699 K. With the corresponding enthalpy of about 16.1
kJ mol-1. Diffuse reflectance spectra of the pure components and their solid mixtures (after homogenisation in the liquid state) confirmed
the existence of new phase exhibiting its own spectral characteristics, which may be possibly related to the formation of
Na3TbBr6 in this system. Additionally, the electrical conductivity of TbBr3-NaBr liquid mixtures was measured down to temperatures below solidification over the whole composition range.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
Rycerz Leszek Ingier-Stocka Ewa Gaune-Escard Marcelle 《Journal of Thermal Analysis and Calorimetry》2009,97(3):1015-1021
Journal of Thermal Analysis and Calorimetry - Phase equilibrium in the CeBr3–CsBr binary system was established from differential scanning calorimetry (DSC). This system includes three... 相似文献
6.
M. Cieslak-Golonka E. Ingier-Stocka A. Bartecki 《Journal of Thermal Analysis and Calorimetry》1995,43(1):157-167
The activation energy,E a taken from the thermal decomposition of KMnO4 and AgMnO4 was compared with the energy of the longest wavelength O→Mn ‘charge transfer’ (CT) transition. TheE a and CT correlation was found in these systems. However, such relationship can be valid when in the dissociation process the electron transfer is assumed to be the rate determining step. Thus, the permanganates as well as the previously studied chromates, are positive examples showing that in some cases, the energies derived from both methods can be comparable. 相似文献
7.
E. Ingier-Stocka 《Journal of Thermal Analysis and Calorimetry》1991,37(4):769-776
The thermal decomposition of [Co(NH3)5Cl]Cl2 was studied under non-isothermal conditions, in dynamic air and argon atmospheres. The kinetics of the particular stages of [Co(NH3)5Cl]Cl2 thermal decomposition were evaluated from the dynamic weight loss data by means of the modified Coats-Redfern method. TheD n andR n models were selected as the models best fitting the experimental TG curves. These models suggest that the kinetics and macromechanism of [Co(NH3)5Cl]Cl2 decomposition can be governed by diffusive and/or phase boundary processes. The values of the activation energy,E a, and the pre-exponencial factor,A, of the particular stages of the thermal decomposition were calculated. 相似文献
8.
The thermal decomposition process of mixtures of CoC2O4⋅2H2O (COD) or Co(HCOO)2⋅2H2O (CFD) or [Co(NH3)6]2(C2O4)3⋅4H2O (HACOT) with activated carbon was studied with simultaneous TG–DTG–DTA measurements under non-isothermal conditions in argon
and argon/oxygen admixtures. The results show that the thermal decomposition of the studied mixtures in Ar proceeds in the
same manner. It begins with the salt decomposition to Comet+CoO mixture followed by (T>680 K) the simultaneous reduction of CoO to Cometand carbon degasification. The final product of the thermal decomposition of COD-C and CFD-C mixtures, identified by XRD,
is β-Co. Cobalt contents determined in the final products fall in the range 71–78 mass%. The rest is amorphous residual carbon.
In Ar/O2 admixtures the end product is Co3O4 with ash admixture.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
9.
L. Rycerz E. Ingier-Stocka S. Gadzuric M. Gaune-Escard 《Journal of Molecular Liquids》2008,140(1-3):78-83
The electrical conductivity of all EuBr2–alkali metal bromide liquid mixtures was measured as function of temperature over the whole composition range. The activation energy, EA, was evaluated for all liquid mixtures. It was revealed that the classical Arrhenius dependence did not stand for any individual mixture. The obtained results were discussed in terms of complex formation in the melts. 相似文献
10.
Leszek Rycerz Ewa Ingier-Stocka Slobodan Gadzuric Marcelle Gaune-Escard 《Journal of Thermal Analysis and Calorimetry》2010,101(2):455-461
Differential Scanning Calorimetry was used to study phase equilibrium in EuBr2–RbBr binary system. It was established that this system includes two eutectics and three stoichiometric compounds. First
of them, Rb2EuBr4, decomposes peritectically at 778 K. Second one, RbEuBr3, undergoes the solid–solid phase transition at 732 K and melts incongruently at 852 K. Third compound, RbEu2Br5, melts congruently at 888 K. The composition and temperature values of eutectics were determined as x(EuBr2) = 0.316; T
eut = 776 K and x(EuBr2) = 0.797; T
eut = 859 K. Mixing enthalpy was measured by direct calorimetry on the whole composition range. The minimum of the mixing enthalpy
occurs around the composition x(EuBr2) ≈ 0.4. The electrical conductivity of liquid mixtures was also investigated over the whole composition range and measured
down to temperatures below solidification. The specific conductance (liquid phase) plotted against the mole fraction of EuBr2 shows a broad minimum at x(EuBr2) ~ 0.6. The activation energy for conductivity changes with temperature. Results obtained are discussed in terms of possible
complex formation. 相似文献