Authors:Y. Masuda, K. Minagawa, W. Morita, Z. Zhong, and P. K. Gallagher
The behaviour of thermal dehydrations of isomorphous complexes of calcium copper acetate hexahydrate, CaCu(CH3CO2)4·6H2O and calcium cadmium acetate hexahydrate, CaCd(CH3CO2)4· 6H2O was studied by means of thermal analyses and X-ray structural analysis. The enthalpy changes for the dehydration of CaCu(CH3CO2)4·6H2O and CaCd(CH3CO2)4·6H2O were 315±9.7 and 295±8.0 kJ mol−1, respectively. The DSC curves of the dehydrations indicated that the seemingly simple dehydrations are more complex than they appear at first sight. Apparent activation energies for the dehydrations of CaCu(CH3CO2)4·6H2O and CaCd(CH3CO2)4·6H2O were 85.7±7.4 and 87.9±12.5 kJ mol−1, respectively.
Authors:V. Vassilev, L. Aljihmani, and V. Parvanova
The phase diagram of the system Ag4SSe–As2Se3
is studied by means of X-ray diffraction, differential thermal analyses and
measurements of the microhardness and the density of the materials. The unit-cell
parameters of the intermediate phases 3Ag4SSeAs2Se3
(phase A) and Ag4SSe2As2Se3
(phase B) are determined as follows for phase A: a=4.495
, b=3.990 , c=4.042
, α=89.05, β=108.98, γ=92.93; for phase
B: a=4.463 , b=4.136
, c=3.752 , α=118.60,
β=104.46, γ=83.14. The phase 3Ag4SSeAs2Se3
have a polymorphic transition α↔β consequently at 105 and 120C.
The phase A melts incongruently at 390C and phase B congruently at the
Authors:Rodica Olar, Mihaela Badea, Dana Marinescu, Larisa Calu, and Cristina Bucur
Novel complexes of type [M2LCl4]·nH2O ((1) M:Ni, n = 5; (2) M:Cu, n = 0 and (3) M:Zn, n = 2; L: ligand resulted from 1,2-phenylenediamine, 3,6-diazaoctane-1,8-diamine and formaldehyde template condensation) were synthesised and characterised. The features of complexes have been assigned from microanalytical, IR and UV–Vis data. The thermal analyses have evidenced the thermal intervals of stability and also the thermodynamic effects that accompany them. Processes as water or hydrochloric acid elimination as well as oxidative degradation of the organic ligand were observed. Complexes display a different thermal behaviour as result of dissimilar chemical interaction of metal ions with chloride anions. The final product of decomposition was metal(II) oxide as powder X-ray diffraction indicated.
The thermoanalytical curves of (C6H5)4AsCl (I) and (C6H5)4PCl (II) were generated simultaneously by using a Netzsch simultaneous thermal analyser 409 under static air and dynamic argon
atmospheres. The ranges of thermal stability of I and II were found to be 145–310°C and 137–365°C, respectively, and their
melting points to be 261 and 278°C. The DTA profiles of I and II differ and can be used for their distinction.
Authors:T. Hashimoto, M. Yoshinaga, Y. Ueda, K. Komazaki, K. Asaoka, and S. Wang
The phase transitions of Ba2-xSrxIn2O5 were investigated with various thermal analyses and high-temperature X-ray diffraction. It was clarified that crystal structure
of Ba2-xSrxIn2O5 with x=0.0~0.4 varies from brownmillerite through distorted perovskite to another distorted perovskite with increase of temperature.
The phase transition from brownmillerite to distorted perovskite was revealed to be first order, whereas transition from distorted
perovskite to another one was second order. The specimen with x≥0.5 showed only one first order phase transition from brownmillerite to distorted perovskite. The phase diagram of Ba2-xSrxIn2O5 was established and existence of tricritical point at ~1100C with x=0.4~0.5 was suggested.
Authors:P. Melnikov, R. V. Gonçalves, and H. Wender
Sb(VO3)3 has been synthesized by interaction between NH4VO3 and Sb2O3. The compound crystallizes in monoclinic system with lattice parameters: a = 17.150; b = 15.940; c = 14.600 Å and angle β = 90.50°. The scanning electronic microscopy shows thin flat plates measuring ~20 μm along with detritus material. The synthesis was simulated by thermal analysis and the final product identified by X-ray diffraction. Thermal analyses of the ternary system xNH4VO3 + (1 − x)(NH4)2HPO4 + Sb2O3 lead to the formation of Sb(VO3)3 and SbPO4 at 500 °C. At high temperature (900 °C), SbVO4, SbOPO4, VO and SbP5O14 are formed. The data of thermal analysis match with the composition of intermediate and final products. No solid solutions containing simultaneously PO4−3 and VO4−3 ions have been found.
Authors:Y. Sawada, K. Omika, Y. Ito, F. Muta, and M. Momota
The formation process of a ceramic (indium oxide) thin film (thickness: approximately 20 nm to several microns) was investigated
by thermal analyses. Thermal changes of an organic precursor, indium(III) 2-ethylhexanoate, dip-coated on a glass substrate
was successfully detected by DSC in air. Exothermic phenomena were observed at marked lower temperatures for the thin films
than for the bulk material; thinner films had slightly lower peak temperatures. The reaction mechanism is discussed with reference
to mass spectra of the evolved gases.
The ligand has been
prepared from ω-chloroisonitrosoacetophenone and 1,4-phenylenediamine
in the presence of NaHCO3. The ligand have a C=O group
and an –NH–R group adjacent to the oxime group. The Ni(II), Cu(II)
and Co(II) complexes of the synthesized ligand were prepared and their structures
were identified using FTIR, UV-Vis spectral data, elemental analysis, thermal
analysis and magnetic moment measurements. The metal-ligand ratios were found
to be 3:2. The ligands were found to coordinate to the metal ions via the
oxime nitrogen, oxime oxygen, one of the carbonyl group and amide nitrogen
atoms. Thermal analyses data reveals that the water in the complexes was found
to be non-coordinated to the metal ions. In the trinuclear structures, the
metals have the tetrahedral environments.
Grewia gum is a naturally occurring polysaccharide which has potential as a pharmaceutical excipient. Differential scanning calorimetry and Fourier transform infrared (FT-IR) spectroscopy techniques were used to examine the thermal and molecular behaviours, respectively, of mixtures of grewia gum with cimetidine, ibuprofen or standard excipients, to assess potential interactions. No disappearance or broadening of the melting endotherm was seen with cimetidine or ibuprofen. Similarly, there was no interaction between grewia gum and the standard excipients tested. The results obtained using thermal analyses were supported by FT-IR analysis of the material mixtures. Grewia gum is an inert natural polymer which can be used alone or in combination with other excipients in the formulation of pharmaceutical dosage forms.
Authors:Özlem Özen Karakuş, Gülbanu Koyundereli Çilgi, and Hasalettin Deligöz
In the present study, thermal decomposition of mono- and di-azocalixarene derivatives (A1–A8 and B1–B8) was investigated by means of thermogravimetry (TG), differential thermal analysis (DTA) and derivative thermogravimetry (DTG). The exclusion of methanol, hydrolysis of benzoyl ester and methyl ketone groups in lower rim, and decomposition of azo groups in upper rim have occurred during thermal analysis, consecutively. The thermal decomposition degrees amount of volatile pyrolysis products were determined in air atmosphere using TG, DTA and DTG curves. In conclusion, the thermal analyses of azocalixarenes demonstrated that its stability depends on the substituted groups and their positions in the calixarene structure.