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Journal of Thermal Analysis and Calorimetry
Authors: Abdelhamid Harabi, Djamel Belamri, Noureddine Karboua, and Fatima-Zohra Mezahi

, respectively. Indeed, the variation in density value (0.16 g/cm 3 ) in the first stage was lower than that in the second stage (0.65 g/cm 3 ). The X-ray analyses of samples using CS are illustrated in Fig. 4 . These X-ray diagrams show that HA is

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Abstract  

The mixed zirconium, titanium, hafnium and first-row transition metal oxides (containing phosphorous oxide) were prepared using ion exchange method followed by calcinations at 1020 K during 12 h. The resulted mixed oxides were identified by XRPD method and studied their thermal behaviour by TG-DTA analysis. As a result of thermal analysis there were found one exothermic (with a peak at about 950 K), and one endothermic (with a peak at about 1300 K) processes, both without mass loss. The observation was valid for all investigated samples. The analysis of XRPD patterns of the investigated samples showed well-defined crystal phases characteristic of each oxide. The XRPD analysis also verified the phase transition of tetravalent metal oxides from orthorhombic to tetragonal, observed by DTA analysis.

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Summary The solubility of CoSeO3-SeO2-H2O system in the temperature region 298-573 K was studied. The phase diagram of cobalt(II)selenites was drawn and the crystallization fields for the different phases were determined. Depending on the conditions for hydrothermal synthesis, CoSeO3×2H2O, α-CoSeO3×1/3H2O, β-CoSeO3×1/3H2O, CoSeO3, Co(HSeO3)2×2H2O and CoSe2O5 were obtained. The different phases were proved and characterized by chemical and X-ray analyses, as well as IR spectroscopy.

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The effect of certain promoters on TiO2 crystal structure transformation was studied by mean thermal and X-ray analyses. It was found that the addition of rutile nuclei and potassium, phosphorus, zinc, magnesium, and aluminium compounds to hydrated titanium dioxide before calcination process influences on the initial temperature and anatase transformation.

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Abstract  

Mono- and binuclear rubidium-sodium halidothiocyanatobismuthates(III) have been prepared. Thermal, chemical and X-ray analyses were used to establish the thermal decomposition course of these complexes. The pyrolysis occurs in three stages connected with the mass loss and exothermic effects. The decomposition temperatures of the title salts are 190–210°C.

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Abstract  

The solubility isotherm of the three-component system Yb2O3-SeO2-H2O at 100C was studied. There are two fields of crystallization in the solubility diagram at this temperature - a small one of Yb2(SeO3)34H2O and a large one of YbH(SeO3)22H2O. These compounds were identified by the Schreinemakers' method, and by chemical and X-ray analyses as well. Simultaneous TG and DTA curves of the two compounds obtained were made and the mechanism of the thermal decomposition was described.

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Abstract  

The sorption of cobalt on natural and modified clinoptiolites has been studied. It has been demonstrated that the higher sorption of cobalt on modified clinoptinolites than on natural ones is due to precipitation reactions. The precipitates formed on the sorbent have been investigated by infrared spectrometrical, microscopical, and X-ray analyses. The capacity values of the corresponding metal forms of clinoptilolite have been obtained with cobalt. Desactivation of radioactive solutions containing134Cs,137Cs204Tl and The sorption of cobalt on natural and modified clinoptiolites has been studied. It has been demonstrated that the higher sorption of cobalt on modified clinoptinolites than on natural ones is due to precipitation reactions. The precipitates formed on the sorbent have been investigated by infrared spectrometrical, microscopical, and X-ray analyses. The capacity values of the corresponding metal forms of clinoptilolite have been obtained with cobalt. Desactivation of radioactive solutions containing134Cs,137Cs,204Tl and60Co ions simultaneously on natural sorbents by precipitation reaction has been achieved.

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Interactions of different heterocyclic compounds with monoionic forms of montmorillonite

Thermal, IR-spectral and X-ray studies of Ni(II)-montmorillonite with 3-R-and 2-R pyridines ( R =CH3, Cl, NH2)

Journal of Thermal Analysis and Calorimetry
Authors: E. Jóna, G. Rudinská, M. Sapietová, V. Pavlík, M. Drábik, and S. Mojumdar

Abstract  

Interactions of 3-R-and 2-R pyridine (R=CH3, Cl, NH2) with Ni(II)-exchanged montmorillonite have been studied. Thermal and X-ray analyses indicate that pyridine derivatives are intercalated into the interlayer spaces of montmorillonite. Infrared spectral data shown that the Lewis and/or Br�nsted type of interactions of pyridine derivatives is connected with different steric and inductive effects of the substituents (R) on the pyridine ring. The alkylpyridines increase the electron density on the donor nitrogen atom and support the coordination to the central atom. The halogen substituents have a negative inductive effect (–I), so that those ligands show a lower basicity and weaker σ-bonding properties than pyridine and also the lower possibility of the coordination.

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The system CePO4 — NaPO3 was investigated by differential thermal and X-ray analyses and infrared spectroscopy and its phase diagram was established. The system contains only one intermediate compound, NaCeP2O7, which melts incongruently at 800°. It exhibits a polymorphic transition at 595°. The low-temperature modification has an orthorhombic unit cell with the parameters.a=5.28,b=12.65,c=4.31 Å,a=β=γ=90° andV= 288.1 Å3.

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Abstract  

The processes of thermal decomposition of silver(I) and mercury(I) anthranilates and salicyloaldoximates were studied. Thermal, chemical and X-ray analyses and infrared spectroscopy were used to determine the mechanisms of decomposition of these complexes. The factor determining the decomposition is the character of the Ag+ and Hg 2 2+ ions, which are easily reduced to free metals. The final reaction product of the compounds of silver is the pure metal; the compounds of mercury are volatilized completely when heated.

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