I. Giolito

Thermal decomposition of the hydrated basic carbonates of lanthanides and yttrium

Thermogravimetry, differential thermal analysis, differential scanning calorimetry, IR absorption spectroscopy, X-ray diffraction, and other methods of analysis have been used in the characterization and study of the thermal decomposition of the basic carbonate hydrates of lanthanides and yttrium. These compounds were obtained by precipitation from homogeneous solutions via the hydrolysis of urea, without the addition of an auxiliary anion. The results show that the TG and DTA curves are characteristic for each compound. The results also permit suggestions concerning the compositions and mechanisms of thermal decomposition of these compounds.

Thermal behaviour of the basic carbonates of lanthanum-europium

Abstract The basic carbonates of lanthanum with 10%, 20%, 50% and 80% of europium were prepared by precipitation from homogeneous solutions via the hydrolysis of urea, without the addition of an auxiliary anion, at two different temperatures. Elemental analysis, complexometric methods, X-ray diffraction patterns, solid state IR absorption, thermogravimetry/derivative thermogravimetry (TG/DTG) and differential thermal analysis (DTA) were used to characterise the compounds and study their thermal behaviour.

Evaluation of the relative acid strength of cerium and calcium exchanged Y zeolite by TG and DSC

Abstract The relative acid strength of cerium and calcium Y zeolite was evaluated by thermogravimetry (TG) and differential scanning calorimetry (DSC) methods, using n-butylamine as a molecular probe. The total acidity was calculated from TG curves whereas the relative acid strength given in J per acid site was determined by the DSC curves, using the Borchardt-Daniels kinetic model. The enthalpies of these processes are proportional to the acid-site strength in each specific temperature range.

Studies on double selenates. I. Thermal decomposition of lanthanum and alkali metal double selenates

Abstract Thermogravimetry, differential thermal analysis and other methods of analysis have been used to study the decomposition of hydrated lanthanum and alkali metal double selenates up to 1300°C. The results showed slight variations in the initial temperature of the various intermediate decomposition stages of the double selenates, as compared with the initial temperature of the corresponding decomposition of the simple selenates. The results also permitted the suggestion of mechanisms of thermal decomposition of these compounds.

THERMAL-DECOMPOSITION OF THE HYDRATED BASIC CARBONATES OF LANTHANIDES AND YTTRIUM IN CO2 ATMOSPHERE

Abstract The hydrated basis carbonates of lanthanides and yttrium were prepared by precipitation from homogeneous solution via the hydrolysis of urea, without the addition of an auxiliary anion. Thermogravimetry, derivative thermogravimetry (TG-DTG), and differential thermal analysis (DTA) have been used in the study of these compounds in CO 2 atmosphere. The results lead to the composition and thermal stability of the studied compounds, and also to a comparative study with reported results in air atmosphere.

Thermal decomposition of some dimethylsulphoxide (DMSO) lanthanide complexes

Abstract Compounds of composition LnCl 3 ·3MDSO (Ln = Dy-Lu) were prepared and characterized. The thermal decomposition was investigated by TG and DSC techniques.

Thermal decomposition of hydrated selenites of trivalent lanthanides and yttrium

Abstract Hydrated lanthanide(III) and yttrium(III) selenites were prepared. Simultaneous thermogravimetric and differential thermal analysis, classical differential thermal analysis , X-ray diffraction and other methods of analysis have been used in the characterisation as well as in the study of the thermal decomposition of these compounds. The results led to the composition and thermal stability and also to interpretations concerning the thermal decomposition mechanisms.

Studies on double selenates. V. Thermal decomposition of europium and alkali metal double selenates

Abstract Thermogravimetry, differential thermal analysis and other methods of analysis have been used to study the decomposition of hydrated lanthanum and alkali metal double selenates up to 1300°C. The results showed slight variations in the initial temperature of the various intermediate decomposition stages of the double selenates, as compared with the initial temperature of the corresponding decomposition of the simple selenates. The results also permitted the suggestion of mechanisms of thermal decomposition of these compounds.

THERMAL-DECOMPOSITION OF MAGNESIUM AND CALCIUM SELENATES

The effect of catalyst on the thermal decomposition of Mgso4 and Caso4 in vacuum was studied as a function of time in Knudsen cells and for MgS04, in open crucibles in vacuum in a Thermal Gravometric Appa.ratus. Platinum and Fe2o3 were used as catalysts. The caso4 decomposition rate was approximately doubled when Fe2o3 was present in a Knudsen cell. Platinum did not catalyze the caso4 deco•position reaction. The initial decomposition rate for Mgso4 was approximately 5 ·times greater than when additives were present in Knudsen cells but only about 1.5 times greater when decomposition was done in an open crucible. To determine whether or not the equilibrium pressures of so2,o2, and so3 are approached in the powder bed when Mgso4 is heated in vacuum, the effect of sample size (powder bed depth) and temperature on the initial decomposition flux from open crucibles was studied. At 1123 K the initial decomposition flux is approximately bed depth independent~ This bed depth independence indicates that a metastable equilibrium is established when so3 chemisorption pressures are 101 or lo-3 times the equilibrium values calculated from alternate sources of thermochemical data. The maximum value for the enthalpy of the metastable equilibrium, MgS04(s) = MgO(s) + so3(g), was calculated to

Thermal study of δ-valerolactam complexes of lanthanoid perchlorates

Abstract The thermal behaviour of complexes with compositions [LnL 8 ](ClO 4 ) 3 (Ln = La-Ho) and [LnL 7 ](ClO 4 ) 3 (Ln = Er-Lu, Y and L = δ-valerolactam) has been investigated by applying TG, DTG and DSC techniques under various conditions.