Thermal Behaviour of the N-donor Adducts of Metal Saccharinates III. Imidazole saccharinates of Co(II), Ni(II) and Cd(II)

The complexes [M(HIm)₄(H₂O)₂](sac)₂ (M=Co, Ni) and [Cd(HIm)₂(sac)₂]₂ with saccharin (sac) and imidazole (HIm) were synthesized and their thermal (TG, DTG and DTA) behaviour in the interval from room temperature up to 1000°C in a static air atmosphere was investigated. Irrespectively of whether the deprotonated saccharinato residues are present as ligands or ions or both as ligands and ions, the anhydrous complexes regularly decompose in two stages. The thermal data of 16 saccharinato complexes (including the title compounds) were correlated with the respective structural data. The general thermal stability order of the saccharinato complexes can be represented as: Pb(II)<Zn(II)<Co(II)Ni(II)<Cd(II) (the stability of the Cu saccharinates depends on the particular compound) and is dictated by several structural factors, e.g. metal ionic radii, participation of the water in the coordination sphere of the metal and other structural characteristics. This revised version was published online in August 2006 with corrections to the Cover Date.     

Synthesis and neel temperature determination of ferrites from the MO−ZnO−Fe2O3 systems (M=Cu,Co and Ni)

The Curie (Neel) temperature is successfully determined by means of a simple magnetic device attached to the Q Derivatograph (MOM, Hungary), which is widely used in many laboratories. This possibility is demonstrated by a study of ferrite materials with general formula M_xZn_1?xFe₂O₄ (M=Cu, Co and Ni;x=0.0; 0.2; 0.4; 0.5; 0.6; 0.8; 1.0). X-ray phase analysis, Mössbauer spectroscopy and microscopic examinations revealed that the obtained ferrites are monophase samples. The mixed ferrites possess more strongly expressed magnetic properties than those of the individual ferrites; the maximum magnetic interaction in these ferrites is observed at different zinc contents.     

Synthesis and neel temperature determination of ferrites from the CuO−ZnO−Fe2O3 system

Conditions were established and individual and mixed ferrites with the general formula Cu_xZn_1?xFe₂O₄ (x=0; 0.1; 0.2; 0.3; 0.4; 0.5; 0.6; 0.7; 0.8; 1.0) were synthesized from the CuO?ZnO?Fe₂O₃ system. X-ray phase analysis, Mössbauer spectroscopy and microscopic examinations revealed that the obtained ferrites are monophase samples. A magnetic device was attached to the Q-Derivatograph (MOM, Hungary) and successfully used for sample investigation in a magnetic field, and in particular for Curie (Neel) temperature determination. The ferrite composition and the thermal treatment conditions were shown to correlate with the Neel temperature of the synthesized ferrites.     

Thermal study and mechanism of Ag2S oxidation in air

The results of thermal study and mechanism of the oxidation process of synthetic Ag₂S in air are presented in this article based on the comparative analysis of DTA and XRD results, as well as by constructed phase stability diagrams (PSD) for the Ag–S–O system.     

Mössbauer study of thermal magnetic transitions in Cu0.5Zn0.5Fe2O4

The dependence of the Mössbauer spectra of the ferrite Cu_0.5Zn_0.5Fe₂O₄ on the temperature is investigated. The profiles of the hyperfine magnetic fields distributionP(H) are obtained from the spectra by a decomposition method. The results are interpreted by assuming a variation of the magnetic correlation radius in the region of the thermal magnetic transition.     

57Fe Mössbauer study of the electrochemical reaction of Li with FeP y (y = 1,2)

A complete ⁵⁷Fe Mössbauer study was undertaken to elucidate the electrochemical mechanism occuring during the cycling of the FeP _x (x?= 1,2)/Li batteries. Upon discharge, for FeP, the conversion reaction FeP + 3Li → Fe + Li₃P was confirmed, whereas for FeP₂, FeP and a disordered magnetic unknown phase A are observed. On charge, the starting material is partially reconstructed only in the case of FeP. Once the first cycle is achieved, the same redox process occurs in both the FeP/Li and FeP₂/Li cells, between LiFeP, FeP, Fe° (or phase A) and Li₃P.     

The electrochemical reactivity of the NiP<Subscript>3</Subscript> skutterudite-type phase with lithium

We report the electrochemical Li reactivity of the cubic NiP₃ phase, a candidate for anode applications for Li-ion batteries. NiP₃ reacts with nine lithium per formula unit leading to a first cycle reversible capacity of 1,475 mAh/g at an average potential of 0.9 V vs. Li+/Li°. Electrochemical measurements and complementary X-ray diffraction showed that NiP₃ presents a conversion process competing with an insertion process. A good cycleability may only be obtained on a limited potential window, excluding the low-potential region. This paper was presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15, 2007.     

Oxidation of Metal Sulphides and Determination of Characteristic Temperatures by DTA and TG

The oxidation of metal sulphides and sulphide concentrates was studied by means of DTA, TG and DTG curves. The behaviour of ZnS, CdS, GaS, Tl₂S, Sb₂S₃ and Sb₂S₅ during thermal treatment in an oxidizing medium was investigated. The properties of these sulphides were compared and conclusions were drawn about their probable oxidation reactions and the kind of end-products obtained. The characteristic temperatures of the studied sulphides were determined on the basis of curves (DTA). The values obtained were used to compare the behaviour of the sulphides during the oxidation process in a fluid bed. The results can be used to improve the technological and economic indices in the industrial production of zinc. This revised version was published online in July 2006 with corrections to the Cover Date.     

Synthesis,characterisation and thermal decomposition of double sulfate

Upon evaporation at room temperature of an aqueous mixture containing Al(III) sulfate and trishydroxymethyl-ammoniummethane sulfate in a molar ratio 1:2, double sulfate as crystalline product was obtained. The stoichiometry of the obtained compound was determined by means of elemental and TG analysis. For identification, IR-spectra and X-ray powder diffraction patterns were done. It was found that the general formula of the obtained compound is Al(HOCH₂)₃CNH₃(SO₄)₂·₆H₂O. as revealed by TG, DTG and DTA analysis, the dehydration of the AL-compound takes place in one step which points out that the six water molecules are bonded in the same way. The thermal decomposition of the anhydrous compound starts at about 260°C and is very complex. This process takes place in many steps which are not well resolved. The pathway of the thermal decomposition is also supposed. This revised version was published online in July 2006 with corrections to the Cover Date.