Synthesis, characterization and thermal behavior on solid tartrates of light trivalent lanthanides
Solid state Ln–L compounds, where Ln stands for light trivalent lanthanides (L–Gd) and L is tartrate, have been synthesized. Thermogravimetry and differential thermal analysis (TG/DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to information about the composition, dehydration and thermal decomposition of the isolated compounds.
SYNTHESIS, CHARACTERIZATION AND THERMAL BEHAVIOUR OF SOLID-STATE COMPOUNDS OF HEAVY TRIVALENT LANTHANIDE AND YTTRIUM MANDELATES
Characterization, thermal stability and thermal decomposition of heavy trivalent lanthanide mandelates Ln(C 6 H 5 CH(OH)CO 2 ) 3 ·2H 2 O (Ln = Tb to Lu and Y) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), experimental and theoretical infrared spectroscopy, X-ray diffractometry, complexometry and TG-DSC coupled to FTIR. The dehydration of the compounds occurs in a single step and the thermal decomposition of the anhydrous ones occurs in two, three, four or five consecutive steps, with formation of the respective oxides Tb 4 O 7 and Ln 2 O 3 (Ln = Dy to Lu and Y) as final residues. The results also provided information concerning the composition, thermal behavior and gaseous products evolved during the thermal decomposition of these compounds. The theoretical and experimental spectroscopic data suggest the possible modes of coordination of the ligand with the heavy lanthanides. Theoretical 3D structure of Y(L)3•2H2O: (a), (c) and (d) isomers (less stable); (b) yttrium(III) mandelate coordinated by hydroxyl and carboxylate groups (the most stable compound).
Characterization and thermal behaviour of gel grown mixed rare-earth (Didymium) tartrate crystals
Sherulites, crystal aggregates and platelets of Di2 (C4H4O6)3 · 5H2O mixed crystals were grown in gel using the single tube diffusion method. The material was characterized by using different techniques such as chemical analysis, EDAX, X-ray and electron diffraction, infrared and mass spectroscopy. The thermal behaviour of the material was studied using differential thermal analysis, DTG, thermogravimetric analysis and differential scanning calorimetry. The material is thermally unstable and starts decomposing at 50‡ C. Thermal analysis results indicate the application of the contracting cylindrical kinetic model for the solid state reactions involved in the decomposition process. The values of kinetic parameters, e.g. order of reaction, activation energy and frequency factor are worked out. The implications are discussed.