Synthesis, evolved gas analysis (EGA) during pyrolysis and spectroscopic study of light lanthanide nicotinate in solid state

Abstract

Solid-state Ln(C-9 H5NO2)(3)center dot 2H(2)O, where Ln stands for light trivalent lanthanides (La to Gd, except Pm) and C9H5NO2 is nicotinate, were synthesized. The methods of simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC), elemental analysis, and complexometry were used to establish the stoichiometry and evolved gas analysis (EGA) for TG-DSC coupled to Fourier transform infrared spectroscopy (FTIR) in order to study the thermal behavior of these compounds in CO2 and N-2 atmospheres. The use of density functional theory (DFT) and FTIR were performed in order to propose the structure and the type of existing coordination of the synthesized compounds. All the compounds were obtained in a dehydrated form, and in both the atmospheres dehydration occurred in two consecutive stages, with losses of 1.5 and 0.5 H2O respectively. The final residues of thermal decomposition in CO2 atmosphere were: CeO2 and Ln(2)O(3) (Ln = La, Pr, Nd, Sm, Eu, Gd). In N-2 atmosphere, the mass losses were still being observed up to 1000 C for all the compounds. (C) 2014 Elsevier B.V. All rights reserved.