Thermal investigation and infrared evolved gas analysis of solid trivalent lanthanide and yttrium α-hydroxyisobutyrates in N2 and CO2 atmospheres

Abstract

Solid-state Ln(C4H7O3)3·nH2O compounds, where Ln stands for trivalent lanthanides or yttrium and C4H7O3– is α-hydroxyisobutyrate, have been synthesized. Simultaneous thermogravimetry and differential thermal analysis (TG–DTA), elemental analysis, complexometry and TG–DSC coupled to infrared spectroscopy (FTIR) were used to characterize and to study the thermal behavior of these compounds in CO2 and N2 atmospheres. The dehydration of the compounds occurs in a single (La to Nd, Tb to Tm and Y), two (Sm and Gd) and three (Eu) steps in N2 atmosphere and a single (La, Ce, Tb to Tm and Y), two (Pr, Nd and Gd) and three (Sm and Eu) steps in CO2 atmosphere. The final residues of the thermal decomposition in N2 atmosphere for europium to dysprosium, ytterbium and yttrium compounds up to 1000°C were the respective oxides Ln2O3 (Ln=Eu, Gd, Tb, Dy, Yb, Y) while for lanthanum, cerium praseodymium, neodymium, samarium, holmium, erbium, thulium and lutetium compounds, the mass loss is still being observed up to 1000°C. In CO2 atmosphere, the final residue up to 1000°C for all the compounds was the respective oxides, CeO2, Tb4O7 and Ln2O3 (Ln=La, Pr to Gd, Dy to Lu and Y).