Synthesis, characterization and thermal analysis of solid-state lanthanide mandelates in CO2 and N2 atmospheres.

Abstract

Solid-state Ln-L compounds, where Ln stands for trivalent lanthanides and L is mandelate (C 6 H 5 CH(OH)CO 2 -) have been synthesized. Elemental analysis, complexometry, infrared spectroscopy (FTIR), simultaneous thermogravimetry and differential thermal analysis (TG-DTA), simultaneous thermogravimetry and differential scanning calorimetry (TG-DSC) coupled to FTIR have been used to characterize and to study the thermal stability and thermal decomposition of these compounds in CO 2 and N 2 atmospheres. In both atmospheres, the dehydration of the lanthanum, cerium and samarium to lutetium compounds occurs in a single step, while for praseodymium and neodymium ones the dehydration occurs in two consecutive steps. The thermal decomposition of the anhydrous compounds occurs in several consecutive and / or overlapping steps with the formation of CeO 2 , Pr 6 O 11 , Tb 4 O 7 and Ln 2 O 3 (Ln = La, Nd, Sm to Gd and Dy to Lu) in dynamic CO 2 atmosphere or CeO 2 and Ln 2 O 3 (Ln = La, Pr to Lu) in dynamic N 2 one, as final residue.