A THERMAL STUDY OF SEVERAL LANTHANIDE TRIFLATES

Five lanthanide triflates, Ln(TfO)(3). nH(2)O, where TfO- = CF3SO3-, L n = La3+, Nd3+, Sm3+, Gd3+ and Yb3+, and n = 9 and 13, have been prepa red and the thermal decomposition processes of these triflates up to 6 00 degrees C were characterized by means of TG, DTA, XRD. The thermal studies have shown almost all the lanthanide triflates prepared in thi s study to exist as a stable nonahydrate. During the stepwise dehydrat ion processes, it was found that mono-, di-, tri-, penta-, and heptahy drates were formed. Decompositions were found to be exothermic, and ca lcinations of these triflates at 600 degrees C resulted in the formati on of the corresponding LnF(3). Crystal systems of the trifluorides th us obtained were hexagonal for La, Nd and Sm trifluorides, whereas tho se of Gd and Yb were found to be orthorhombic. The volatile decomposit ion products at 600 degrees C were identified by MS, and it was reveal ed that the over all reaction scheme for the thermal decomposition pro ceeds as follows: Ln(OTf)(3)-->LnF(3) + 3SO(2) + CO2 + CF3OCF3. (C) 19 98 Elsevier Science Ltd. All rights reserved.