Comparison of thermal properties of lanthanide trimellitates prepared by different methods

By diffusion in gel medium new complexes of formulae: Nd(btc).6H(2)O, Gd(btc)-4.5H(2)O and Er(btc)-5H(2)O (where btc= (C6H3 (COO)(3)(3)) were obtained. Isomorphous compounds were crystallized in the form of globules. During heating. 3 g, in air atmosphere they lose stepwise water molecules and then anhydrous complexes decompose to oxides. Hydrothermally synthesized polycrystalline lanthanide trimellitates form two groups of isomorphous compounds. The light lanthanides form very stable compounds of the formula Ln(btc)-nH(2)O (where Ln=Ce-Gd and n=0 for Ce: n=1 for Gd; n=1.5 for La, Pr, Nd; n=2 for Eu, Sm). They dehydrate above 250 degrees C and then immediately decomposition process occurs. Heavy lanthanides form complexes of formula Ln(btc)-nH(2)O (Ln=Dy-Lu). For mostly complexes, dehydration occurs in one step forming stable in wide range temperature compounds. As the final products of thermal decomposition lanthanide oxides are formed.