27 research outputs found
Synthesis of advanced ceramics by hydrothermal crystallization and modified related methods
The synthesis, structural characterization, magnetochemistry and Mössbauer spectroscopy of [Fe3LnO2(CCl3COO)8H2O(THF)3] (Ln = Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Lu and Y)
The new tetranuclear complexes [Fe3Ln(l3-O)2(CCl3COO)8(H2O)(THF)3]THF (Ln = CeIII (1), PrIII (2), NdIII(3)) and [Fe3Ln(l3-O)2(CCl3COO)8(H2O)(THF)3]THFC7H16 (Ln = SmIII (4), EuIII (5), GdIII (6), TbIII (7), DyIII (8), HoIII (9), LuIII (10) and YIII (11)) have been prepared. All compounds were prepared by the reaction between [Fe2BaO(CCl3COO)6(THF)6] and the corresponding LnIII nitrate salt. The crystal structures of 1â4, 8 and 9 have been determined; these isostructural molecules have a non-planar {Fe3Ln(l3-O)2} ââbutterflyâ core. Magnetic susceptibility measurements show dominant intramolecular antiferromagnetic exchange interactions for all the complexes. 57Fe Mössbauer spectroscopy shows three different environments for the FeIII metal ions, all in their high-spin state S = 5/2 (confirming that no electron transfer from CeIII to FeIII occurs in 1). At the time scale of the Mössbauer spectroscopy (about 107 s), evidence of magnetization blocking, i.e. slow relaxation of the magnetization, is observed below 3 K for 7, which was confirmed by ac susceptibility measurements