Многоядерные гетерометаллические (Y или Ln, Ba, Cu)-содержащие ацетилацетонаты как исходные вещества для получения ВТСП оксидов LnBa2Cu3O7-б

Abstract

Multinuclear heterometallic (Y or Ln, Ba, Cu)-containing acetylacetonates having a stoichiometric ratio between the cations Cu : Ba : Ln = 3 : 2 : 1 have been synthesized. The complexes are individual compounds and form an isostructural series with Ln = Y, La, Nd, Sm, Gd, Tb, Dy, Ho, Yb. The powder diffraction patterns have been indexed in the framework of the tetragonal system with the subcell parameters а sub = 11.48, с sub = 9.37 А. Conclusions regarding the multinuclear structure of the complexes, which contain exchange-coupled copper(II) ions, acetylacetonate ions performing the role of bidentate chelating ligands, and bridging alkoxo groups, have been drawn on the basis of data from magnetochemistry, as well as IR and ESR spectroscopy. All the compounds investigated are characterized by an identical pattern of thermal transformations in the 20-500 С range. The phase composition of the pyrolysis products of the complexes obtained in different stages of heating up to 1000 С has been investigated by X-ray diffraction analysis, and it has been shown that the final substances are practically phase-pure ternary oxides with a structure of the YBa2Cu3O7-б type