Molecular Precursors of Mixed Oxide Materials for Sensor Applications and Molecular Imaging

Cation-doped perovskite materials based oil barium titanate, such as (Ba,Sr)(Ti,Nb)O-3, are of interest as transparent ceramic semiconductors with conductivity strongly dependent both on the cation and the oxygen stoichiometry. Development of precursor systems offering proper control over the cation stoichiometry and permitting to efficiently avoid residual carbon impurities is therefore an important problem. In the present communication we report the synthesis and structural characterization of a series of hetero-metallic precursors of these materials with the general formulae (M2Ti2)-Ti-II(L)(4)(OR)(8)(ROH)(2) and (M2M2V)-M-II(L)(2)(OR)(12)(ROH)(2), where R = Et, Pr-n; M-II = Ba, Sr; M-V = Nb, Ta; L = the or R'OAcAc (R' = (BU)-B-t, Pr-i). The compounds have been characterized by single crystal and power X-ray and by H-1 and C-13 NMR, vibration spectroscopy and mass-spectrometry. These species are very stable in solution and display even considerable gas phase stability. Solution microhydrolysis of the molecules ill these series leads most often to oxo-aggregates with the cation stoichiometry rather close to 1: 1, which additionally simplifies handling Of Solutions based oil these precursors. The obtained precursors have been used for preparation of powders and films (oil Si Substrates), which were characterized by SEM-EDS and X-ray powder techniques.