Molecular structure design of single source precursors and multivariate analysis of their evaporation in dynamic vacuum using El-Mass spectrometry. An approach to Barium-Strontium Titanate-Niobate as a case study

Preparation of high purity dense coatings of perovskite materials, in particular (Ba,Sr)TiO3 and Ba(Ti,Nb)03, requires application of highly solution and even gas phase stable single-source precursors. We report here a new series of bimetallic alkoxide complexes of 1: 1 composition, M-II M-2(2)V(L)(2)(OEt)(12)(EtOH)(n), M-11=Sr, Ba, M-v=Nb, Ta, L=2,2,6,6-tetramethylheptanedionate (thd, n=2) or isopropylacetoacetate ((PrAcAc)-Pr-1, n=0). These products were characterized by X-ray single crystal study in the solid state for the Sr2Ta2(thd)(2)(OEt)(12)(EtOH)(2) as an example, and for all complexes by NMR in solution. Multivariate analysis of evaporation of these complexes by El-mass spectrometry shows that they are transformed into gas phase in the molecular form and display high gas phase stability. TG measurements reveal them to be thermally stable up to at least 280 degrees C and decompose at higher temperatures in a single step without separation of the components. The precursor transformations in solutions (through microhydrolysis) have also been studied. (C) 2007 Elsevier B.V All rights reserved.