Abstract

The heterometal alkoxides Sr[Ta(OPrⁱ)₆]₂·2PrⁱOH 1 and Mg[Nb(OEt)₆]₂·2EtOH 2 have been structurally characterised by X-ray diffraction. Compound 1 is a precursor for the deposition of strontium bismuth tantalate (SrBi₂Ta₂O₉) by metalorganic chemical vapour deposition (MOCVD), whilst 2 is a potential precursor for the MOCVD of lead magnesium niobate [Pb(Mg_0.33Nb_0.66)O₃]. In this paper it is shown how the presence of Pb(thd)₂ (thd = 2,2,6,6-tetramethylheptane-3,5-dionate) significantly influences the deposition chemistry of 2. In the absence of Pb(thd)₂ and at low substrate temperatures (ca. 425 °C) the Mg∶Nb ratio in the oxide film grown from 2 is close to 1∶2, whereas at higher substrate temperatures (600 °C) the films are magnesium deficient, indicating partial decomposition of 2. However, in the presence of Pb(thd)₂ films grown from 2 at low temperature (425–500 °C) contain no detectable Mg whilst the 1∶2 Mg∶Nb ratio, required in Pb(Mg_0.33Nb_0.66)O₃, is now obtained at higher substrate temperatures (600 °C). This is attributed to the formation of a thermally stable Mg β-diketonate species via a gas-phase ligand exchange reaction between Pb(thd)₂ and 2.