Barium and titanium aryl oxides as precursors for the preparation of thin-film oxides. The effect of bombardment by O2+

Abstract

A set of barium aryl oxides of composition [Ba(OC₆H₂Bu^t₂-2,6-X-4)₂(thf)_n](X = H 1, Me 2, OMe 3 or Bu^t4; thf = tetrahydrofuran) has been prepared together with the related adducts [Ba(OC₆H₂Bu^t₂-2,6-X-4)₂{P(NMe₂)₃O}₂](X = H 5 or Me 6), which can be obtained by treating compounds 1 and 2 with neat P(NMe₂)₃O respectively. X-Ray studies showed that 6 has a distorted-tetrahedral structure, with the two Ba–O bonds to the aryl oxide ligands somewhat shorter than those to the P(NMe₂)₃O groups [2.414(8)vs. 2.579(8)Å]. Samples of complex 4 and [Ti(OC₆H₃Prⁱ₂-2,6)₄], respectively, and a third homogeneous sample obtained by mixing equimolar amounts of these have been subjected to bombardment by Ar⁺ and O₂⁺ ions of relatively low energy (3.5 keV) and the ensuing transformation investigated by X-ray photoelectron spectroscopy. No significant variation of the C/M ratio was observed when employing Ar⁺ ions, but O₂⁺ produced a remarkable decrease in the carbon content which leads eventually to the formation of inorganic compounds, BaCO₃, TiO₂ and BaTiO₃, respectively, for the three samples. Action of oxygen plasma on the titanium aryl oxide did not result in a marked decrease in the C/M ratio, but it produced instead high concentrations of carbon- and oxygen-containing species.