Synthesis and thermal behavior of [Li(thf)3(μ-Cl)La{N(SiMe3)2}3] and its investigation as spin-coating precursor for lanthanum-based layer formation

Abstract

The lanthanum(III) complex [Li(thf)3(μ-Cl)La{N(SiMe3)2}3] (3) was obtained by the reaction of LaCl3 with three equiv of Li[N(SiMe3)2]3 in a tetrahydrofuran solution. The molecular structure of 3 in the solid state was characterized by a tetracoordinated anionic lanthanide(III) amide in form of an adduct with LiCl(thf)3 as evidenced by single crystal X-ray structure analysis. In order to study the suitability of 3 as a precursor for the deposition of La2O3/LiLaSiO4 by thin layer deposition techniques, its thermal behavior was investigated by thermogravimetry (TG) and TG-MS-coupled studies. TG studies show a two-step decomposition process, whereby volatile decomposition products can be detected during the second decomposition step. TG measurements under an atmosphere of oxygen produced La2O3. Calcination processes of 3 under ambient atmosphere for 10 h at 1000 °C gave La2O3 and LiLaSiO4, which was confirmed by PXRD studies. Metal-organic 3 was applied as spin-coating precursor for La2O3 thin film formation giving the as-deposited layers nearly crack-free.