Heterobimetallic copper–barium complexes for deposition of composite oxide thin films

Abstract

Heterobimetallic molecular precursors [Ba(dmap)₄Cu₄(OAc)₆·THF] (1) and [Ba(dmap)₄Cu₄(TFA)₆·THF] (2) [dmap = N,N-dimethylaminopropanolate, OAc = acetate and TFA = trifluoroacetate] for the deposition of barium–copper composite oxide thin films, were prepared by the interaction of Ba(dmap)₂ with Cu(OAc)₂ for 1 and Cu(TFA)₂ for 2, in THF. Both heterobimetallic complexes were characterized by melting point, elemental analysis, FT-IR spectroscopy, mass spectrometry and single crystal X-ray diffraction. X-Ray crystallography shows that complex 1 crystallizes in the orthorhombic space groupP2₁2₁2₁ with the cell dimensions a = 11.2621(11) Å, b = 18.2768(17) Å and c = 24.541(2) Å, while complex 2 crystallizes in the monoclinic space groupC2/c with a = 23.9288(14) Å, b = 19.8564(12) Å, c = 25.5925(15) Å and β = 112.4390(10)°. Thermal gravimetric analysis shows that both complexes 1 and 2 undergo controlled thermal decomposition at 450 °C and 400 °C, respectively, to give mixed metal oxide composite thin films. Scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and X-ray powder diffraction (XRD) analyses of the thin films suggest the formation of good quality crystalline thin films of BaCuO₂–CuO composites from both 1 and 2, with average grain sizes of 105 to 175 nm and 110 to 205 nm, respectively.