| The synthesis and characterization of six fluorine-free barium MOCVD (metal-organic chemical vapor deposition) precursors based upon encapsulating {dollar}beta{dollar}-ketoiminate-polyether ligation and having the general formula Ba(RCOCHC(NR{dollar}spprime){dollar}R{dollar}sp{lcub}primeprime{rcub})sb2{dollar} (R{dollar}spprime{dollar} = {dollar}sp{lcub}rm t{rcub}{dollar}butyl, R{dollar}spprime{dollar} = polyether, and R{dollar}sp{lcub}primeprime{rcub}{dollar} = methyl or {dollar}sp{lcub}rm t{rcub}{dollar}butyl) is reported. The complexes were prepared by a nonaqueous approach which employs BaH{dollar}sb2{dollar} and the corresponding {dollar}beta{dollar}-ketoimine. These complexes have been characterized by {dollar}sp1{dollar}H and {dollar}sp{lcub}13{rcub}{dollar}C NMR spectroscopy, elemental analysis, mass spectroscopy, cryoscopic molecular weight determination, thermogravimetric analysis, and single crystal X-ray structural analysis. These complexes serve as volatile barium MOCVD precursors. Thus, BaPbO{dollar}sb3{dollar} films have been grown using the aforementioned barium {dollar}beta{dollar}-ketoiminate complexes and Pb(dipivaloylmethanate){dollar}sb2{dollar} as the respective barium and lead sources, and have been characterized by X-ray diffraction, scanning electron microscopy energy dispersive X-ray spectroscopy, and variable-temperature resistivity measurements. Investigation of thermolytic decomposition of the barium {dollar}beta{dollar}-ketoiminate complexes led to identification of 2-methyl-4-{dollar}sp{lcub}rm t{rcub}{dollar}butylpyridine (17), pinacolone, and 2,2-dimethyl-5-imino-3-hexanone as the major organic thermolysis products of 11, 12, and 13.; The MOCVD synthesis of Tl-Ba-Ca-Cu-O thin films on novel substrates, a growth method and film configuration which is potentially applicable toward device technologies, has been investigated. These films were prepared in three steps: first, deposition of Ba-Ca-Cu-O-(F) thin films by MOCVD; next, defluorination via water/oxygen anneal; and finally, thallination using volatile thallium oxides. Films were characterized by X-ray diffraction {dollar}(theta/2theta,{dollar} {dollar}omega,{dollar} and {dollar}phi{dollar} scans), variable temperature magnetization, variable temperature conductivity, and scanning and transmission electron microscopy. Attempts at preparing Tl-Ba-Ca-Cu-O thin films on Pt resulted in the formation of {dollar}rm Tlsb2Ptsb2Osb7{dollar} while attempts using Ag substrate led to the formation of a non-contiguous Ba-Ca-Cu-O film during the thallination step. {dollar}rm Tlsb2Basb2Casb1Cusb2Osb{lcub}x{rcub}{dollar} on Au/YSZ, Au, and LaAlO{dollar}sb3{dollar} show preferential orientation of crystallite c-axes and exhibit T{dollar}sb{lcub}rm c{rcub}{dollar} equal to 94, 80, and 97 K, respectively. Au-Cu alloy formation was confirmed by TEM/EDS for {dollar}rm Tlsb2Basb2Casb1Cusb2Osb{lcub}x{rcub}{dollar} thin films on Au. |
