Implications for the thin-film densification of TiO{sub 2} from carboxylic acid-modified titanium alkoxides. Syntheses, characterizations, X-ray structures of Ti{sub 3}({mu}{sub 3}-O)(O{sub 2}CH){sub 2}(ONep){sub 8}, Ti{sub 3}({mu}{sub 3}-O)(O{sub 2}CMe){sub 2}(ONep){sub 8}, Ti{sub 6}({mu}{sub 3}-O){sub 6}(O{sub 2}CCHMe{sub 2}){sub 6}(ONep){sub 6}, [Ti({mu}-O{sub 2}CCMe{sub 3})(ONep){sub 3}]{sub 2}, and Ti{sub 3}({mu}{sub 3}-O)(O{sub 2}CCH{sub 2}CMe{sub 3}){sub 2}(ONep){sub 8}(ONep = OCH{sub 2}CMe{sub 3})
Carboxylic acid (HORc)-modified Ti(OR){sub 4} products were used to study the effect that similarly ligated species with substantially varied structures have on the final densification of the resultant ceramic (in this case TiO{sub 2}). The 1:1 stoichiometric products isolated from the reactions of [Ti({mu}-ONep)(ONep){sub 3}]{sub 2} (1, ONep = OCH{sub 2}CMe{sub 3}) and a variety of sterically hindered carboxylic acids [HORc: HOFc (HO{sub 2}CH), HOAc (HO{sub 2}CCH{sub 3}), HOPc (HO{sub 2}CCHMe{sub 2}), HOBc (HO{sub 2}CCMe{sub 3}), or HONc (HO{sub 2}CCH{sub 2}CMe{sub 3})] were identified by single-crystal X-ray diffraction and solid-state {sup 13}C MAS NMR spectroscopy at Ti{sub 3}({mu}{sub 3}-O)(OFc){sub 2}(ONep){sub 8} (2), Ti{sub 3}({mu}{sub 3}-O)(OAc){sub 2}(ONep){sub 8} (3), Ti{sub 6}({mu}{sub 3}-O){sub 6}(OPc){sub 6}(ONep){sub 6} (4), Ti{sub 2}({mu}-OBc){sub 2}(ONep){sub 6} (5), and Ti{sub 3}({mu}{sub 3}-O)(ONc){sub 2}(ONep){sub 8} (6). Compounds 2, 3, and 6 adopt a triangular arrangement of Ti atoms linked by a {mu}{sub 3}-oxide moiety with ORc and ONep ligands supporting the basic framework. Compound 4 adopts a distorted, hexagon-prism geometry of two offset [Ti-O-]{sub 3} rings with each six-coordinated metal possessing a terminal ONep and two monodentate OPc ligands. The unique, nonesterified product 5 is dimeric with two {mu}-ONep, two unidentate bridging OBc, and two terminal ONep ligands. The solution behaviors of 2--6 were investigated by NMR experiments and were found to retain the solid-state structure in solution with a great deal of ligand rearrangement. Films of TiO{sub 2} were made from redissolved crystals of 2--6. The highest density TiO{sub 2} thin films were derived from the partially hydrolyzed, trinuclear, low-carbon-containing ONep complexes 2 and 3, as determined from ellipsometric data.
- Research Organization:
- Sandia National Lab., Albuquerque, NM (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC04-94AL85000
- OSTI ID:
- 20017322
- Journal Information:
- Journal of the American Chemical Society, Vol. 121, Issue 51; Other Information: PBD: 29 Dec 1999; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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