Titanium surface characteristics

Finally, we mention studies of the rutile SnO2(110) surface [145,164-166]. Despite the absence of partially filled d orbitals on Sn cations, the surface characteristics of Sn02 are qualitatively similar to those of Ti02- The same is true for the non-stoichiometric (1 x 1) and (1 X 2) surfaces, which present a distribution of defect states in the gap [166]. The authors, however, argue that some quantitative differences with respect to Ti02 take place, which are due to the much larger polarisability of the Tin atoms, compared to the Titaniums. 

Tamagawa, Y., and Horikawa, H. (2011) Surface characteristics of titanium oxide... 

An YB, Oh NH, Chun YW, Kim YH, Park JS, Choi KO et al (2005) Surface characteristics of porous titanium implants fabricated by environmental electro-discharge sintering of spherical Ti powders in a vacuum atmosphere. Scripta Mater 53 905-908... 

K. Imamura, Y. Kawasaki, T. Nagayasu, T. Sakiyama, and K. Nakanishi, Adsorption Characteristics of Oligopeptides Composed of Acidic and Basic Amino Acids on Titanium Surfaces, J. BioscL Bioeng., 103, 7-12 (2007). 

FTIR spectroscopy has proven to be particularly useful in gaining an understanding of the biocompatibility phenomenon. It is believed [746, 841, 856, 857] that protein adsorption is the initial step in the interaction of blood with implanted biomaterials, followed by adhesion of cells and subsequent tissue attachment. This implies that the substrate surface characteristics influence the process, which was confirmed by ATR studies of albumin adsorption on calcium phosphate bioceramics and titanium [763] and segmented polyurethane [764], albumin and fibrinogen on acetylated and unmodified cellulose [765, 766], poly(acrylic acid)-mucin bioadhesion [767], polyurethane-blood contact surfaces [768], and other proteins on poly(ester)urethane [769], polystyrene [767, 771] and poly(octadecyl methacrylate) [771] and by IRRAS study of adsorption of proteins on Cu [858]. Another branch of IR spectroscopic studies of protein adsorption relates to microbial adhesion (Section 7.8.3). 

Falaras P (1998) Synergetic effect of carboxylic acid functional groups and fi actal surface characteristics for efficient dye sensitization of titanium oxide. Sol Energy Mater Sol Cells 53 (1-2) 163-175... 

Contact with steel, though less harmful, may accelerate attack on aluminium, but in some natural waters and other special cases aluminium can be protected at the expense of ferrous materials. Stainless steels may increase attack on aluminium, notably in sea-water or marine atmospheres, but the high electrical resistance of the two surface oxide films minimises bimetallic effects in less aggressive environments. Titanium appears to behave in a similar manner to steel. Aluminium-zinc alloys are used as sacrificial anodes for steel structures, usually with trace additions of tin, indium or mercury to enhance dissolution characteristics and render the operating potential more electronegative. 

The spectra of the oxide surface prior to metal deposition Is characteristic of fully oxidized titanium. In the region just below 435 eV the llneshape Is significantly different for different oxides of titanium (15). 

Titanium dioxide differs from silica mainly in two respects (1) the Ti + ions are octahedrally coordinated in all three modifications of TiOji (2) the Ti—0 bond is more pronouncedly ionic than the Si—O bond. Using Pauling s electronegativity values (297), one calculates a 63% ionic character for the Ti—0 single bond versus 50% for Si—O. In SiOj, there is certainly some double bond character involving 3d orbitals of the Si atom, causing lowered ionic character. Therefore, characteristic differences should be expected regarding the surface chemistry. 

The tetrahedral structure of these surface alkyl complexes on MCM-41(5oo) has been highlighted by XANES a sharp, intense pre-edge peak at 4969.6 0.3 eV is characteristic of an electronic transition of titanium, from the Is energetic level to molecular orbitals mixing 3d and 4p of Ti with the orbitals of the Ugands, in a complex where titanium is in a tetrahedral symmetry [28-31]. The same argument can be applied for species obtained from alcoholysis of 2a and 2b, especially using tert-butanol. 

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