title: Halogen- and acid-free syntheses of TiO2 nanocrystal coatings and high surface area TiO2 nanocrystal-assembled particles.
abstract: Halogen- and acid-free aqueous solutions were developed to synthesize TiO2 nanocrystal coatings and high surface area TiO2 nanocrystal-assembled particles. Fluorine doped tin oxide substrates were covered with TiO2 nanocrystal coatings in the solutions containing titanium(IV) potassium oxalate, 2-hydrate (K2[TiO(C2O4)2] x 2H2O) at 90 degrees C for 3 days. The substrates changed color by the coatings. The nanocrystals were about 10-50 nm in size. They connected with the substrates strongly due to direct nucleation and crystallization on the substrates. Furthemore, TiO2 particles were synthesized from the solutions at 90 degrees C for 3 days. They were assemblies of TiO2 nanocrystals. Brunauer-Emmett-Teller surface area reached to 275 m2/g. Nanospaces were formed by assembly of the nanocrysrtals. They contributed high surface area. Halogen- and acid-free aqueous solution processes had advantages of low environmental load and safety manufacturing environment. Harmless TiO2 coatings and particles can be applied to medical applications, medicines, cosmetics, food additives, etc.
authors.forename: Yoshitake
authors.initials: Y
authors.lastname: Masuda
authors.forename: Kazumi
authors.initials: K
authors.lastname: Kato
mesh_terms: D000143:Acids / Q000737:chemistry; D000268:Adhesiveness; D003460:Crystallization; D005461:Fluorine / Q000737:chemistry; D006219:Halogens / Q000737:chemistry; D008855:Microscopy, Electron, Scanning; D015336:Molecular Probe Techniques; D053758:Nanoparticles / Q000737:chemistry*; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors; D014025:Titanium / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D000143:Acids; D006219:Halogens; C009495:titanium dioxide; D005461:Fluorine; D014025:Titanium