Local order in titania polymorphs

Crystalline structure local order of titania polymorphs, brookite, anatase and rutile is described with a representative octahedron for each phase. The detailed analysis of the atomic bond lengths forming these octahedra helps to understand the macroscopic properties observed in these materials. In rutile samples with an average crystal size between 9.77(9) and 149(2) nm , these lengths did not depend on the crystal size. This behavior is not necessarily similar for anatase and brookite, which have crystalline structures with lower symmetry. The dependence of anatase on rutile in synthesis conditions suggests that atom bond lengths in this titanium polymorph depend on crystal size. Brookite is stabilized with copper and chloride ions. Anatase open crystalline structure can dissolve cations and anions that stabilize it at high temperatures, or can be used as precursors for preparing titanates at low temperatures. Rutile, which is normally obtained after annealing brookite and anatase at high temperatures, can be synthesized at low temperatures in the presence of platinum or tin ions during synthesis or by using TiCl 3 as precursor

Sol-gel titania modified with Ba and Li atoms for catalytic combustion

Samples of compounds in the ternary system BaO-Li2O-TiO2 were synthesized by using the sol-gel method at pH 3 and pH 9, and the calcination temperatures of 600 and 800degreesC in the region of solid solutions which can form the "ideal" composition Ba3Li2Ti8O20. The X-ray diffraction patterns of the samples showed a mixture of three crystalline phases, the main one was isostructural with the ternary phase Ba3Li2Ti8O2

Ophthalmic manifestations in Mexican patients with Fabry disease [Manifestaciones oftalmológicas en pacientes mexicanos con enfermedad de Fabry]

Al2O3 was synthesized by the sol-gel method, dried at 100 C and annealed at 400, 500, 600 and 700 C, respectively. These materials were characterized and evaluated to be used as photocatalysts for the degradation of phenol in aqueous phase. Although Al2O3 is a well-known insulator, in the present study we show the feasibility of using Al2O3 synthesized by the sol-gel method as a catalyst for the photomineralization of hazardous organic molecules. The photocatalytic activity of these materials was higher than that of Degussa P-25 TiO 2, and other commercial aluminas tested, particularly in the case of the sample of Al2O3 calcined at 400 C. The results of Nuclear Magnetic Resonance of solids (27AlMAS NMR) indicate that Al changes its coordination number during the calcination process. Rietveld refinement of the X-ray diffraction patterns denotes a notable hydroxylation in the Al 2O3 structure, which was not removed by thermal treatments. Complementary spectroscopic studies (UV-Vis and FTIR) as well as the characterization of the textural properties are reported. It is proposed that UV irradiation of the hydroxylated Al2O3 induces an effective separation of the electron-hole pairs and hence, promotes the photodegradation of phenolic compounds. " 2013 Elsevier B.V. All rights reserved.",,,,,,"10.1016/j.cattod.2013.10.027",,,"http://hdl.handle.net/20.500.12104/42008","http://www.scopus.com/inward/record.url?eid=2-s2.0-84889651273&partnerID=40&md5=1ccf3efc9224f48c1d77dd5c233e5362",,,,,,,,"Catalysis Today",,"4