02203nas a2200253   4500008004100000022001400041245008000055210006900135260007300204300001000277490000800287520136700295653001201662653001001674653002401684653001101708653003401719653001201753100001901765700002001784700001801804700002001822856010701842       2005                        eng d  a0040-603100aCharacterization of nanocrystalline anatase titania: an in situ HTXRD study0 aCharacterization of nanocrystalline anatase titania an in situ H  aPO BOX 211, 1000 AE AMSTERDAM, NETHERLANDSbELSEVIER SCIENCE BVcMAR  a37-410 v4273 a<p>Nanocrystalline titania was synthesized by the hydrolysis of titanium iso-propoxide using ultrasonication. The powder XRD patterns of the sample were recorded in static air and vacuum using a Philips X-pert Pro diffractometer equipped with a high-temperature attachment (HTK16) from room temperature (298 K) to 1173 K and were analyzed by the Rietveld refinement technique. The anatase to rutile phase transformation was observed at 1173 K for the data collected in static air. Only 3% of anatase titania transformed to rutile when the experiments were carried out at H 73 K in vacuum. The phase transformation from anatase to rutile is accompanied by a continuous increase in the crystallite size of the anatase phase from 9 nm at room temperature to 28 nm at 873 K and then to 50 nm at 1173 K in air while the process of crystallite growth was suppressed in vacuum. A linear increase in the unit cell parameters `a' and `c', and thus, an overall linear increase in the unit cell volume was observed as a function of temperature in static air as well as vacuum. The lattice and volume thermal expansion coefficients (TEC), alpha(a), alpha(c), and alpha(v) at 873 K are 8.57 x 10(-6), 8.71 x 10(-6) and 25.91 x 10(-6) K-1 in air and 18.01 x 10(-6), 14.95 x 10(-6) and 51.13 x 10(-6) K-1 in vacuum, respectively. (C) 2004 Elsevier B.V. All rights reserved.</p>10aAnatase10aHTXRD10aRietveld refinement10arutile10athermal expansion coefficient10atitania1 aJagtap, Neelam1 aBhagwat, Mahesh1 aAwati, Preeti1 aRamaswamy, Veda  uhttps://library.ncl.res.in/content/characterization-nanocrystalline-anatase-titania-situ-htxrd-study-0