title: Energetics of nanocrystalline TiO2.
abstract: The energetics of the TiO(2) polymorphs (rutile, anatase, and brookite) were studied by high temperature oxide melt drop solution calorimetry. Relative to bulk rutile, bulk brookite is 0.71 +/- 0.38 kJ/mol (6) and bulk anatase is 2.61 +/- 0.41 kJ/mol higher in enthalpy. The surface enthalpies of rutile, brookite, and anatase are 2.2 +/- 0.2 J/m(2), 1.0 +/- 0.2 J/m(2), and 0.4 +/- 0.1 J/m(2), respectively. The closely balanced energetics directly confirm the crossover in stability of nanophase polymorphs inferred by Zhang and Banfield (7). An amorphous sample with surface area of 34,600 m(2)/mol is 24.25 +/- 0.88 kJ/mol higher in enthalpy than bulk rutile.
authors.affiliation: University of California, Department of Chemical Engineering and Materials Science, Thermochemistry Facility, Davis, CA 95616, USA.
authors.forename: M R
authors.initials: MR
authors.lastname: Ranade
authors.forename: A
authors.initials: A
authors.lastname: Navrotsky
authors.forename: H Z
authors.initials: HZ
authors.lastname: Zhang
authors.forename: J F
authors.initials: JF
authors.lastname: Banfield
authors.forename: S H
authors.initials: SH
authors.lastname: Elder
authors.forename: A
authors.initials: A
authors.lastname: Zaban
authors.forename: P H
authors.initials: PH
authors.lastname: Borse
authors.forename: S K
authors.initials: SK
authors.lastname: Kulkarni
authors.forename: G S
authors.initials: GS
authors.lastname: Doran
authors.forename: H J
authors.initials: HJ
authors.lastname: Whitfield