title: Ferromagnetic Interactions in Highly Stable, Partially Reduced TiO2: The S=2 State in Anatase.
abstract: We report direct evidence for quintuplet spin states in a particular kind of reduced TiO2anatase obtained by the mild oxidation of TiB2under hydrothermal conditions. Continuous-wave and pulse EPR spectroscopy at X and Q band frequencies provide compelling evidence for the presence of S=2 states, stable in a wide range of temperatures up to room temperature. A tentative model, corroborated by spin-polarized DFT calculations, is proposed, which consists of four ferromagnetically interacting Ti3+ions with distances ranging from 0.5 nm to 0.8 nm and tetrahedral arrangement.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Torino, Via Giuria 7, 10125, Torino, Italy.
authors.forename: Mario
authors.identifier: 0000-0001-8128-8031
authors.initials: M
authors.lastname: Chiesa
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Torino, Via Giuria 7, 10125, Torino, Italy.
authors.forename: Stefano
authors.initials: S
authors.lastname: Livraghi
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Torino, Via Giuria 7, 10125, Torino, Italy.
authors.forename: Elio
authors.initials: E
authors.lastname: Giamello
authors.affiliation: Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Via Cozzi 55, Milano, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Albanese
authors.affiliation: Dipartimento di Scienza dei Materiali, Università di Milano Bicocca, Via Cozzi 55, Milano, Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Pacchioni
keywords: EPR spectroscopy; TiO2; ferromagnetism; nanomaterials