Ferromagnetic Interactions in Highly Stable, Partially Reduced TiO2 : The S=2 State in Anatase
Mario Chiesa1, Stefano Livraghi1, Elio Giamello1
1Dipartimento di Chimica, Università degli Studi di Torino, Via Giuria 7, 10125, Torino, Italy.
Abstract:
We report direct evidence for quintuplet spin states in a particular kind of reduced TiO2 anatase obtained by the mild oxidation of TiB2 under 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.
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