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Ferromagnetic Interactions in Highly Stable, Partially Reduced TiO 2 : The S= 2 State in Anatase
Author(s) -
Chiesa Mario,
Livraghi Stefano,
Giamello Elio,
Albanese Elisa,
Pacchioni Gianfranco
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201610973
Subject(s) - anatase , electron paramagnetic resonance , ferromagnetism , hydrothermal circulation , spectroscopy , materials science , tetrahedron , spin states , ion , spins , spin (aerodynamics) , chemical physics , range (aeronautics) , crystallography , condensed matter physics , chemistry , inorganic chemistry , nuclear magnetic resonance , chemical engineering , physics , photocatalysis , thermodynamics , biochemistry , organic chemistry , quantum mechanics , engineering , composite material , catalysis
We report direct evidence for quintuplet spin states in a particular kind of reduced TiO 2 anatase obtained by the mild oxidation of TiB 2 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 Ti 3+ ions with distances ranging from 0.5 nm to 0.8 nm and tetrahedral arrangement.