Apparent magic numbers in embedded Ti-O clusters
Résumé
Stable clusters constituted of four TiO2 entities have been evidenced in nanometer-sized spinel oxides by a combination of diffraction and x-ray-absorption expts. Contrary to free clusters, the size of the embedded clusters is strongly detd. by the constraints imposed by the surrounding matrix so that the magic no. of four is in fact specific to the matrix and only then apparent.