We are studying arrayed nanoclusters stabilized in porous crystals of zeolites by a wide variety of measurements, such as wide range optical spectroscopy, magnetic measurement, electron spin resonance, MuSR, electric transport, etc. In zeolite crystals, such as A and X, nano-cages with internal diameters of 11 and 13 Å are arrayed in simple cubic and diamond structures, respectively. By the loading of guest alkali metal into the nanocages, the s-electrons of alkali atoms are made to successively occupy 1s, 1p and 1d quantum electronic states of the clusters. New electronic states like super atoms are formed. Novel electronic properties, such as ferromagnetism of s-electrons and metal-insulator transition are observed. These phenomena are explained by the mutual interaction of arrayed clusters, the orbital degeneracy, electron correlation, etc. Amazingly, ferromagnetic properties are found in non-magnetic elements introduced into the nanospace of zeolites crystals.
Schematic illustration of clusters arrayed in
zeolite A crystals
Quantum states of s-electrons in nanoclusters