Structural phase stability of Se clusters in zeolites

Phase transition in confined Se nanoclusters

“…The crystallized cluster has been proved to be of trigonal form (t-Se), which is stable at ambient. And the crystallization temperature for bulk a-Se is about 380 K. 16 We observed similar crystallization process for the a-Se in the mesopores; the Raman intensity of t-Se increases and the intensity of a-Se decreases. The crystallization temperature is determined quantitatively.…”

Optical Properties of Selenium Clusters/Particles Incorporated into Porous Materials

“…However, all of the optical gaps of Se clusters in zeolites are larger than that of bulk a-Se whose structure is believed to be composed of a mixture of ring-and chain-like segments. In addition, the local structural units of Se clusters in the FAU zeolites are similar to that of bulk a-Se except for the absence of inter-molecular (ring or chain) interaction [10]. Therefore, we infer that the electronic states of Se clusters in zeolites are not only governed by the local structure of the clusters, but also modulated by the absence of inter-molecular (ring or chain) interaction, and influenced by the interaction between lone pair electrons of Se clusters and cations of the framework of zeolites.…”

“…ahn versus photon energy hn for Se clusters incorporated into a) LTA zeolites and b) FAU zeolites, together with that for bulk a-Se; a is the absorption coefficient in each zeolite. We have found by Raman scattering measurements and reported that the structure of Se clusters is intriguingly affected by the geometrical restriction in the zeolites [9,10]. Se clusters in 3A(K + ) have a helical chain structure or chain-like segment (i.e.…”