Japan Association for Chemical Innovation

A density functional calculation is performed to investigate optical properties of blue silicate phosphor, BaCa2MgSi2O8:Eu (BCMS:Eu). The optical absorption and emission processes are discussed based on electronic band structures and density of states. Our calculation indicates that hybridization of the wave function plays an important role for nonradiative migration of electrons and holes. Our results also explain adequately the luminescence feature of BCMS which exhibits two components of blue emission from Eu ion substituted for Ba and Ca site. In addition, it is shown that the structural relaxation around Eu ion does work effectively to describe appropriately the difference of crystal field strength between Ba and Ca sites in BCMS host.

Abstract Two-electron reduction of 4,4′-(1,3-propanediyl)bis(N-methylpyridinium) dibromide with sodium amalgam in degassed solvent affords the titled compound, which is characterized by means of NMR, mass, ESR, and UV-vis absorption spectroscopies. Under deoxygenated conditions, the dispiro compound is stable for a long time at room temperature, but undergoes a decomposition reaction at high temperatures above 200 °C to give several degradation products.