Toshinori Isobe

First-principles study of blue silicate phosphors

First-principles calculations were performed to investigate the optical property of blue silicate phosphor, CMS:Eu. The optical absorption property is discussed based on electronic band structure and density of states. Our calculation results indicate that hybridization of the wavefunction plays an important role for nonradiative migration of electrons and holes. The calculated optical absorption spectrum could reproduce the optical features of the experimental excitation spectrum. It is also demonstrated that a practical approach using computational materials screening is effective in phosphor materials development.

Density functional study for optical properties of blue silicate phosphor: BaCa2MgSi2O8

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.