음이온이 정렬된 M3AlO4F:Eu3+(M=Ca,Sr,Ba) 형광체의 분광학 특성 연구

Abstract

Luminescence properties of Eu3+ ions doped in Sr3-xMxAlO4F (M=Ca, Sr, and Ba) are investigated by optical and laser-excitation spectroscopy at 15 K and room temperature. Significant spectral line broadening of emission line due to the 7F0 → 5D0 transition of Eu3+ is observed in the M3AlO4F (M=Ca, Sr, Ba) lattices. The structural characteristics of Sr3AlO4F with two different layers compartmentalizing two Sr sites are responsible for the inhomogeneous line broadening in M3AlO4F (M=Ca, Sr, Ba). The selectively excited emission spectra of the 5D0 → 7FJ (J=1 and 2) transitions exhibit crystal field splittings with site-to-site variation. Substitution of Ca, Sr, and Ba ions by Sr ions in Sr2.5M0.5AlO4F gives rise to larger crystal field splittings in the sequence of smaller ionic radii Ca, Sr, and Ba. The decay times of the emission at 612 nm due to the 5D0 → 7F0 transition becomes shorter for higher energy side on the inhomogeneously broadened 7F0 → 5D0 emission line indicating that Eu3+ at higher energy side of the 5D0 state experiences stronger crystal field strength. The results are discussed in relation with crystal field parameters of B20 and B22 and crystal field strength of Nν (B2q ).