희토류 이온이 첨가된 인산염계 형광체의 분광학 특성

Abstract

Rare-earth (Eu3+, Tb3+) ions doped alkaline earth yttrium phosphate Ba3Y(PO4)3, Sr3Y(PO4)3, Ba3(1-x)Sr3xY(PO4)3 and Ca9Y(PO4)7 phosphors were synthesized by the high temperature solid-state reaction method. The formation single phases were confirmed by X-ray powder diffraction analysis. The luminescence properties of samples are investigated by optical and laser-excitation spectroscopy based on the analysis of the emission, excitation and time-resolved spectra. The luminescence intensity of Eu3+ ions in Ba3Y(PO4)3 and Sr3Y(PO4)3 increases by increasing concentration up to 90 mol%. The substitution of Sr2+ ions for Ba2+ ions in Ba3(1-x)Sr3xEu(PO4)3 gives rise to slight change in spectral feature, but the intensity is stronger for higher concentration of Ba2+ ions. In the excitation and emission spectra of the Tb3+ -doped Ba3Y(PO4)3 and Sr3Y(PO4)3 phosphors the relative intensity between the 5D3 → 7FJ (J = 6, 5, 4, 3, 2) transition and 5D4 → 7FJ (J = 6, 5, 4, 3) transition changes by changing Tb3+ concentration. The changes in relative intensity between the 5D3 → 7FJ transition and the 5D4 → 7FJ transition are ascribed to the cross relaxation between Tb3+ ions. No decrease in intensity with Tb3+ ions concentration up to 100 mol% is observed for Ba3Y(PO4)3:Tb3+ and Sr3Y(PO4)3:Tb3+. The Eu3+ ions doped in Ca9Y(PO4)7 lattice show similar behavior in luminescence intensity as a function of Eu3+ ions concentration to those of Ba3Y(PO4)3:Eu3+ and Sr3Y(PO4)3:Eu3+. The energy transfer, cross relaxation, energy diffusion and thermal quenching are discussed in these systems.