Stabilization of Eu³⁺ under a reductive atmosphere by the Al³⁺ co-doping of Sr₂SiO₄:Eu²⁺/Eu³⁺

Abstract

The incorporation of aluminum ions into the Sr2SiO4:Eu causes the stabilization of the Eu3+ ions under reductive atmosphere and concentration ratio of europium in both oxidation states ([Eu3+]/[Eu2+]) can be controlled by changing the Al3+ content.

Influence of Al3+co-doping on the spectral properties of europium doped Ca9Y(PO4)7

“…The reduction of Eu 3+ occurs when the negative compensator of Eu Ca is locally neutralized. [12][13][14][15] The neutralization process can be attributed to the physical elimination of the compensator from the surroundings of Eu 3+ or to the emergence of another positively charged defect in the surroundings of the compensator. When the concentration of aluminum increases, the compensation of Eu 3+ via the Al 00 P becomes more probable, thus, naturally created compensators of europium, e.g.…”

“…One way is to introduce into the phosphor matrix the ions in oxidation state which is different from the oxidation state of the ions of matrix anionic sublattice, e.g. introducing Al 3+ ions in the place of Si 4+ ions in silicates 12 or Si 4+ ions in the place of P 5+ ions in phosphates. 13 Another way is to change the stoichiometric ratio of ions in the matrix, e.g.…”

The influence of charge compensation defects on the spectroscopic properties of europium doped Ca9Y(PO4)7

“…Generally, during a reduction process, the gaseous hydrogen, considered as a reducing agent, creates additional oxygen vacancies ðV cc O Þ on the surface of the material particles. 30 Because the charge compensation in the materials has a local character (short distance compensation), the reduction of Eu 3+ to Eu 2+ will occur, when the compensation defect of Eu c Ca is locally eliminated. The V cc O created on the surface during the reduction cannot cause the elimination of Ca 0 Y from the surroundings of Eu 3+ and for the reduction of the europium ion, the created oxygen vacancy has to be moved from the surface to the vicinity of the Eu 3+ and Ca 0 Y .…”

“…From the energy difference, it stems that the migration of calcium vacancies to the surface is much more probable than the migration of oxygen vacancies to the bulk crystal to compensate each other. 30 Fig. 13 shows the scheme of the described situation.…”

Synthesis and luminescence properties of single‐component Ca5(PO4)3F:Dy3+, Eu3+ white‐emitting phosphors

“…Therefore, it is necessary to investigate a single‐component white‐emitting phosphor with near‐ultraviolet (n‐UV) excitation. Until now, many single‐component white‐emitting phosphors have been reported, such as Eu 2+ –Mn 2+ , Mn 2+ –Tb 3+ , Ce 3+ –Tb 3+ , Eu 2+ –Eu 3+ co‐doped silicates, phosphates, etc . In addition to using such doped systems, white light can also be acquired by combining the two intense emission bands in the blue (~480 nm) and yellow regions (~580 nm) of Dy 3+ ions .…”