A study on the chromaticity shifts of blue phosphor for color plasma displays

Abstract

Abstract— The dependency of the chromaticity shifts on the concentration of Eu2+ doped in BaMgAl10O17 (BAM) was investigated under heat‐treatment and vacuum ultraviolet (VUV) irradiation. The Eu2+ ions in BAM show an asymmetrical broad emission band with a maximum at ∼452 nm under excitation of VUV light at room temperature, showing that multiple crystalline cationic sites exist in the host. It was found that the chromaticity shifts greatly decrease with increasing heat‐treatment temperature. Regardless of the Eu2+ concentration, the chromaticity shifts caused by heat‐treatment are greater than that caused by VUV irradiation. Compared with conventional BAM, a solid solution of BAM with barium aluminate as a powder and film was also studied, and very few chromacity shifts were observed. It is suggested that the distribution of Eu2+ ions in different sites in a BAM lattice results in different chromaticity coordinates. By increasing the Eu2+ concentration in BAM, or under heat‐treatment and VUV irradiation, the emission band shifts towards longer wavelengths.

Characterization of host-lattice emission and energy transfer in BaMgAl10O17:Eu2+

“…A new Eu 2+ emission peak appears at about 500 nm, along with an even broader tail that extends beyond 600 nm. The peak at B500 nm has been reported before for VUV-damaged BAM doped with 10% Eu [18]. The new features in the emission spectra may come either from newly formed electronic defect centers in the host lattice, or from new Eu 2+ centers.…”

Photoluminescence degradation and color shift studies of annealed BaMgAl10O17:Eu2+ phosphor

“…2 present an asymmetrical broad band with a maximum around 450 nm. This is due to the multiple crystalline sites for Eu 2+ to occupy [8]. Therefore, the distribution of Eu 2+ in different sites will result in different emission spectral features, such as peak position and full-width at halfmaximum (FWHM), which leading to different chromaticity coordinates.…”

“…The oxidation of Eu 2+ has been well accepted as the thermal degradation mechanism [3][4][5], but recent studies suggested contrary interpretations such as an altered local environment of Eu 2+ [6] or the intercalation of water in the conduction layer [7]. In addition, the annealing-induced color shift of BAM has been reported [4,8], but its reason is still not explained. Therefore, the thermal degradation mechanism of BAM still remains somewhat mysterious and needs more efforts to study.…”

Effects of Si4+ and B3+ doping on the photoluminescence of BaMgAl10O17:Eu2+ phosphor under UV and VUV excitation

“…This asymmetry is due to the multiple crystalline sites for Eu 2+ to occupy in BaMgAl 10 O 17 host [16]. According to Refs.…”