Fine-sized BaMgAl10O17:Eu2+ phosphor powders prepared by spray pyrolysis from the spray solution with BaF2 flux
Introduction
BaMgAl10O17:Eu2+(BAM:Eu) phosphor, which has plate-like structure in conventional preparation methods, is an important blue-emitting phosphor for plasma display panels (PDPs) and fluorescent lamps [1], [2], [3], [4], [5], [6], [7], [8], [9], [10]. The phosphor powders with fine size and regular morphology are required to obtain the good phosphor layer with low thickness for high definition PDPs. BAM:Eu phosphor powders with high photoluminescence intensities under ultraviolet and vacuum ultraviolet should be post-treated at high temperatures above 1500 °C under reducing atmosphere. Flux materials, such as AlF3 and BaF2, were applied in the solid-state reaction method to reduce the preparation temperature of the BAM:Eu phosphor powders.
Flux materials were also applied to the preparation of phosphor powders by spray pyrolysis. Flux materials dissolved to the spray solution were effective in improving the brightness of the phosphor powders by eliminating the surface defects of the powders [11], [12], [13]. In the previous paper, the AlF3 flux material insoluble in distilled water was applied in the preparation of blue-emitting BAM:Eu phosphor powders by the spray pyrolysis [14]. The precursor powders prepared by spray pyrolysis from the spray solution without flux material were reacted with AlF3 flux by solid-state reaction method. AlF3 flux improved the morphological and optical properties of the BAM:Eu phosphor powders.
In this study, fine-sized BAM:Eu phosphor powders with plate-like morphology were prepared by spray pyrolysis process from the spray solution with flux material. The effects of ratio of BaF2 and Ba(NO3)2 used as the source materials of Ba component on the morphological and optical properties of the BAM:Eu phosphor powders were investigated. BaF2 was used as the flux material as well as the source material of Ba component.
Section snippets
Experiment
The BAM:Eu precursor powders were prepared by ultrasonic spray pyrolysis from the spray solutions with BaF2 and Ba(NO3)2. The ultrasonic spray pyrolysis system has a droplet generator, a quartz reactor, and a powder collector. A 1.7 MHz ultrasonic spray generator with six resonators is used to generate large amount of droplets. The length and diameter of the quartz reactor are 1200 and 50 mm, respectively. The flow rate of the air used as the carrier gas was 30 L/min. The preparation temperature
Results and discussion
The effect of BaF2 flux on the optical properties of the BAM:Eu phosphor powders prepared by spray pyrolysis was investigated as the previous study. Small amount of BaF2 added to the spray solution with stoichiometric composition of BAM:Eu phosphor did not improve the optical characteristics of the phosphor powders. Therefore, in this study, the amount of Ba component dissolved to the spray solution was maintained to the stoichiometric composition of BAM:Eu phosphor. Fig. 1 shows the SEM images
Conclusions
The BAM:Eu phosphor powders were prepared by spray pyrolysis process from the spray solutions with the various ratios of BaF2 and Ba(NO3)2. BAM:Eu phosphor powders prepared from the spray solutions with appropriate BaF2 contents had regular morphologies, fine sizes and narrow size distributions. Addition of BaF2 improved the photoluminescence intensities of the BAM:Eu phosphor powders. The phosphor powders with the maximum photoluminescence intensity was obtained from the spray solution with
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2022, Journal of LuminescenceCitation Excerpt :Over the period of long history of these phosphors, a variety of methods aiming at simpler procedures have been employed. These include use of precursors which decompose and react at lower tempertures [42], decomposition of metal complex [43], citrate complex method [44], nano-coating method [45], sputtering [46], radio frequency sputtering [47], aerosol flame deposition [48], polymeric gel deflagration [49], Aerosol Pyrolysis [50], spray pyrolysis [51], flux-assisted spray pyrolysis [52], flame spray pyrolysis [53], atomic layer deposition (ALD) [54], Microwave synthesis [55], microwave irradiation technique [56], hydrothermal synthesis [57]. Ingenious tricks have been used for simplifying the synthesis.
A structural approach of the flux effect on blue phosphor BAM:Eu (BaMgAl<inf>10</inf>O<inf>17</inf>:Eu<sup>2+</sup>)
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Preparation of BaMgAl<inf>10</inf>O<inf>17</inf>:Eu<sup>2+</sup> phosphor with small particle size by co-precipitation method
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