Photochemically induced deposition of protective alumina coatings onto UV emitting phosphors for Xe excimer discharge lamps

Journal Article · Mon Aug 15 00:00:00 EDT 2016 · Materials Research Bulletin

DOI:https://doi.org/10.1016/J.MATERRESBULL.2016.04.008· OSTI ID:22581601

Broxtermann, Mike; Jüstel, Thomas

Highlights: • A UV-reactor for the pH induced precipitation of inorganic material is described. • The photolysis of Azide (N{sub 3}{sup −}) leads to a steady pH increase used for precipitation. • A UV induced Al(OH){sub 3} precipitation is used to craft Al{sub 2}O{sub 3} coatings onto YPO{sub 4}:Bi. • The influence of Al{sub 2}O{sub 3} coated onto YPO{sub 4}:Bi with different thicknesses is discussed. • SEM, VUV-spectroscopy and ESA measurements were performed on Al{sub 2}O{sub 3} coated samples. - Abstract: This work concerns the particle coating of the UV-C emitting phosphor YPO{sub 4}:Bi, targeting a stability enhancement of the phosphor material for Xe excimer lamp operation. To this end, the material is coated by the wide band gap material Al{sub 2}O{sub 3}. In order to obtain a thin and homogeneous coating layer, a novel process based on the photochemical cleavage of NaN{sub 3} in water was developed. This results in a slow and continuous enhancement of the pH value due to ongoing NaOH formation, which results in the precipitation of Al(OH){sub 3} from an Al{sub 2}(SO{sub 4}){sub 3} {sub ×} 18H{sub 2}O solution. It turned out that the obtained particle coatings are of much better quality, i.e. homogeneity, compared to coatings made from a wet-chemical homogeneous precipitation process. The morphology and electrochemical properties of Al{sub 2}O{sub 3} coated YPO{sub 4}:Bi are discussed on the basis of optical spectroscopy, ESA measurements, and SEM/EDX investigations.

• OSTI ID: 22581601
• Journal Information: Materials Research Bulletin, Vol. 80; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION SPECTROSCOPY
ALUMINIUM HYDROXIDES
ALUMINIUM OXIDES
ALUMINIUM SULFATES
AZIDES
COATINGS
ELECTROCHEMISTRY
FAR ULTRAVIOLET RADIATION
MORPHOLOGY
OPTICAL PROPERTIES
PH VALUE
PHOSPHORS
PHOTOCHEMISTRY
PHOTOLYSIS
PRECIPITATION
SCANNING ELECTRON MICROSCOPY
SODIUM HYDROXIDES
YTTRIUM PHOSPHATES
YTTRIUM SULFATES