Investigation of evolved layer structure of Ba-containing emission materials

Ildikó Beck, K. Josepovits, János Sneider

Research output: Article

Abstract

The emission material in High Intensity Discharge (HID) lamps plays a significant role in lowering the electrode work function and thus the lamps' operating temperature. Ba-containing rare earth- and alkali earth tungstate materials are commonly used as cathode thermionic emission materials because of the production of high intensity discharge. The goal of this present work is to model a cathode tip surface evolved during sintering and to compare the physical and chemical properties of emission materials currently used in the industry. In order to achieve this goal, we investigated and compared the layer structure of Ba-Ca- and Ba-Y-containing emission materials evolved on polycrystalline tungsten foils. Simultaneously, the tendency of the work function was also monitored as a function of Ba/BaO layer thickness. The Ba coverage of cathode is one of the most important factors during the lifetime of HID lamps. The initial Ba diffusion was also examined. We also proposed a layer model, valuable for the structures occurring during the operation of lamps. The chemical composition of the flat samples was analysed by X-ray Photoelectron Spectroscopy (XPS) and the electron emission properties by Work Function Spectroscopy (WFS).

Original languageEnglish
Pages (from-to)9-12
Number of pages4
JournalPeriodica Polytechnica: Chemical Engineering
Volume51
Issue number2
DOIs
Publication statusPublished - 2007

Fingerprint

Discharge lamps
Cathodes
Electric lamps
Thermionic emission
Tungsten
Electron emission
Alkalies
Chemical properties
Metal foil
Rare earths
Sintering
X ray photoelectron spectroscopy
Physical properties
Earth (planet)
Spectroscopy
Electrodes
Chemical analysis
Industry
Temperature
tungstate

ASJC Scopus subject areas

  • Chemical Engineering(all)

Cite this

Investigation of evolved layer structure of Ba-containing emission materials. / Beck, Ildikó; Josepovits, K.; Sneider, János.

In: Periodica Polytechnica: Chemical Engineering, Vol. 51, No. 2, 2007, p. 9-12.

Research output: Article

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