In:
Journal of Vacuum Science & Technology B, American Vacuum Society, Vol. 40, No. 5 ( 2022-09-01)
Abstract:
An alkali metal dispenser is the core device for vacuum evaporation in producing multialkali photocathodes. However, the reaction kinetic of alkali metal chromate being reduced by a Zr-Al alloy, which is the most commonly used alkali metal dispenser, has not been reported. In this work, we made composite particles of Zr-Al 16 wt. % powders with Na2CrO4 by a method of liquid precipitation. Through thermal analysis of its reaction, we found that the difference of a Zr-Al particle size would affect the reaction starting temperature but would not make a significant difference on the apparent activation energy. Through the comparison method by Sharp, we found that the 3D Avrami–Erofeev equation fits for this reaction and established a reaction degree-temperature function, and the reaction kinetic was further verified by a vacuum evaporation experiment. Through an in situ XRD measurement, the chemical change during an Na dispenser’s working process is found to be Na2CrO4 → Na2CrO4, Na2CrO3, and Cr2O3 coexist → NaCrO2. This work may serve as a reference for the design of alkali metal dispensers and help to improve the control precision for an evaporation process.
Type of Medium:
Online Resource
ISSN:
2166-2746
,
2166-2754
Language:
English
Publisher:
American Vacuum Society
Publication Date:
2022
detail.hit.zdb_id:
3117331-7
detail.hit.zdb_id:
1475429-0
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