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Old Aug 8th 2019, 06:43 AM   #1
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Davisson & Germer experiment

How does work function of tungsten decreases when coated with barium oxide??

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Old Aug 8th 2019, 07:22 AM   #2
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It doesn't. The barium oxide coating just has a lower work function, so the coating acts as the main electron emitter. Presumably electrons conduct from the tungsten to the barium oxide layer and are then liberated by absorbed radiation via the photoelectric effect.
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Old Aug 8th 2019, 08:52 AM   #3
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Then why they used Tungsten along with barium oxide? They could have used only barium oxide coated on any insulator!!??

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Old Aug 8th 2019, 10:43 AM   #4
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I can only guess that there were certain practical and or mechanical advantages to using Tungsten.
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Old Aug 8th 2019, 05:53 PM   #5
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Originally Posted by Sanketh View Post
Then why they used Tungsten along with barium oxide? They could have used only barium oxide coated on any insulator!!??

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Good question... I think my previous answer was incorrect.

According to Mishra & Garner (2004; I can't access it unfortunately, but the abstract speaks for itself...), it turns out that the total combined work function with tungsten + barium oxide is lower than both of the constituents separately because the chemical reaction between the two yields thermionic electrons.

Link to the paper: https://aip.scitation.org/doi/pdf/10...6451?class=pdf
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