Cathode Coatings for Electron Emission: Investigating Materials and Techniques

[Aleena753]

Homework Statement

What 3 materials is the cathode coated with, from which the electron originate?

Homework Equations

None

The Attempt at a Solution

From what I managed to find, I think some may be nickel and barium but I'm not sure.

 

[Simon Bridge]

Since this is homework, you have to find out for yourself.
How would you go about this?

It's also very difficult to work out what sort of answer is expected.
i.e. most common cathodes have an oxide coating.
http://link.springer.com/article/10.1007/s10854-006-0020-5