Formation of $\text{Ba}_{3}\text{Sc}_{2}\text{WO}_{9}$ on the $\text{Ba}_{2}\text{ScAlO}_{5}$ Therminoic Cathode Surface

A large number of surface analysis techniques yield the distribution and proportions of the elements on the surface. Unfortunately, little has been reported about the compounds and phase structures of the surface layers. It has been found some compounds containing Ba and Sc including
$\text{Ba}3\text{Sc}_{2}\text{WO}_{9}$
display low work function. While these compounds are rarely reported for practical operation cathodes. This work aims to identify the formation of
$\text{Ba}3\text{Sc}_{2}\text{WO}_{9}$
on the
$\text{Ba}2\text{ScAlO}_{5}$
cathode surface by controlling the evacuating process. Our results reveal that residual oxygen is crucial for the formation of the compound
$\text{Ba}3\mathrm{S}_{\mathrm{C}2}\text{WO}_{9}$
. Finally, a routine process for the generation of a
$\text{Ba}3\text{Sc}_{2}\text{WO}_{9}$
layer is provided.