Doped strontium vanadate: Computational design of a stable, low work function material

Abstract

In this work, we have built upon our previous discovery of strontium vanadate (SrVO3) as a new, low work function electron emission material. Using Density Functional Theory methods, we have alloyed pure SrVO3 with 46 different elements and predicted work function changes from pure SrVO3 using the oxygen 2p energy states as a bulk electronic structure descriptor. We have shown that bulk doping of SrVO3 is not expected to result in a lowered work function. Instead, it is purely by enhancement of surface dipoles that Ba, when residing directly at the emitting surface, creates an ultra-low predicted work function of just 1.07 eV. In addition, thermodynamic phase stability calculations under realistic cathode operating conditions demonstrate that small additions of Cr, Mn, Fe, and Mo on the SrVO3 B-site may further improve the stability of SrVO3 while maintaining its metallic conductivity.