Some requirements for electronic properties of a material for MHD: Thermal emission of electrons

There have been significant advances in MHD (magnetohydrodynamics) conversion recently. Hower, the lifetime of electrodes remains too short due to degradation derived from several mechanisms. Electrical degradation is a consequence of an ionic conductivity contribution and of inefficient thermal emission of electrons. The last factor is analyzed for oxides. Point defects are important to understand the effect of the gaseous environment and influence mainly the preexponential term in electron emission expressions. A correlation between the electron affinity and the band gap E_g may help to determine a rough value of . Oxides with low electron affinity and appropriate doping appear attractive for further research.