Low-work-function surfaces with ϕ as low as 2.0 eV produced by alkaline earth element carbonate decomposition Original Research Article

In order to characterize the surfaces produced by alkaline earth metal carbonate decomposition, which has been known as high electron emission properties, studies have been made in terms of thermionic emission properties (electronic work function, ϕ), comparison with the well-established LaB6 surface, thermal stability and negative surface ionization yields. Mass spectrometric measurements of negative ion current from these surfaces were made for iodine as a test sample. The conclusion is that (1) the work function of the surface with deposited materials from BaCO3:SrCO3:CaCO3 was as low as 2.0 eV and the value is among the lowest ever reported except for cesium-oxygen surfaces, (2) air environment accelerates the decay of thermionic emission; ϕ was increased by the chemisorption and (3) high I− ion currents can be obtained with tricarbonate decomposition products on the Re ribbon filament.