We　present　a　comprehensive　study　on　the　phase,　emission　performance,　surface　composition,　chemical　states　and　evaporation　properties　of　a　75　at.%　Re-25　at.%　W　(75Re)　mixed　matrix　impregnated　cathode　by　several　modern　analyzers,　including　XRD,　electron　emission　test　device,　in　situ　AES,　XPS　and　Quartz　Crystal　Oscillation　Instrument　(QCOI).　On　the　basis　of　experimental　results,　the　adsorption　energy　and　charge　transfer　of　the　Ba-O　dipole　adsorbed　on　cathode　surface　was　investigated　by　the　first-principles　density　functional　theory　calculations.　The　in　situ　AES　analyses　indicate　that　the　atomic　ratio　of　Ba:O　of　the　active　emission　layer　on　the　cathode　surface　converged　to　3:2　for　a　conventional　Ba-W　cathode　and　to　about　3:　1　for　the　75Re　cathode.　Due　to　the　larger　adsorption　energy　of　Ba　and　Ba-O　on　75Re　cathode　surface,　the　total　evaporation　rate　of　Ba　and　BaO　in　the　75Re　cathode　is　much　lower　than　that　for　the　Ba-W　cathode,　which　is　agreed　favorably　with　the　experimental　evaporation　data.　Our　characterizations　and　calculations　suggest　that　rhenium　in　the　matrix　of　impregnated　cathodes　improves　the　stability　of　Ba-O　dipole　on　the　cathode　surface　and　enhances　the　emission　capability　substantially.　(C)　2017　Elsevier　B.V.　All　rights　reserved.