SC2O3-W　matrix　cathodes　have　been　prepared　by　using　a　liquid-liquid　doping　method　combined　with　high-temperature　sintering.　The　microstructure　and　physical　behavior　of　active　substances　of　scandiadoped　tungsten　matrix　and　impregnated　cathode　has　been　studied　by　SEM　and　AES　methods.　The　results　show　that　the　matrix　has　a　homogeneous　structure　composed　of　W　grains　with　spherical　shape　and　superfine　Sc2O3　particles　dispersed　uniformly　over　and　among　W　grains.　After　impregnation,　this　Sc-type　impregnated　cathode　has　high　emission　capability.　Space-charge-limited　current　density　could　reach　52　A/cm(2)　at　850　degrees　C-b.　The　high　emission　results　from　a　Ba-Sc-O　active　layer　with　a　thickness　of　about　80　nm,　which　is　formed　at　the　cathode　surface　during　the　activation　period.　Both　the　decrease　of　the　thickness　of　active　surface　layer　and　the　decrease　of　the　content　of　Sc　at　the　surface　could　lead　to　the　degradation　of　current　density　during　operation.　(c)　2008　Elsevier　Ltd.　All　rights　reserved.