Investigation of Sintering Temperature Effect on Scandate Cathode Pore Structure and Mathematical Expression

In this study, changes in the surface pore structure depending on the sintering temperature of the cathodes used in vacuum electronic devices were investigated. Ammonium meta tungstate (AMT) [(NH4)6(H2W12O40)4H2O](99.9% w/w), Sc(NO3)3(99.99% w/w), and 4:1:1 barium calcium aluminate (BCA) were purchased and used without further purification. Tungsten powders were doped with scandium nitrate and BCA. After synthesizing the powder, consecutive material characterization analyses were conducted. The sintering processes were carried out at different temperatures in a hydrogen atmosphere and the pore structure was studied in detail by SEM and EDS analyses. The experimental data were analysed with a mathematical modelling to investigate the relationship between sintering temperature and pore diameters. Two pieces of function were utilized to describe the pore size and sintering temperature relation. The effect of sintering temperature on the pore structures of the cathode surface has been studied and the importance of pore dimensions on cathode performance and life has been emphasized. Therefore, this mathematical modelling offers a promising prediction technique by saving time and cost.