Electron microprobe analysis was used to measure the distribution profile of nickel ion in and on the spinel layer during the spinel formation reaction from nickel oxide and alumina single crystals in the temperature range from 1,260^o to 1,470 ℃. The volume and surface diffusion coefficients of nickel ion（Dv, Ds） obtained are:
Dv = 8.54×10^-4 exp（-(48.6±5.8Kcal/mol / RT）) ㎠/sec,
Ds = 2.7×10^-1 exp（-(20.5±1.2Kcal/mol / RT）) ㎠/sec,
A confits model was proposed for measurement of surface diffusion coefficient under free sintering of powder and the application was carried out for free sintering data of zinc oxide.