Abstract
The relations between the vaporized amounts, vaporization behavior and spectral line intensity of gadolinium in graphite powder, and d. c. are discharge conditions have been examined with graphite electrodes.<BE>Standard samples were prepared with highly purified graphite powder, 1000 ppm of gadolinium as gadolinium oxide and various concentration of lithium fluoride as a spectrographic buffer substance. A d. c. arc technique was used for exciting the element, and the neutron activation analysis technique was used for measuring the concentration of gadolinium in graphite powder after arc discharge.
It was clarified that the vaporized amounts and vaporization behavior depended mostly on the electrode temperature. As an arc current increased, the vaporized amounts increased and the temperature. of anode was raised. Under the experimental conditions including d. c. 9.9 A-12.5 V, exposure time 60 sec, electrode gap 3 mm, and 2.0% of lithium fluoride in argon atmosphere, the vaporized amounts from mg sample were 3×10-7 g at anode crater and 2×10-7 g at cathode crater.
The emission line intensity of gadolinium depended on the vaporized amounts of gadolinium in argon. atmosphere. Under the experimental conditions including d. c.9.810A-12.012.5V, exposure time 60 sec, electrode gap 3 mm, and concentration of lithium fluoride from 0.5 to 10% the observed temperature range of the arc column was 28003600°K, and its correlation with the concentration of lithium fluoride was not linear. The arc column temperature was calculated by the equation ; log (Iλ/Ag) =-5040E/ T+C.
