Takayuki Nishi1, Toshio Oishi2 and Katsutoshi Ono2
1Graduate Student, Kyoto University, Kyoto
Trace amounts of oxygen around 1 mass ppm in pure copper were determined by an inert gas fusion infrared absorption method.
In this study, the following pretreatments for the graphite crucibles and the copper samples were introduced in the analysis of trace amounts of oxygen.
During the oxygen analysis, some residual gases were cared to come out from the crucible, which was used for the oxygen extraction in the impulse furnace, even after purging in that furnace. To decrease these gases, the graphite crucibles were degassed beforehand for 7.2 ks in a vacuum furnace at the pressure of 10-2 Pa and the temperature of 2000 K. The variation in the blank values was decreased by that operation, and the detection limit evaluated from the blank values was 0.3 μg/g.
Furthermore, the excess oxygen on the surface of the copper sample was also removed as much as possible. Before the copper sample was dropped into the graphite crucible for the extraction furnace, the surface of it was reduced under a stream of 5%H2-Ar mixing gas at 673 K for 600 s. Secondary ion mass spectrometry (SIMS) showed that hydrogen reduction treatment did not effect the oxygen concentration in the bulk.
As a result of those pretreatments, the analytical values of oxygen in copper and their standard deviations were lower than those without them.
The pretreatments mentioned above were, therefore, found to be effective for the analysis of the trace amounts of oxygen in copper.
copper, trace oxygen analysis, inert gas fusion infrared absorption method, secondary ion mass spectrometry
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