An attempt to measure the diffusion of aluminum into natural aluminum oxide

The goal of this research was to investigate the diffusion of aluminum ions in natural aluminum oxide grown under atmospheric conditions. The basis for the approach employed here had been developed earlier by J. H. Christian and H. L.Taylor. However, these authors studied the diffusion of aluminum ions in an oxide grown in a pure oxy­gen atmosphere. They utilized a glass slide upon which aluminum metal was deposited in vacuo (10-11 Torr). Oxide was then allowed to grow on this metal by back-filling the vacuum with pure oxygen to a pressure of 40 to 50 m Torr while infrared lamps heated the aluminum metal substrate to 550° K. After again pumping to a low pressure, and with the substrate at room temperature, a second evaporation of aluminum was made which formed the other electrode. Connection was made to these electrodes by metal spring contacts . They determined the diffusion current by measuring the potential drop across a 100 ohm resistor in series with the electrodes