Abstracts of Technical Articles by Bell System Authors 



Investigation of Oxidation of Copper by Use of Radioactive Cu Tracer} J. 

 Bardeen, W. H. Brattain, and W. Shockley. A very thin layer of radio- 

 active copper was electrolylically deposited on a copper blank. The surface 

 was then oxidized in air at 1000°C for 18 minutes, giving an oxide layer with 

 a thickness of 1.25 X 10"^ cm. After quenchirg, successive layers of the 

 oxide were removed chemically, and the copper activity in each layer was 

 measured. The observed self-diffusion of radioactive copper in the oxide 

 agrees quantitatively with a theory based on the following assumptions: (a) 

 The oxide grows by diffusion of vacant Cu+ sites from the outer surface of 

 the oxide inward to the metal, (b) The concentration of vacant sites as the 

 oxygen-oxide interface is independent of the oxide thickness, and drops 

 linearly from this constant value to zero at the metal boundary, (c) Ac- 

 companying the inward flow of vacant sites, there is a flow of positive elec- 

 tron holes such as to maintain electrical neutrality, (d) Self-diffusion of 

 copper ions takes place only by motion into vacant sites. The results give 

 a fairly direct confirmation of the theory of oxidation first suggested by 

 Wagner. 



A New Magnetic Material of High Permeability} (). L. Boothby and 

 R. M. BozoRTH. This paper describes the preparation, heat treatment, and 

 properties of supernialloy, a magnetic alloy of iron, nickel, and molybdenum. 

 In the form of 0.014 in. sheet it has an initial permeability of 50,000 to 

 150,000, a maximum permeability of 600,000 to 1,200,000, coercive force of 

 0.002 to 0.005 oersted, and a hysteresis loss of less than 5 ergs/cm^ /cycle at 

 B = 5000. Transformer cores made of insulated 0.001 in. tape, spirally 

 wound, have about the same initial permeability and a maximum permeabil- 

 ity of 200,000 to 400,000. The alloy has a Curie point of 400°C and appears 

 to have an order-disorder transformation temperature somewhat above 

 500°C. 



Magnetoresistance and Domain Theory of Iron-Xickel Alloys? R. M. 

 BozoRTH. Measurements of change of electrical resistivity with magneti- 

 zation and with tension are reported for iron-nickel alloys contai'ii-g 40 to 

 100 i)er cent nickel. When the magnetostriction is negative (81 to 100 per 



' Jour, oj Chemical Ptiysics, December 1946. 

 '^ Jour. Applied Physics, February 1947. 

 ' Phys. Rev., Dec. 1 and 15, 1946. 



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