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2. P. Chaudhari, J. J. Cuomo and R. J. Gambino, IBM Dev. 11, 66 (1973).
3. A. E. Clark, Appl. Phys. Lett., 23, 642 (1973).APPLAB0003-6951
4. J. J. Croat, to be published.
5. High purity Pr was obtained frora the Metallurgy and Ceramics Dept., Ames Laboratory (DOE), Ames, Iowa.