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Science 3 May 1963:
Vol. 140. no. 3566, pp. 481 - 483
DOI: 10.1126/science.140.3566.481
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Articles

Semiconducting Region of Ytterbium

P. C. Souers 1 and G. Jura 1

1 Department of Chemistry and Inorganic Materials Research Division, Lawrence Radiation Laboratory, University of California, Berkeley 4

The resistivity of elemental ytterbium at room temperature rises, by a factor of 11, to a maximum at a pressure of 40 kilobars; a further increase in pressure causes a polymorphic transition; the new phase has a resistivity 80 percent of that of the metal at 1 atmosphere. In the temperature-pressure diagram, the phase boundary has a negative slope. The phase boundary, determined from -190° to 360°C, is a straight line that may be extrapolated nearly to the known agr-beta transition at 1 atmosphere. Between the transition pressure and 20 kbar, the lowest pressure at which the measurements were made, ytterbium behaved as a semiconductor. The temperature coefficient of resistance is negative; at constant pressure, the resistivity shows the exponential temperature dependence characteristic of a semiconductor. The parameter in the expontial would correspond to an energy gap 0.015 ev at 20 kbar, an increase with pressure to a maximum of 0.080 ev at 37 kbar, and then a decrease to 0.05 ev at 45 kbar.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
High-Pressure B-Type Polymorphs of Some Rare-Earth Sesquioxides.
H. R. Hoekstra and K. A. Gingerich (1964)
Science 146, 1163-1164
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High Pressure: Effect on Dysprosium.
P. C. Souers and G. Jura (1964)
Science 145, 575-577
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Negative Temperature Coefficient of Resistance in Bismuth I.
P. C. Souers and G. Jura (1964)
Science 143, 467-469
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