Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 31 January 1964:
Vol. 143. no. 3605, pp. 467 - 469
DOI: 10.1126/science.143.3605.467
Prev | Table of Contents | Next

Articles

Negative Temperature Coefficient of Resistance in Bismuth I

P. C. Souers 1 and G. Jura 1

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

Measurements of the electrical resistance have been made on bismuth 1 between 15 and 35 kilobars at temperatures between 77.4° and 120°K. Above about 150°K, the temperature coefficient of resistance is positive, as in a metal; below 150°K, the coefficient becomes negative, as is characteristic of semiconductors. On the basis that bismuth is a semiconductor, the energy gap, calculated by the exponential resistance formula, is 0.006 ev at 15 kb with a steady rise to 0.018 ev at 35 kb. At higher pressures, bismuth I is transformed into a metallic modification with the normal temperature dependence of the resistance. The energy gap in bismuth I is not visible at room temperature because thermal excitation populates the conduction band and metallic behavior is the result. From available evidence the observed behavior is due to an energy gap rather than to a decrease in carrier mobility.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
The Pressure Variable in Materials Research.
D. B. McWhan (1972)
Science 176, 751-758
   PDF »
High Pressure: Effect on Dysprosium.
P. C. Souers and G. Jura (1964)
Science 145, 575-577
   Abstract »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)