A dilatometer of exceptionally high sensitivity has been developed and used to measure the thermal expansion of polycrystalline samples of copper, silver and gold and of a single crystal of copper in the range 4.2 to 15°K. The results obtained for copper were in excellent agreement with the work of other researchers and the error estimates were sufficiently small to show that the theoretical calculations of Collins are not supported by measurements on a polycrystalline specimen of copper. Below 15°K the data points were well represented by the equation: 1010a=1.54+/-0.04 T+0.275+/-0.0027T 3 The results obtained for a single crystal of copper were significantly different from those obtained for a polycrystalline sample yet they are also in disagreement with the theoretical value. Below 15°K the data fitted the equation: 1010a=3.13+/-0.05 T+0.255+/-0.003T 3 Values of Yo (the low temperature limiting value of the Gruneisen parameter) for silver and gold were measured to be 2.04 +/- 0.06 and 2.91 +/- 0.02 respectively. The agreement with the theoretical values 2.22 and 2.92 is quite good. Below 6°K the thermal expansion of silver and gold was found to be anomalous as it was no longer proportional to the specific heat of these metals. In order to obtain high accuracy in the values of thermal expansion it was necessary to measure temperature to about 0.01°K. For this purpose a method was developed to obtain an interpolation of the resistance versus temperature function in the range 4.2 to 10°K. This capability permitted a theoretical study of the electrical resistivity of pure platinum which indicated that d-band electrons contribute significantly to the conductivity at low temperatures. In the hope of obtaining better measurements of temperature indium resistance thermometers were designed and constructed. Their reproducibilities were measured and were found to exceed previously reported values for indium resistance thermometers.
| Identifer | oai:union.ndltd.org:uottawa.ca/oai:ruor.uottawa.ca:10393/11093 |
| Date | January 1967 |
| Creators | Kos, Joseph F. |
| Publisher | University of Ottawa (Canada) |
| Source Sets | Université d’Ottawa |
| Detected Language | English |
| Type | Thesis |
| Format | 134 p. |
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