INVESTIGATION OF THE INFLUENCE OF DEFECTS ON THE HEAT CONDUCTIVITY OF NON-METALLIC CRYSTALS, PARTICULARLY SUBSTITUTED ALUMINIUM OXIDE (A1203)
Abstract
An apparatus was designed in which heat conductivity can be measured over the temperature range 1 to 100 K. The specimen is mounted beneath a large gas thermometer bulb, the temperature of which can be controlled by balancing the heat influx from the surroundings, at liquid air or liquid H temperature, against the cooling effect of contact with H or He boiling off from a reservoir of liquid. An Au/Co vs Cu thermocouple was calibrated and an Au/Fe vs Ag/Au thermocouple will be examined. Super-conducting reversing switches, immersed in liquid He, are included in the thermocouple measuring circuits to eliminate all thermal emf's arising in the leads above 4 K. The apparatus will also measure specimens in a magnetic field up to 15,000 oe. Measurements were made on LiF with different Li-6/Li-7 proportions. In the liquid H range, the conductivity is much higher than that of any of the isotopically less pure specimens, and the value at 30 K agrees with the curve of conductivity vs composition. Measurements made on 2 paramagnetic rare earth double nitrates showed lower conductivities than a diamagnetic crystal. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 31, 1961
- Accession Number
- AD0268577
Entities
People
- Reena Berman
Organizations
- University of Oxford