A new thermal conductivity apparatus for small conducting specimens and measurements on niobium monoxide
Abstract
An apparatus for measuring the thermal conductivity and other transport properties of small conducting specimens was designed and constructed using the Kohlrausch-Callendar type method, where the heat source is the Joule heating of the specimen itself caused by passing an electric current through. The apparatus was used to measure the thermal conductivity, electrical resistivity, and the thermoelectric power of two NbO specimens in the temperature range of 100 to 650K. The Lorenz ratio showed a positive deviation from the Sommerfeld value for simple metals that was attributed to the energy band structure effect. The impact of the band structure effect in interpreting the temperature dependence of electrical resistivity was discussed. The results suggest that reservations should be made when the theory of normal metals is applied to conducting oxides and other compounds, because many of the nonmetal conductors are known to have complex energy band structures.
- Publication:
-
Ph.D. Thesis
- Pub Date:
- December 1979
- Bibcode:
- 1979PhDT........70H
- Keywords:
-
- Conductivity Meters;
- Electrical Resistivity;
- Niobium Oxides;
- Thermal Conductivity;
- Thermoelectricity;
- Electric Conductors;
- Energy Bands;
- Ohmic Dissipation;
- Resistance Heating;
- Temperature Dependence;
- Thermal Conductors;
- Instrumentation and Photography