Abstract
The apparatus enables the thermal diffusivity of a wide range of solids to be measured to an accuracy of +or-2% using the Angstrom method. It features a low-frequency sine-wave generator which produces stable sinusoidal temperature conditions at the heater, and a digital phase meter which measures phase directly in degrees with a resolution of 0.1 degrees . A low-noise amplifier and an active bandpass filter are used to improve the signal-to-noise ratio whenever conditions are such that the signals from thermocouples or probes are weak. Results are reported of the thermal conductivity of samples of single-crystal silicon and germanium in the temperature range 300-700K.