Anisotropic Thermal Expansion of Single Crystals of Thallium, Yttrium, Beryllium, and Zinc at Low Temperatures

Abstract

The anisotropic thermal expansion of the hexagonal elements, thallium, yttrium, beryllium, and zinc, has been measured. The temperature range for the thallium, yttrium, and zinc measurements was 4.2−273.2°K, while for beryllium the range was 77−273.2°K. Dimensional changes were detected by an interferometric technique, and the movement of the interference fringes was detected with a photomultiplier tube. From the measured values of ΔL/L0 the coefficients of thermal expansion and the c/a ratios of the metals were calculated as a function of temperature. A review of previous measurements of the thermal expansion of these metals is also included.