Linear thermal expansion of SrTiO3

The linear thermal expansion of SrTiO3 in the temperature range 10 to 150 K is measured with a relative accuracy of 5 x 10-7 by using a three-terminal capacitance dilatometer. The dilation ΔL/L of a single-domain crystal is converted to the ratio of the pseudo-cubic cell constants a(T)/a(T/sub a/) by the equation a(T)/a(T/sub a/) = [1 + (ΔL/L)/sub T/]/[1 + (ΔL/L)/sub T//sub a/], where L is the specimen length, T/sub a/ is the cubic-to-tetragonal transition temperature and T <= T/sub a/. The present a(T)/a(T/sub a/) curve shows a coincidence with the temperature dependence of cos phi between 40 and 108 K, and reveals a clear difference with it below 40 K, where phi is the rotation angle of the TiO6 octahedra around the [001] axis. The temperature at which the dilation shows a minimum, 37.5 K, is very close to the transition point T/sub c/ = (32 +- 5) K predicted by Cowley. (author)