The Atomic Vibrations of a Zn-Cu Alloy

Measurements of x-ray reflection intensities at two temperatures have been made on the $21\overline{3}1$ and $10\overline{1}5$ lines from an alloy of copper and zinc. The idea is put forward that the atomic vibrations should be greatest along the $c$ axis of the crystal in case the axial ratio is greater than 1.633, least when the axial ratio is less than 1.633. The values obtained for the relative amplitudes of vibration along and perpendicular to the $c$ axis confirm this idea. The relative atomic structure factors are also found and show a surprising dependence on the angle which the normal to the reflecting plane makes with the $c$ axis.