Anisotropy in the Atomic Vibrations of Zinc Crystals. II. Diffuse Scattering of X-Rays from Single Crystals

Abstract

The general radiation from a tungsten tube was used together with Jauncey and Claus' method of integration over all wave-lengths. Because of the high absorption coefficient of zinc it was necessary to scatter the x-rays from the front surface of the zinc crystals. Correction for the presence of fluorescent rays was made. A number of zinc crystals were grown. The control of the direction of the major and minor axes with respect to the surface of the crystal is described. Two types of experiment were made: (1) the variation of $S$ with $\psi$, the orientation angle, for a fixed value of $\phi$, the scattering angle; and (2) the variation of $S$ with $\phi$ for two fixed values of $\psi$, one near 90° and the other near 0°. (1) gave remarkable confirmation of the correctness of the form of Zener's formula for the Debye-Waller $M$ for hexagonal crystals, while (2) confirmed in a general way our values as obtained in (1) for $a$ and $b$ in Zener's formula. We find a much higher anisotropy, $a-b=1.66\mathrm{}$, than that suggested by Brindley, $a-b=0.785\mathrm{}$.