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New x‐ray intensity data from synthetic beryllium oxide crystals have verified the distorted wurtzite‐type structure previously reported by Jeffrey, Parry, and Mozzi. The oxygen z parameter obtained from the refinement is compared to 0. 375 for the undistorted structure. The resulting structure has a bond distance of parallel to the c‐axis and three distances of completing the tetrahedral coordination. The difference of 0. 014Aå appears statistically significant and indicates that the long bond has slightly more ionic character than the other three. Measurement of the signs of the piezoelectric and pyroelectric charge and the shape and rate of etch pit formation were correlated with the internal crystal structure to identify the crystallographic polarity. On crystals showing a hemimorphic habit, consisting principally of a hemipyramid, a prism and a dominant pedion, the dominant pedion has been shown to be terminated by oxygen atoms. In oxidizing etching media the surfaces are much more reactive than the 00. 1 surfaces. The differences in surface reactivity are consistent with a modified version of the Warekois‐Gatos hybrid orbital bonding model for and compounds. A discussion is presented relating the crystalline structure of beryllium oxide to its mechanical properties and mechanism of crystal growth.
Smith et al. (Wed,) studied this question.