Stability of the Wurtzite Structure

An analysis of available data for 20 wurtzite compounds of the ${A}^{N}{B}^{8\ensuremath{-}N}$ type shows that the stability as compared with zinc blende is closely connected with deviations of the $\frac{c}{a}$ ratio from the ideal value of 1.633. A simple qualitative model is proposed to account for this feature. The variation in $\frac{c}{a}$ is then correlated with the charge parameter $\frac{\mathrm{ZC}}{\ensuremath{\hbar}{\ensuremath{\omega}}_{p}}$, where $Z$ is the (effective) valence, $C$ Phillips's electronegativity difference, and $\ensuremath{\hbar}{\ensuremath{\omega}}_{p}$ the plasma energy of the free-valence-electron gas. The results indicate that $\frac{c}{a}$ may be predicted with an uncertainty of 0.1%.