The X-ray scattering pattern of hexagonal ZnO at 298°K, within a reciprocal lattice hemisphere of radius (sin 0)/2= 1.02 A,-~ containing the polar c* axis as diameter, was measured with PEXRAD. The integrated intensities of 374 reflections, resulting in 141 independent Fracas, were determined. The structure was refined by the method of least squares: the final agreement index R was 0"0378. The sole position parameter is u = 0.3825 + 0.0014. The predicted value is 0.3799, obtained from the measured c/a ratio of 1.602107 and assuming equal Zn-O distances in the ZnO4 tetrahedra. The characteristic Debye temperature O, in isotropically vibrating ZnO, is 370°K. The absolute configuration of the ZnOa tetrahedra is such as to present a triangular oxygen face normal, directed from the face, toward the positive sense of the piezoelectric polarization as induced by a compressive stress applied along the polar axis. The piezoelectric coefficients are predicted to have a small temperature dependence.
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