The variance of diffractometer-collected diffraction intensities is discussed in terms of instrumental instability and uncertainties in the parameter used to bring the intensities to a common scale. It is shown that the inconsistent and]or divergent behavior of the reflections used as standards contributes in a major way to the uncertainty in the scaling parameter and can often account for the largest portion of the variance in excess of the Poisson contribution for reflections with large intensities.

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Amorphous Zr−Ti hydrous oxide submicrometer spheres were employed in hydrothermal syntheses of PbZr0.7Ti0.3O3 heteroepitaxial thin films on single-crystal SrTiO3 substrates. Reactions utilizing processing variables that included precursor concentration (0.1−0.4 m), KOH concentration (6−12 m), and time (24−60 h) were carried out at 150 °C to evaluate the effect of this precursor on the formation of an epitaxial film. Selected experiments were also conducted to examine how this spherical precursor compares with two other precursor systems, that is, nanostructured amorphous Zr−Ti hydrous oxide prepared by coprecipitation at room temperature, and a mixture of crystalline TiO2 and amorphous ZrO2·nH2O obtained from soluble ZrOCl2·8H2O. On the basis of the results of X-ray diffraction and electron microscopy, precursor choice, precursor concentration, and KOH mineralizer concentration have a significant effect on the quality, composition, and morphology of the film.

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The structures of two derivatives of bicyclo[3,3,1]nonane-2,4,9-trione were solved by direct methods. The structures of clusianone, C33H4204, and trimethylated catechinic acid, C1sH2006, were refined by standard least-squares techniques to weighted R(F) values of 0-038 and 0.046 respectively using diffractometer data. The two molecules are compared and unusually long C(sp3)-C(sp 3) bonds are discussed. Clusianone contains a 1"603 (4) A carbon--carbon bond.