Surface structural controls on trace element incorporation during growth

Surface structural controls on trace element incorporation during growth 

The dotted lines indicate the sector associated with the prism face and the subsector of the basal vicinal face of the hillock is shaded, (b) A DIG photomicrograph of an actual hillock on the (100) face of a fluorapatite from the Golconda Mine, Minas Gerais, Brazil. Image is -666 pm vertical. [Modified after Rakovan and Reeder (1996).] 

In the apatites from Japan, Akizuki et al. (1994) found biaxial optical character with domains of different optical orientation and 2V (Fig. 27). Although the optical properties indicate a monoclinic or triclinic structure, electron and X-ray diffraction data showed no reflections inconsistent with / 63/m symmetry or that indicate a superstructure. They postulated that the dissymmetrization is due to ordering of OH and F (Hughes and Rakovan, this volume) along growth steps during incorporation. 

With the rapid advances in nanotechnology, including new methods for direct observation and analysis of surfaces at the nanometer and atomic scales, more insights pertaining to these and other unanswered questions will be made. 

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