Specific surface free energy (SSFE) of
natural calcium fluorapatite from the same mother rock and synthesized barium
chlorapatite from the same lot was determined using contact angle of water and
with grown length of crystal face (h). The experimentally obtained SSFEs
have different values even for the same index faces of the different crystals. The SSFEs also have
wide distribution for each face of crystals. Observed SSFE is considered to be not only the SSFE of
ideally flat terrace face, but also includes the contribution of strep free
energy. Though the crystals we experimentally obtained were growth form, the
relationship between SSFE and h was almost proportional, which looks like
satisfying Wulff’s relationship qualitatively. The slope of SSFE versus h line shows the driving force of crystal growth, and the line for larger crystal
has less steep slope. The driving force of crystal growth for larger crystal is
smaller, which also means that the chemical potential is larger for larger
crystal. The individuality of crystals for the same lot can be explained by the
difference of the chemical potential of each crystal.
T. Suzuki and M. Oda, “Specific Surface Free Energy and the Morphology of Synthesized Ruby Single Crystals,” Journal of Crystal Growth, Vol. 318, No. 1, 2011, pp. 76-78. http://dx.doi.org/10.1016/j.jcrysgro.2010.11.058
R. N. Shimizu and N. R. Demarquette, “Evaluation of Surface Energy of Solid Polymers Using Different Models,” Journal of Applied Polymer Science, Vol. 76, No. 12, 2000, pp. 1831-1845.