Infrarotspektroskopische und röntgenographische Untersuchungen von Bleihydroxylapatit,Bleioxyapatit und Bleialkaliapatiten

The infrared spectra of lead hydroxyapatite Pb₁₀(PO₄)₆(OH)₂, oxyapatite Pb₁₀(PO₄)₆O, and the lead alkaliapatites Pb₈M₂(PO₄)₆ (M = Na, K, Rb, T1) were investigated down to 200 cm^?1. There are significant differences between all these spectra. In the hydroxy- and oxyapatite spectrum one band is ascribed to the translational motion of the OH^? and O^2? ions, respectively. The thermal dependance of the dehydration of hydroxy to oxyapatite was studied by X-ray methods, both compounds forming a solid solution. The heat of decomposition of hydroxyapatite was found to be ΔH = 5 kcal/mole. Moreover, complete miscibilities could be shown to exist in the systems $\text{Pb}{}_8\text{Na}{}_2\text{(PO}{}_4\text{)}{}_6\text{Pb}{}_{10}\text{(PO}{}_4\text{)}{}_6\text{O}$ and $\text{Pb}{}_8\text{Na}{}_2\text{(PO}{}_4\text{)}{}_6\text{Pb}{}_{10}\text{(PO}{}_4\text{)}{}_6\text{(OH)}{}_2$, respectively.