Substituted hydroxyapatites for biomedical applications: A review

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…Usually, the ion-substituted CaPO 4 are of a non-stoichiometric nature with just a partial ionic substitution and there are too many of them to be described here. Currently, this is a hot investigation topic; therefore, the readers are referred to the special literature (Pan and Fleet 2002;Rey et al 2006;Kannan et al 2008;Boanini et al 2010b;Shepherd et al 2012;Adzila et al 2012;Grigg et al 2014;Š upová 2015). In addition, there is a very good review, in which the structures of more than 75 chemically different apatites have been discussed (White and Dong 2003).…”

“…Last, one should very briefly mention on existence of carbonated HA (Lafon et al 2008;Tonegawa et al 2010;Yahia and Jemal 2010;Silvester et al 2014;Fleet 2015), chlorapatite (Kannan et al 2007;García-Tuñón et al 2012;Zhao et al 2013), as well as on a great number of CaPO 4 with various ionic substitutions (CaPO 4 with dopants) (Pan and Fleet 2002;Rey et al 2006;Kannan et al 2008;Boanini et al 2010b;Shepherd et al 2012;Adzila et al 2012;Grigg et al 2014;Š upová 2015). In principle, any ion in CaPO 4 might be substituted by other ion(s).…”

Fabrication and biological evaluation of hydroxyapatite ceramics including bone minerals

“…In wet synthesis, CO 3 2¹ ions are substituted mainly at the positions of the PO 4 3¹ ions of apatite, and the lattice constant of the a-axis of HAp decreases. 22) The lattice constant of the a-axis of bone HAp was smaller than that of pure HAp. As the desired amount of CO 3 2¹ ions was added in the synthesis of the bone HAp powders, more CO 3 2¹ ions were incorporated in the apatite structure than in pure HAp, and the lattice constant of the a-axis decreased further as a result.…”

Fabrication of Potassium-Substituted Hydroxyapatite Ceramics via Ultrasonic Spray-Pyrolysis Route

“…Although there was almost no difference depending on the potassium contents in the case of powders, the peak intensity of OH -groups at 630 and 3570 cm −1 of KAp(3.75) and (KAp5.0) was lower than that of pure HAp and KAp(2.5). Substitution of monovalent cations like Na + and K + ions cause a charge imbalance that can be neutralized by creating supplementary vacancies, or by the occurrence of simultaneous substitutions of cations and anions without the formation of any vacancy or loss of the charge balance 15 . Since carbonate ions were not detected in KAp ceramics, the decrease in the OH -band observed at KAp(3.75) and KAp(5.0) may have resulted in the formation of OH vacancies.…”