Characterization of magnesium-substituted fluorapatites prepared by hydrothermal method

Sintering Behavior of Magnesium-Substituted Fluorapatite Powders Prepared by Hydrothermal Method

“…These results showed that the phosphorus environment undergoes little change during the incorporation of Mg. In agreement with this, the FTIR spectra of the as-synthesized powders showed only the characteristic bands of PO 4 group in an apatitic environment [ 18 ]. Thus, it seems that no amorphous phase was present in the powders, and if Mg was assumed to be adsorbed on the particle surface, as it is generally reported for HA and FA [ 14 , 25 ], it should take place in another form that cannot be detected either by XRD or NMR.…”

“…6: r Ca 2+ = 1.00 Å) [ 33 ]. The lattice contraction testifies that Mg was incorporated into the FA framework [ 18 ].…”

“…The first one starting from 600°C and 615°C and achieving a maximum at 696°C and 770°C for M 1 FA and M 2 FA, respectively, was probably caused by a particle rearrangement further to a better crystallisation of the powder. Indeed, it is well known that the incorporation of Mg into the apatite framework induces a decrease of the powders crystallinity [ 14 – 18 ]. The second step, corresponding to the major densification reached a maximum rate at about 944°C and 990°C for M 1 FA and M 2 FA, respectively.…”

“…Different methods can be used for synthesis the apatite such as solid-state reaction [ 26 ], coprecipitation [ 15 , 17 ], sol-gel [ 27 ] and hydrothermal synthesis [ 18 ]. Hydrothermal synthesis offers a relatively simple and effective way to prepare Well-crystallized powders.…”

“…In a earlier work, we reported the synthesis of the Magnesium-substituted fluorapatites with the general formula of Ca 10− x Mg x (PO 4 ) 6 F 2 (M x FA) (0 ≤ x ≤ 6) by the hydrothermal method and showed that the substitution limit is of about x = 2.5, (6.3 wt%) [ 18 ]; it is higher than that obtained by using the precipitation method [ 17 ]. The aim of this present study is to investigate the sintering behavior of these materials with x = 0, 1, and 2.…”