Effect of surfactant and heat treatment on morphology, surface area and crystallinity in hydroxyapatite nanocrystals

Characteristics and properties of hydoxyapatite derived by sol–gel and wet chemical precipitation methods

“…Meanwhile, Sooksaen et al [24] indicated that HA powders calcined beyond 800 1C showed the presence of CaO when HA nanopowders were synthesized via wet chemical process by using Ca(NO 3 ) 2 Á 4H 2 O and (NH 4 ) 2 HPO 4 as Ca and P precursors. CaO is actually an impurity in most HA derived via sol-gel, which is due to the decomposition of calcium nitrate that remains either partially reacted or unreacted in the gel during the sintering process [15,22,26]. However, in the present study, CaO was not detected by XRD until 1000 1C for both HA-Wp and HA-Sg powders.…”

“…As a result, the powder reactivity of HA-Wp could be significantly enhanced because of the smaller crystallite size, which consequently increases the specific surface area to volume ratio [24]. In addition, the HA-Wp powder characteristic also more likely correlates to the properties of bone mineral crystal, namely, low crystallinity with an extremely large surface area [25,26].…”

“…Instead, the formation could be due to the formation of an intermediate phase, oxyapatite, which shows the gradual loss of the radical OH À (dehydroxylation) when heated at atmospheric conditions [19]. According to Fathi et al [21], pure HA powder derived from the sol-gel was only obtained after the powder was subjected to calcination at 600 1C, whereas the powder could be decomposed into β-TCP and CaO at 700 1C [21,26]. However, in the present work, the characteristic of pure HA was achieved by as-synthesized HASg after drying the powder at a relatively low temperature of 340 1C (Fig.…”

Effect of Na+ and NaOH concentrations on the surface morphology and dissolution behavior of hydroxyapatite

“…6(b, c)). The asymmetric stretching vibration ν 3 of the P-O bond is characterized by a band that is split in two peaks: at 1094 (ν 3a ) and 1032 cm À 1 (ν 3b and ν 3c ) [28][29][30]. The bands at 604 (ν 4a ) and 563 cm À 1 (ν 4b and ν 4c ) in Fig.…”

Effect of Hydroxyapatite Reinforced with 45S5 Glass on Physical, Structural and Mechanical Properties

“…The detection of two main bands at 550 cm -1 and 1020 cm -1 as well as a weak shoulder band at 450 cm -might be attributed to PO4 tetrahedral. The detection of bands at 450 cm , 550 cm , and 1020 cm were attributed to the double degenerated O-P-O bending modes, v2, triple degenerated asymmetric O-P-O bending modes, and triple degenerate asymmetric P-O stretching mode16 . respectively.…”