Solid-phase steam-assisted synthesis of hydroxyapatite nanorods and nanoparticles

Shen, Shou Cang; Chia, Leonard; Ng, Wai Kiong; Dong, Yuan; Tan, Reginald B. H.

doi:10.1007/s10853-010-4691-1

Cited by 13 publications

(8 citation statements)

References 42 publications

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“…The natural bone model presents a combination of organic and inorganic phases with nanometer size (an average length of 50 nm and 25 nm in width) 3 . The small size of the apatite crystalite is a very important factor related with the biological and structural properties such as surface activity, dissolution rate, molding and sintering behavior [4][5][6][7] . In order to obtain nanoapatites out of the biological environment and similar to the one in bone, is very important to study how their properties change with the dimensions.…”

Section: Introductionmentioning

confidence: 99%

XRD, AFM, IR and TGA study of nanostructured hydroxyapatite

et al. 2012

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In this work, the synthetic hydroxyapatite (HAP) was studied using different preparation routes to decrease the crystal size and to study the temperature effect on the HAP nano-sized hydroxyapatite crystallization. X-ray diffraction (XRD) analysis indicated that all samples were composed by crystalline and amorphous phases . The sample with greater quantity of amorphous phase (40% of total mass) was studied. The nano-sized hydroxyapatite powder was heated and studied at 300, 500, 700, 900 and 1150 °C. All samples were characterized by XRD and their XRD patterns refined using the Rietveld method. The crystallites presented an anisotropic form, being larger in the [001] direction. It was observed that the crystallite size increased continuously with the heating temperature and the eccentricity of the ellipsoidal shape changed from 2.75 at 300 °C to 1.94, 1.43, 1.04 and 1.00 respectively at 500, 700, 900 and 1150 °C. In order to better characterize the morphology of the HAP the samples were also examined using atomic force microscopy (AFM), infrared spectrometry (IR) and thermogravimetric analysis (TGA).

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Section: Introductionmentioning

confidence: 99%

XRD, AFM, IR and TGA study of nanostructured hydroxyapatite

et al. 2012

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“…The hardness value calculated from Hoepfner's data (H 0 = 6.00 ± 0.7 GPa and b H = 6.03) [72] using Eq. (6) [73] found a maximum H value of 6.08 GPa, which is similar in magnitude to Hoepfner's P = 0 value [72] of H for polycrystalline bulk HA, although Shen et al did not specify a grain size. In addition, for bulk polycrystalline HA specimens sintered at 1,350°C in air, with a mean grain size of *7 lm and a porosity of 0.01, Muralithran [74] used Vickers indentation at a load of 1.96 N and obtained a mean hardness of *5.2 GPa.…”

Section: E H and Kc For Ha Specimens In This Studymentioning

confidence: 65%

Slow growth of microcracks in hydroxyapatite during aging

2012

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Hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 or HA) is a brittle material that is subject to environmentally assisted slow crack growth. While most slow crack growth studies are carried out after aging, this study examines the slow growth of radial cracks induced by Vickers indentation in dense HA (94 % of theoretical density) during aging in ambient air, where the observed crack growth is consistent with a process in which residual stress drives crack growth. For indentation loads of 0.98, 1.96, 2.94, and 4.91 N, the average radial crack length increased exponentially with time for indentation loads of 0.98, 1.96, 2.94, and 4.91 N, with crack lengths saturating within 1 h following indentation. However, no radial crack growth was observed for 9.81 N loads. The load dependence of radial crack growth is proposed to be linked to the partitioning of residual strain energy by the lateral crack growth, which has not been reported in the literature.

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“…Rasenack et al [60] demonstrated that the microcrystal forms of poorly water-soluble drugs could enhance their dissolution rates. Shen et al also found that nanocrystal [59] or amorphous [61] IBU had a higher bioavailability than crystalline IBU in bulk, because of a faster dissolution rate.…”

Section: Characterization Of the Aptes-modified And Ibu-loaded Halloymentioning

confidence: 99%