title: Physico-mechanical and morphological features of zirconia substituted hydroxyapatite nano crystals.
abstract: Zirconia doped Hydroxyapatite (HAP) nanocrystals [Ca10(PO4)6-x(ZrO2)x(OH)2]; (0 ≤ x ≤ 1 step 0.2) were synthesized using simple low cost facile method. The crystalline phases were examined by X-ray diffraction (XRD). The crystallinity percentage decreased with increasing zirconia content for the as-synthesized samples. The existence of zirconia as secondary phase on the grain boundaries; as observed from scanning electron micrographs (FESEM); resulted in negative values of microstrain. The crystallite size was computed and the results showed that it increased with increasing annealing temperature. Thermo-gravimetric analysis (TGA) assured the thermal stability of the nano crystals over the temperature from room up to 1200 °C depending on the zirconia content. The corrosion rate was found to decrease around 25 times with increasing zirconia content from x = 0.0 to 1.0. Microhardness displayed both compositional and temperature dependence. For the sample (x = 0.6), annealed at 1200 °C, the former increased up to 1.2 times its original value (x = 0.0).
authors.affiliation: Physics Department, Faculty of Science, Zagazig University, Egypt.
authors.forename: S F
authors.initials: SF
authors.lastname: Mansour
authors.affiliation: Materials science and nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences (PSAS), Beni-Suef University, Egypt.
authors.forename: S I
authors.initials: SI
authors.lastname: El-Dek
authors.affiliation: Materials Science Lab.(1), Physics Department, Faculty of Science, Cairo University, Giza, Egypt.
authors.forename: M K
authors.initials: MK
authors.lastname: Ahmed