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In this study, hydroxyapatite with the substitution of calcium cations by iron and phosphate by silicate groups was synthesized via a mechanochemical method. The as-prepared compounds have the general formula Ca10−xFex(PO4)6−x(SiO4)x(OH)2−xOx/2 with x = 0–1.5. The thermal stability of the as-prepared compounds was studied by ex situ annealing of powders in a furnace. It has been established that, at 800 °C for x ≤ 0.5, a partial decomposition of the substituted apatites occurs with the formation of the β–Ca3(PO4)2 phase. At high “x” values, the formation of this phase starts at the lower temperature of 700 °C, followed by the formation of Fe2O3 at 900 °C. The introduction of iron and silicate ions into the hydroxyapatite lattice was shown to decrease its thermal stability.

In this study, hydroxyapatite with the substitution of calcium cations by iron and phosphate by silicate groups was synthesized via a mechanochemical method. The as-prepared compounds have the general formula Ca10−xFex(PO4)6−x(SiO4)x(OH)2−xOx/2 with x = 0–1.5. The thermal stability of the as-prepared compounds was studied by ex situ annealing of powders in a furnace. It has been established that, at 800 °C for x ≤ 0.5, a partial decomposition of the substituted apatites occurs with the formation of the β–Ca3(PO4)2 phase. At high "x" values, the formation of this phase starts at the lower temperature of 700 °C, followed by the formation of Fe2O3 at 900 °C. The introduction of iron and silicate ions into the hydroxyapatite lattice was shown to decrease its thermal stability. [ABSTRACT FROM AUTHOR]

Abstract: We have successfully fabricated YBa2Cu3O y (Y123) and GdBa2Cu3O y (Gd123) films on SrTiO3 substrates by the ex situ heat treatment of co-evaporated Y–BaF2–Cu and Gd–BaF2–Cu precursor films prepared by electron beam deposition technique without water vapor. T c and J c of the Y123 film were 91.6K and 0.95MAcm−2 at 77K at self-field, respectively. The Gd123 film showed T c of 93.4K and J c of 1.5MAcm−2 at 77K at self-field. It was found that the surface morphology of the Y123 and the Gd123 films depended on the partial oxygen pressure during the heat treatment. [Copyright &y& Elsevier]