W-band pulsed EPR and ENDOR investigations of X-ray irradiated nanoparticles of synthetic hydroxyapatite Ca₉Pb(PO₄)₆(OH)₂ are performed. It is shown that in the investigated species lead ions probably replace the Ca(1) position in the hydroxyapatite structure.

—A standard series of ceramic scaffolds for bone tissue regeneration with Kelvin architecture was developed, providing matrix water permeability not less than 900 Darcy and relative rigidity...

Calcium phosphate powder was synthesized at room temperature from aqueous solutions of ammonium hydrophosphate and calcium acetate without pH adjusting at constant Ca/P molar ratio 1.5. Phase composition of the as-synthesized powder depended on the precursors concentration: At 2.0 M of calcium acetate in the starting solution, poorly crystallized hydroxyapatite was formed, 0.125 M solution of calcium acetate afforded brushite, and the powders synthesized from 0.25–1.0 M calcium acetate solutions were mixtures of the mentioned phases. Firing at 1100 °C led to complete elimination of the reaction by-products, yet the phase composition of the annealed compacted samples was the following: When 2.0 M solution of calcium acetate was used, the obtained ceramics consisted of β-Ca₃(PO₄)₂, whereas at 0.125 to 1.0 M of calcium acetate, the ceramics was a mixture of β-Ca₃(PO₄)₂ and β-Ca₂P₂O₇. Synthesized calcium phosphate powders can be used as the powdered precursors for biocompatible bioresorbable composite ceramics production.