Cobalt-containing calcium fluorohydroxyapatites with properties of field-induced single-ion magnets

Resumo

Partially substituted calcium fluorohydroxyapatite Ca₁₀(PO₄)₆[(CoO₂)_xF_y(OH)_2−(2x+y)] samples were obtained by the solid state synthesis. The linear channels of the samples contain dioxocobaltate ions characterized under an external magnetic field by the slow relaxation of magnetization with the remagnetization energy barrier U_eff = 61–65 cm⁻¹≈2|D|, which coincides with the barrier for similar apatite samples containing no fluorine. Fluoride ions exert no significant effect on the magnetic properties of the dioxocobaltate ions but substantially decrease the concentration of paramagnetic cobalt.