REGULARITIES OF NICKEL- АND CARBONATE- CONTAINING CALCIUM PHOSPHATES FORMATION

• Datum: 2025
• Hauptverfasser: Slobodyanik , Mykola, Bebkevich, Olha, Strutynska, Nataliia
• Format: Artikel
• Sprache: English
• Veröffentlicht: V.I.Vernadsky Institute of General and Inorganic Chemistry 2025
• Online Zugang: https://ucj.org.ua/index.php/journal/article/view/700
• Назва журналу: Ukrainian Chemistry Journal

The regularities of nickel- and carbo­nate-con­taining calcium phosphates formation were investigated in an aqueous solution of the system Сa2+ - Ni2+  - PO43- - CO32- - NO3- at the molar ratios Сa2+ : Ni2+ : PO43-: CO32- = (10-х-у/2) : х : (6-у) : у, (for the values of x = 0.05, 0.1, 0.5, 1.0; у = 0 or 0.5) at room temperature with their subsequent heating to a temperature of 600 °С for 2 hours. The conditions for the formation of biphasic calcium phosphates (a mixture of phases based on Са10(РО4)6(ОН)2 and β-Са3(РО4)2) as well as monophasic apatite-related calcium phosphates were established. The crystallite sizes of calcium phosphate synthesized in systems without the addition of carbonate anions are within 25–30 nm, while the addition of carbonate anions to the initial solution at a molar ratio of PO43-/СО32- = 11 and an increase in the content of nickel cations (an increasing of value of x from 0.05 to 0.5) led to a decrease in the particle size of doped hydroxyapatites from 46 nm to 21 nm. The calculated lattice parameters for apatite-type calcium phosphates which belong to the hexagonal system, space group P63/m, are within the values: a = 9.41–9.43Å, c = 6.88–6.89 Å correlate with the degree of substitution of calcium cations by nickel cations in the cationic sublattice and phosphate by carbonate in the anionic position for hydroxyapatites. For phases based on β-Са3(РО4)2 (trigonal system, space group R3c) in the composition of biphasic calcium phosphates, the calculated lattice parameters (а = 10.36 Å, c = 37.22 Å) are some smaller than those corresponding to β-Са3(РО4)2, that indicates the doping of both types of phosphates with nickel cations. The position of the vibrational modes of carbonate groups in the frequency range 1365–1460 cm-1 confirms the B type of substitution in the anionic sublattice of apatite-type calcium phosphate. The obtained results can be used in the development of catalysts based on nanoparticles of modified with carbonate-anions apatite-related calcium phosphates, which contain up to 3 wt% nickel cations.