Presentations

Manganese-Substituted Hydroxyapatite Structures: Modeling and Experiment

Bystrov V.S., Paramonova E.V., Avakyan L.A.¹, Makarova S.V.², Bulina N.V.², Semenov S.V.³, Rubailo A.I.⁴

Institute of Mathematical Problems of Biology RAS – branch of Keldysh Institute of Applied Mathematics RAS, 142290 Pushchino, Russia

¹Physics Department, Southern Federal University, Rostov-on-Don, Russia

²Institute of Solid State Chemistry and Mechanochemistry SB RAS, Novosibirsk, Russia

³L.V. Kirensky Institute of Physics SB RAS, Krasnoyarsk, Russia

⁴Krasnoyarsk Center for Collective Use SB RAS, Krasnoyarsk, Russia

Hydroxyapatite (HAP) is a mineral component of bones and teeth, has good biocompatibility and therefore is mainly used in medicine for bone tissue restoration. At the same time, HAP is increasingly used in other areas, including magnetic resonance imaging and local magnetic hyperthermia in the treatment of cancer tumors [1], due to the possibility of including iron, manganese, etc. ions with magnetic properties in their composition. The crystal structure of HAP is quite flexible and easily integrates various ions, which affects the properties of HAP. One of the important such cations is manganese. This paper presents the results of modeling the Mn-HAP lattice with different numbers of Mn/Ca substitutions in different positions, obtained using high-precision calculations by the density functional theory with hybrid functionals [2]. Experimental data on the synthesis of Mn-HAP by a mechanochemical method are also presented. The calculated and experimental data show good agreement: the unit cell parameters and the volume decrease with increasing Mn/Ca substitutions [3], which corresponds to the ionic radii of Ca and Mn. These results are similar to those obtained for Mg/Ca substitutions in Mg-HAP [4]. However, additional electron energy levels appear inside the band gap Eg of Mn-HAP, whereas in Mg-HAP there are no levels inside the band gap, only the width Eg changes. With the introduction of Mn, the photoexcitation energy changes, and its effective value Eg* becomes smaller than the band gap width Eg in pure HAP. Magnetic properties of HAP-Mn also appear (up to 5 magn. Bohr/cell for 1 Mn) proportional to the amount of introduced Mn. Experimental measurements of the magnetic properties of Mn-HAP samples on a VSM 8604 vibration magnetometer yielded magnetization values ​​of up to 0.3 emu/g in a field of 1.5 T at a temperature of 300 K. The results obtained indicate good prospects for possible applications of the created Mn-HAP structures.

References

1. Tampieri A., et al. Acta Biomater., V. 8, 2012, P. 843–851.

2. Bystrov V., Paramonova E., et al. Nanomaterials, V. 11, 2021, P. 2752.

3. Bystrov V.S., et al. Bulletin of the Russian Academy of Sciences: Physics, 2024, Vol. 88, No. 5, pp. 745–751.

4. Bystrov V.S., Paramonova E.V., Avakyan L.A., et. al., Materials, Vol. 16, 2023, P. 5945.

• abstract in Russian (PDF)