Structural and mechanical characteristics of nanohydroxyapatite doped with zinc and chloride

Abstract

In this study, hydroxylapatite (HA) doped with Zn²⁺ and/or Cl⁻ ions was synthesised by precipitation method and sintered at 1100°C for 1 h. Densities of the samples were measured by the Archimedes method. Zn²⁺ addition increased the density significantly, while Cl⁻ increased the density insignificantly. Hydroxylapatite phase and inconsiderable amount of CaO phase were detected in some samples according to the X-ray diffraction results. Cl⁻ added samples (2·5 mol.-%) increased the hexagonal unit cell volume of HA. Characteristic PO³⁻₄ and OH⁻ bands of HA were detected in Fourier transform infrared spectroscopy. Cl⁻ related band was also observed at a wavenumber of 3497 cm⁻¹. Grain sizes of the samples decreased with Cl⁻ addition and increased with Zn²⁺ addition according to the SEM images. Zn²⁺ and Cl⁻ addition improved the microhardness of pure HA. Fracture toughness of the samples decreased with Cl⁻ and Zn²⁺ addition. When compared with other compositions, 2Zn2·5ClHA produced the best results in terms of mechanical properties.