Affinity of the Interface between Hydroxyapatite (0001) and Titanium (0001) Surfaces: A First-Principles Investigation

Abstract

A basic understanding of the affinity between the hydroxyapatite (HA) and α-Ti surfaces is obtained through electronic structure calculations by first-principles method. The surface energies of HA(0001), HA (011̅0), HA (101̅1), and Ti(0001) surfaces have been calculated. The HA(0001) presents the most thermodynamically stable of HA. The HA/Ti interfaces were constructed by two kinds of interface models, the single interface (denoted as SI) and the double-interface (denoted as DI). Two methods, the full relaxation and the UBER, were applied to determine the interfacial separation and the atomic arrangement in the interfacial zone. The works of adhesion of interfaces with various stoichiometric HA surfaces were evaluated. For the HA(0001)/Ti(0001) interfaces, the work of adhesion is strongly dependent on the chemical environment of the HA surface. The values are -2.33, -1.52, and -0.80 J/m(2) for the none-, single-, and double-Ca terminated HA/Ti interfaces, respectively. The influence of atomic relaxation on the work of adhesion and interface separation is discussed. Full relaxation results include -1.99 J/m(2) work of adhesion and 0.220 nm separation between HA and Ti for the DI of 1-Ca-HA/Ti interface, while they are -1.14 J/m(2) and 0.235 nm by partial relaxation. Analysis of electronic structure reveals that charge transfer between HA and Ti slabs occurs during the formation of the HA/Ti interface. The transfer generates the Ti-O or Ti-Ca bonds across the interface and drives the HA/Ti interface system to metallic characteristic. The energetically favorable interfaces are formed when the outmost layer of HA comprises more O atoms at the interface.

Density Functional Theory Study of Interface Interactions in Hydroxyapatite/Rutile Composites for Biomedical Applications

“…It should be noted that the precise stacking position also has an influence on the resulting work of adhesion values. Previously, rather similar values of the work of adhesion, in the ranges of −0.01 and −1.99 J m –2 , were obtained for the HA(0001)/Ti(0001) interface system using DFT by Sun et al…”

Interface Alloying Design to Improve the Dispersion of TiB2 Nanoparticles in Al Composites: A First-Principles Study

“…To investigate their interfacial bonding strength as well as interface stability, the interfacial distance ( d 0 ) and the work of adhesion ( W ad ) are employed. The work of adhesion ( W ad ) is defined as the following − where E slab Al and E slab TiB 2 are the total energies of two six-layer Al(111) surface slabs and a nine-layer TiB 2 (0001) surface slab with the same lattice parameters of their relaxed interface models, respectively; E interface is the energy of the interface model after fully relaxed; 2 A represents the total area of two interface regions in each interface model (i.e., two identical interfaces at the top and bottom of the model).…”

Effect of van der Waals interactions on the adhesion strength at the interface of the hydroxyapatite–titanium biocomposite: a first-principles study

“…Interactions at the interface lead to charge redistribution due to electronic hybridization between the orbitals of the coating and the substrate. Therefore, for gaining a better insight in the inuence of Si doping in the a-HAP structure with and without dispersion DFT on the electronic interactions at the studied interfaces, the CDD was evaluated as follows: 41 Dr(r) ¼ r a-HAP/a-TiO 2 (r) À r a-HAP (r) À r a-TiO 2 (r),…”