Bioactive apatite-wollastonite glass ceramics coating on metallic titanium for biomedical applications: effect of boron.

Metallic titanium (Ti) implant surfaces need improvement for bioproperties and antibacterial behavior. For this purpose, a new boron-doped bioactive apatite-wollastonite (AW) coating was successfully developed on the Ti plate surface. The effects of boron addition on the microstructure, mechanical properties, and bioproperties of the AW coating were investigated. With the addition of boron (B), the AW coating morphology became less porous and compact. In terms of bio properties, the rate of apatite formation increased with the addition of B, and the cell viability rate increased from approximately 66-81%. B addition increased the elastic modulus of the AW coating from about 24-46 GPa and increased its hardness about 2.5 times. In addition, while no antibacterial activity was observed in the AW coating, the addition of boron slightly introduced antibacterial properties. The novel AW/B composite coating obtained is promising for Ti implant surfaces.

Sulfur doped Li1.3Al0.3Ti1.7(PO4)3 solid electrolytes with enhanced ionic conductivity and a reduced activation energy barrier.

Recently, tailored synthesis of solid electrolytes satisfy multiple challenges, i.e. high ionic conductivity and wide (electro)chemical stability window is of great interest. Although both oxide- and sulfide-based solid electrolytes have distinguished merits for meeting such concerns separately, a new solid electrolyte having the excellent aspects of both materials is pursued. Herein, we report the synthesis of a sulfur-doped Li1.3Al0.3Ti1.7(PO4)3 (LATP) solid electrolyte with a NASICON crystal structure that combines elevated ionic conductivity with intrinsic stability against an ambient atmosphere. Sulfur doping was carried out using sulfur-amine chemistry and the system was characterized by XRD, Raman, XPS, ICP-OES, and EDS analyses. Bader charge analysis was carried out with the aid of density functional theory calculations to characterize charge accumulation in the local environment of the bare and sulfur doped LATP structures. Our results indicate that the partial replacement of oxygen with sulfur yields higher ionic conductivity due to the lower electronegativity of sulfur compared to oxygen, which reduces the attraction of lithium ions. The enhanced ionic conductivity of LATP is attributed to a decreased lithium ion diffusion activation energy barrier upon sulfur doping. Compared to bare LATP, the as-prepared sulfur doped LATP powders were shown to decrease the activation energy barrier by 10.1%. Moreover, an ionic conductivity of 5.21 × 10-4 S cm-1 was obtained for the sulfur doped LATP powders, whereas bare LATP had an ionic conductivity of 1.02 × 10-4 S cm-1 at 40 °C.