Atomic layer deposition of barium titanate coatings for the controlled tuning of piezoelectric surface activity on titanium-based implant materials

• Applicant: Dr.-Ing. Phil Goldberg
• Subject Area: Coating and Surface Technology ; Biomaterials ; Synthesis and Properties of Functional Materials
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 554832088

The objective of the proposed project is to generate bioactive surfaces of titanium-based implants for biomedical applications. The surface of the implants will be functionalized with a piezoelectric BaTiO3 coating. Due to the piezoelectric reactions on their surface, the implants are able to provide surface charges without an external voltage source when subjected to mechanical stress or loading. In this way, they can significantly improve osseointegration as well as continuously modulate cellular functionalities and support antimicrobial processes by electrical stimulation. An innovative coating method called the atomic layer deposition (ALD) is considered for the fabrication of the piezoelectric BaTiO3 thin films with their tetragonal phase fraction on different titanium alloy substrates. Compared to conventional coating processes such as molecular beam epitaxy and physical vapor deposition, the ALD not only outperforms with its high conformity (coating profile adapts to the complex implant geometries), but also with its good process control, scalability and low process temperatures. Since the ALD approach is being used for this purpose for the first time and the resulting BaTiO3 thin film on titanium-based substrate material has hardly been investigated in terms of its piezoelectric properties to date, a comprehensive scientific study is to be carried out in the context of the project. The research work includes the adjustment of process parameters for the synthesis of BaTiO3 thin films and a detailed material characterization of these BaTiO3-coated titanium alloy samples using surface analytical methods to determine the structural and physicochemical properties of the coating material. The piezoelectric properties will be analyzed using scanning probe microscopy and capacitance-voltage measurement methods, which enable, among others, the mapping of ferroelectric domains and ferroelectric hysteresis. Another aim is to identify relationships between the microstructural properties and the resulting morphology of the coating. In addition, the influence of the coating properties (depending on the layer thickness) on the piezoelectric properties of the BaTiO3 thin film will be investigated and evaluated. A fundamental understanding of these relationships and the selection of a suitable processing strategy support the development of concepts for the production of thin films for specific applications. Using the most suitable coating strategies, initial steps will be made on a laboratory scale to evaluate the transferability of ALD processing to complex implant shapes and, based on this, possible upscaling approaches for industrial applications will be developed.

• DFG Programme: Research Grants