Speaker
Description
Niobium and niobium-based oxides are attracting increasing interest because of their chemical and thermal stability, superconducting properties, and potential applications in catalysis, photocatalysis [1,2], and energy storage [3]. Niobium oxides and mixed titanium-niobium oxides exhibit rich structural chemistry, defect-driven electronic behaviour, and tunable optical and electrochemical properties. Nevertheless, their functional performance is often limited by low electronic conductivity, wide band gaps, and the large diversity of possible compositions and crystal structures. Non-stoichiometric oxygen-deficient phases may enhance electrical conductivity and solar-light absorption, while also creating new surface-active sites for electrochemical processes. In this context, femtosecond laser processing offers a versatile approach to the synthesis and modification of niobium-based materials, enabling localized energy deposition, non-equilibrium phase formation, controlled oxidation, and surface micro- and nanostructuring.
This work presents results on the design and modification of niobium-based materials using femtosecond lasers. First, ultrafast laser powder-bed processing is employed to produce layers of niobium oxides and titanium niobates directly from high-purity precursor powders [4]. By adjusting the laser irradiation parameters, the microstructure, oxygen deficiency, and crystalline phase composition of the resulting layers can be controlled (Figure 1a). This energy-efficient approach promotes the formation of functional niobium-based oxides, including oxygen-deficient Wadsley-Roth-type crystal structures relevant to photocatalytic and energy-storage applications.
Second, the femtosecond-laser modification of metallic niobium surfaces is investigated through the formation of laser-induced periodic surface structures (LIPSS) [5,6]. Under ambient conditions, periodic nanostructures are generated by controlling the laser fluence, pulse overlap, and number of accumulated pulses. In addition to surface texturing, laser irradiation induces localized oxidation, producing niobium oxide layers with different oxidation states, morphologies, and crystal structures (Figure 1b). Subsequent thermal treatments show that the initial laser-induced oxidation state affects the oxidation kinetics and oxide growth. These findings suggest that ultrafast laser irradiation may promote the formation of less common crystal structures. Overall, the results demonstrate the potential of femtosecond laser processing as a flexible tool for both the synthesis and surface modification of niobium-based materials.
FIGURE 1. (a) Real-colour optical microscopy images of femtosecond-laser-irradiated niobium oxide powders. (b) SEM image of a laser-processed region on a metallic niobium surface, showing the formation of cone-like structures.
Notes and References
[1] A. Calvo-Villoslada et al., Accepted in Ceramics International 2026, DOI: 10.1016/j.ceramint.2026.06.221
[2] A. Calvo-Villoslada et al., Nanomaterials 15, 846, 2025.
[3] A. Calvo-Villoslada et al., Materials Today Chemistry 47, 102860, 2025.
[4] B. Sotillo et al., Materials & Design 224, 111346, 2022.
[5] I. Gnilitskyi et al., Scientific Reports 7, 8485, 2017.
[6] A. Cubero et al., Applied Surface Science 508, 145140, 2020.