Inducing Electrical Pathways on Nb ₂ O ₅ Ceramics through Laser Surface Modification

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Nowadays, there is an increasing interest in developing sensors on the surfaces of ceramic materials, given their remarkable durability and stability in harsh and demanding environments. However, their generally low electrical conductivity can limit their application as sensors. As such, the present study explores the use of a continuous-wave CO 2 laser to induce localized transformations in insulating Nb 2 O 5 ceramic surfaces to generate electrically conductive pathways. X-ray diffraction analyses through Rietveld refinement and density functional theory calculations confirmed that the laser treatment, rather than a phase transformation, induced oxygen vacancies, which introduced donor states and narrowed the bandgap, leading to enhanced electrical conductivity. Furthermore, the interaction of the laser with the base material enhances densification, grain growth, and crystallization, while also inducing preferential grain orientation, all of which contribute to the significant improvement in electrical conductivity. The effects of laser processing parameters on pathway morphology, grain size, porosity, and electrical conductivity were studied, demonstrating that these characteristics can be tuned for specific applications. By adjusting the laser processing parameters, it was possible to obtain a maximum pathway width of 0.80 ± 0.02 mm, a depth of 0.41 ± 0.02 mm, and an electrical conductivity of 20 ± 2 S/m, an enhancement of up to 8 orders of magnitude compared to the raw material. Additionally, comparisons between niobium and iron oxide samples allowed the assessment of the role of laser irradiation in promoting localized conductive pathways on insulating ceramics. These findings highlight the potential of laser processing for tailoring the electrical properties of ceramic material surfaces, with promising applications in ceramic-based sensors for temperature, humidity, and water-level monitoring.