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Item type:Publication, Access status: with files , Printing photonic-based thermal barrier coatings onto metal alloy(Nature Publishing Group, 2025-12-01); ; ; ; Reflective coatings based on photonic crystals and photonic glasses are usually produced by traditional colloidal self-assembly techniques characterised by limited control over the deposition surface and lengthy processing times. The emergence of Additive Manufacturing combined with Colloidal Assembly (AMCA) has enabled fast and precise deposition of homogeneous photonic structures, whilst circumventing issues such as the undesired coffee-ring effect. However, the application of this technique was limited to flat substrates. This study investigates the AMCA of ceramic-based colloidal structures onto metallic curved surfaces, relevant to the field of thermal barrier coatings (TBCs). Our results demonstrate the homogeneous ceramic-based photonic glass coatings can be AMCA-printed on different substrates only when a conscious surface charge matching between the colloidal particles and the substrates is made. It also demonstrates the importance of controlling the contact angle of the suspension on the substrates and the printing geometry strategy, differing from traditional direct writing. We further demonstrate the versatility of this method by printing highly porous three-dimensional gadolinium zirconate structures onto curved Inconel substrates. These coatings are engineered for their use as reflective “photonic-based” thermal barrier coatings (rTBCs), capable of suppressing both radiative and conductive heat transport. The resultant AMCA-printed Gd2Zr2O7 rTBCs outperform state-of-the-art TBCs in terms of their reflectance properties and provide a reliable thermal protection to the underlying Inconel alloy, lowering its temperature by about 150 °C in a torch experiment.Publicationtype: Journal Article68 23 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Water-based cylindrical metamaterials with radial anisotropy for electric field enhancement and suppression(META Conference, 2025-07); ; ; ; In this paper, we study how a cylindrical shell made from a radially anisotropic material can modify the electric field inside an isotropic core, either by enhancing or suppressing it. We present a water-air metamaterial that enhances electric fields by 10 dB across a broad frequency range.Publicationtype: Conference Paper97 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , On the combination of pyrolysis and plasma to create Parylene C thin films(VDE Verlag, 2025); ; ; ; Pyrolysis for Parylene C deposition is a safe way to produce biocompatible hermetic thin films above 1 µm. For thin films below that thickness, the use of plasma is a well-researched process, but these films lack biocompatibility. With the combination of pyrolysis and Argon-plasma (30 W, 50 W), a new process was used to create Parylene C thin films and investigate thickness, Young’s Modulus, FTIR spectra, and the surface via SEM. The use of 50 W Argon-plasma shows an increase of thickness (1.6 µm) and Young’s Modulus (26.34 GPa) compared to pyrolysis (t=0.9 µm, E=7 GPa).Publicationtype: Conference Paper97 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Switchable 3D Photonic Crystals Based on the Insulator-to-Metal Transition in VO2(American Chemical Society (ACS), 2024-12-11); ; ; Photonic crystals (PhCs) are optical structures characterized by the spatial modulation of the dielectric function, which results in the formation of a photonic band gap (PBG) in the frequency spectrum. This PBG blocks the propagation of light, enabling filtering, confinement, and manipulation of light. Most of the research in this field has concentrated on static PhCs, which have fixed structural and material parameters, leading to a constant PBG. However, the growing demand for adaptive photonic devices has led to an increased interest in switchable PhCs, where the PBG can be reversibly activated or shifted. Vanadium dioxide (VO2) is particularly notable for its near-room-temperature insulator-to-metal transition (IMT), which is accompanied by significant changes in its optical properties. Here, we demonstrate a fabrication strategy for switchable three-dimensional (3D) PhCs, involving sacrificial templates and a VO2 atomic layer deposition (ALD) process in combination with an accurately controlled annealing procedure. The resulting VO2 inverse opal (IO) PhC achieves substantial control over PBG in the near-infrared (NIR) region. Specifically, the synthesized VO2 IO PhC exhibits PBGs near 1.49 and 1.03 μm in the dielectric and metallic states of the VO2 material, respectively, which can be reversibly switched by adjusting the external temperature. Furthermore, a temperature-dependent switch from a narrow-band NIR reflector to a broad-band absorber is revealed. This work highlights the potential of integrating VO2 into 3D templates in the development of switchable photonics with complex 3D structures, offering a promising avenue for the advancement of photonic devices with adaptable functionalities.Publicationtype: Review Article26 23 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , On the applicability of the Maxwell Garnett effective medium model to media with a high density of cylindrical pores(Optica Publishing Group, 2024-04-01); ; ; ; The optical properties of dielectric materials with subwavelength cylindrical pores are commonly described by effective medium models. We compare the Maxwell Garnett and the Bruggeman effective medium models for porous silicon with simulations and experiments for the case of polarization orthogonal to the pore axis. The Maxwell Garnett model matches the results of the simulations even up to very high porosities. An experimental study of the effective permittivity of macroporous and mesoporous silicon is conducted by analyzing the Fabry-Pérot oscillations in the long-wavelength limit. These experimental results are also consistent with the Maxwell Garnett model. We advocate using this model for media with cylindrical pores in the future.Publicationtype: Journal Article36 56 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Maxwell Garnett effective medium model for dielectric materials with high filling fraction of cylindrical poresThe optical properties of dielectric materials with subwavelength cylindrical pores are commonly described by effective medium models. We compare the Maxwell Garnett and the Bruggeman effective medium model for porous silicon with simulations to study their applicability. We found that the Maxwell Garnett model matches the results of the simulations even up to high porosities and discuss the reasons for this. We advocate using this model for membranes with cylindrical pores in the future.Publicationtype: Conference Paper45