Nanoscale colour control: W–O graded coatings deposited by magnetron sputtering

Polcar, Tomáš; Kubart, Tomáš; Malainho, E.; Vasilevskiy, Mikhail; Parreira, N.M.G.; Cavaleiro, A.

doi:10.1088/0957-4484/19/39/395202

Cited by 4 publications

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“…These coatings can be applied through various techniques, such as painting [ 1 , 2 ], electrochemical deposition [ 3 , 4 , 5 ], chemical vapor deposition (CVD) [ 6 ], and physical vapor deposition (PVD) [ 7 , 8 , 9 , 10 ], among others. PVD techniques are a commonly employed choice across different industries for aesthetic enhancement, such as metalizing components, especially in the automotive sector [ 11 , 12 ], or applying them to building glazings [ 13 ].…”

Section: Introductionmentioning

confidence: 99%

Germanium-Based Optical Coatings for Aesthetic Enhancement with Low Radiofrequency Attenuation

Carretero,

Chueca,

Alonso

2024

Nanomaterials

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This work focused on developing optical coatings for decorative applications that remain transparent in the radiofrequency range. To achieve this, a combination of dielectric material (silicon-aluminum nitride, SiAlNx) and low-electrical-conductivity semiconductor material (germanium) was utilized. Germanium plays a crucial role in providing absorption in the visible spectrum, facilitating the design of coatings with various aesthetic appearances, while allowing for control over their transmittance. The optical properties of thin germanium layers were thoroughly characterized and leveraged to create multilayer designs with diverse aesthetic features. Different multilayer structures were designed, fabricated, and optically characterized, resulting in coatings with metallic gray, black, or various colors in reflection, while retaining the ability to transmit visible light for illumination and signaling applications. Finally, the radiofrequency attenuation of the developed coatings was measured, revealing negligible attenuation; this is in stark contrast to the metallic coatings used for decorative purposes, which can attenuate by up to 30 dB.

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Section: Introductionmentioning

confidence: 99%

Germanium-Based Optical Coatings for Aesthetic Enhancement with Low Radiofrequency Attenuation

Carretero,

Chueca,

Alonso

2024

Nanomaterials

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“…The pallet of colours exhibited by WO 3 coatings is due to interferometric effects. Recently, it was shown that playing with the gradient of the chemical composition of W-O layers it was possible to tune the global colour of the coatings, which made this system an attractive candidate for decorative applications [3].In this study the microstructural characterization of W-O coatings by transmission and scanning electron microsocopies (TEM and SEM, respectively) are presented. The coatings were deposited by reactive magnetron sputtering in RGPP mode (reactive gas pulsing process) [4].…”

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“…This information is revealed to be fundamental for modelling the optical behaviour of the multilayer, since other characterization techniques (e.g. Auger spectroscopy analysis after progressive in-depth etching of the sample) do not allow to establish directly the correspondence between the chemical composition and the depth at which the analysis is being performed [3]. …”

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Electron microscopy characterization of W-O multilayers

Parreira¹,

Polcar²,

Pei³

et al. 2009

Microsc Microanal

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In the decorative field, besides the optical characteristics needed for achieving desired colours, the material should have suitable properties able to assure the daily use of the component without significant degradation [1]. Oxides are well known materials with a high wear and corrosion resistance which make them a preferential choice of coatings for environmental protection. However, the intrinsic colours possible to be achieved in a single oxide system are very limited. For example in W-O system, besides the different tonalities of grey, only the dark blue can be obtained for slightly substochiometric WO 3 compound [2]. The pallet of colours exhibited by WO 3 coatings is due to interferometric effects. Recently, it was shown that playing with the gradient of the chemical composition of W-O layers it was possible to tune the global colour of the coatings, which made this system an attractive candidate for decorative applications [3].In this study the microstructural characterization of W-O coatings by transmission and scanning electron microsocopies (TEM and SEM, respectively) are presented. The coatings were deposited by reactive magnetron sputtering in RGPP mode (reactive gas pulsing process) [4]. SEM micrographs show the multilayer character of the deposited coatings whatever the pulsing parameters used in the deposition were (T -period, and t ON -injection time) [5].X-ray diffraction revealed that the structure of the coatings deposited by RGPP was in agreement to the multilayer effect, i.e. the detected phases were related to the W-rich and the O-rich layers forming the stacking [5]. All the coatings exhibited a mixture of α-W, β-W 3 O and quasi-crystalline W-O (a broad peak centred at 2θ ≈ 25 º, corresponding to the more intense peaks of WO 3 ) phases attributed to the W layer, a transition layer and the compound layer, respectively [5]. Using TEM, even in high-resolution mode, only 2 layers are possible to be distinguished (Fig. 1a), and the β-W 3 O phase could hardly be observed (see Fig. 1b), although electron diffraction (insert of Fig. 1a) confirmed its existence. The W-rich layer showed a fairly crystalline structure in comparison with the featureless aspect of the nanocrystalline O-rich layer.In order to distinguish and calculate the extension of each of the layers that form the stacking, the cross section of the coatings was analysed by energy filtering images (GIF) which allows evaluating the O concentration across the film thickness. The GIF images were obtained by subtraction of two images taken before and after the O-K edge defined at 530.6 eV, i.e. at -15 eV and +15 eV, respectively. Thus, the new image was generated by the electrons with energy between 515.6 and 545.6 eV as shown in Fig. 2a. By integration of the intensities in a selected area of Fig. 2a, the oxygen distribution across the coating thickness can be accessed (Fig. 2b). In this particular case, the definition of the stacking layers, including the transition layer, can be achieved, allowing to calculate their thickness, even i...

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Nanoscale colour control: W–O graded coatings deposited by magnetron sputtering

Cited by 4 publications

References 32 publications

Germanium-Based Optical Coatings for Aesthetic Enhancement with Low Radiofrequency Attenuation

Germanium-Based Optical Coatings for Aesthetic Enhancement with Low Radiofrequency Attenuation

Electron microscopy characterization of W-O multilayers

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