Thermochromic sputter-deposited vanadium oxyfluoride coatings with low luminous absorptance

Khan, K. A.; Granqvist, Claes‐Göran

doi:10.1063/1.102388

Cited by 78 publications

(26 citation statements)

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“…13 The luminous transmittance can be boosted by magnesium substitution [14][15] and by fluorination. 16 The metal-insulator transition can be influenced by a variety of external parameters, and recent work have considered the effects of strain [17][18][19] and lattice misfit with the substrate, 20,21 electric field or current activation, [22][23][24][25][26][27][28][29][30][31] light irradiation, [32][33][34][35][36][37][38] ion bombardment, 39,40 and gaseous ambience. 41 Considering the wealth of possibilities to modulate the properties of VO 2 -based thin films, it is not surprising that they are discussed for a vast number of applications such as thermochromic "smart" windows for energy efficient buildings, [42][43][44][45][46][47][48][49][50] variable-thermal-emittance surfaces for thermal radiation control, 51 oscillators and switches in (opto)electronics, 25,26,34,52,53 transistors of different types, <...>…”

Section: Introductionmentioning

confidence: 99%

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

Namura

Suzuki

et al. 2013

Journal of Applied Physics

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Thermochromic VO 2 nanorods made by sputter deposition: Growth conditions and optical modeling. Reactive dc magnetron sputtering onto glass-based substrates yielded deposits of thermochromic VO 2 with well-developed nanorods and nanowires. Their formation was promoted by high substrate temperature (above ~500 °C), sufficient film thickness, proper inlet of the reactive gas, dispersed gold "seeds" and pronounced substrate roughness. Rutherford back scattering ascertained mass thicknesses, scanning electron microscopy depicted the nanostructures, and glancing incidence Xray diffraction proved that single-phase VO 2 was normally formed. Journal of Applied PhysicsSpectrophotometric measurements of total and diffuse transmittance and reflectance on VO 2 thin films, at room temperature and ~100 °C, allowed us to determine complex dielectric functions below and above the "critical" temperature for thermochromic switching (~68 °C). These data were then used in computations based on the Bruggeman effective medium theory applied to randomly oriented prolate spheroidal structural units to derive the optical properties of the deposits.Experimental and computed data on spectral absorptance were found to be in good qualitative agreement.

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Section: Introductionmentioning

confidence: 99%

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

Namura

Suzuki

et al. 2013

Journal of Applied Physics

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“…10 Fluorine doping is another way to enhance T lum . [26][27][28][29] Furthermore, antireflection (AR) coatings are able to improve T lum and ΔT sol , and especially good properties have been reported for five-layer coatings of alternating TiO 2 and VO 2 . 2,3 Recent modeling studies on "nanothermochromics" 4,5 have shown that VO 2 nanoparticles can offer significantly higher values of T lum and ΔT sol than films, and these new possibilities have led to a burst of research on such nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Thermochromic undoped and Mg-doped VO₂ thin films and nanoparticles: Optical properties and performance limits for energy efficient windows

Niklasson

Granqvist

2014

Journal of Applied Physics

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Undoped and Mg-doped thermochromic VO 2 films with atom ratios z ≡ Mg/(Mg + V) of 0 ≤ z < 0.21 were deposited by reactive DC magnetron sputtering onto heated glass and carbon substrates. Elemental compositions were found by Rutherford backscattering spectrometry. Optical constants were determined from transmittance and reflectance measurements and were used for modeling the optical properties of thin films and dilute nanoparticle composite layers below and above the critical temperature for thermochromic switching between a low-temperature infrared transparent state and a high-temperature infrared reflecting or absorbing state. Mgdoped films showed superior luminous transmittance T lum and solar transmittance modulation ΔT sol compared to undoped VO 2 films, and both of these parameters could be further enhanced by anti-reflection. VO 2 -containing nanocomposites had much larger values of T lum and ΔT sol than VO 2 -based films. Mg-doping was found to erode the properties of the nanocomposites. Approximate performance limits are given on T lum and ΔT sol for thermochromic VO 2 films, with and without Mg doping and antireflection coating, and also for VO 2 -containing dilute nanocomposites.--

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“…Figure 11 indicates that T lum is increased from 39% to 51% as the amount of Mg goes from zero to 7.2%. Band-gap widening can be accomplished also by adding other alkaline earth metals [83], zinc [88] or terbium [89], or by replacing some of the oxygen with fluorine [90][91][92]. zero to 7.2%.…”

Section: Towards Vo2-based Thin Films For Glazingsmentioning

confidence: 99%

Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings

Granqvist

Niklasson

2016

Buildings

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Today's advances in materials science and technology can lead to better buildings with improved energy efficiency and indoor conditions. Particular attention should be directed towards windows and glass facades-jointly known as "glazings"-since current practices often lead to huge energy expenditures related to excessive inflow or outflow of energy which need to be balanced by energy-intensive cooling or heating. This review article outlines recent progress in thermochromics, i.e., it deals with materials whose optical properties are strongly dependent on temperature. In particular, we discuss oxide-based thin surface coatings (thin films) and nanoparticle composites which can be deposited onto glass and are able to regulate the throughput of solar energy while the luminous (visible) properties remain more or less unaltered. Another implementation embodies lamination materials incorporating thermochromic (TC) nanoparticles. The thin films and nanocomposites are based on vanadium dioxide (VO 2 ), which is able to change its properties within a narrow temperature range in the vicinity of room temperature and either reflects or absorbs infrared light at elevated temperatures, whereas the reflectance or absorptance is much smaller at lower temperatures. The review outlines the state of the art for these thin films and nanocomposites with particular attention to recent developments that have taken place in laboratories worldwide. Specifically, we first set the scene by discussing environmental challenges and their relationship with TC glazings. Then enters VO 2 and we present its key properties in thin-film form and as nanoparticles. The next part of the article gives perspectives on the manufacturing of these films and particles. We point out that the properties of pure VO 2 may not be fully adequate for buildings and we elaborate how additives, antireflection layers, nanostructuring and protective over-coatings can be employed to yield improved performance and durability that make TC glazings of considerable interest for building-related applications. Finally, we briefly describe recent developments towards TC light scattering and draw some final conclusions.

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Thermochromic sputter-deposited vanadium oxyfluoride coatings with low luminous absorptance

Cited by 78 publications

References 10 publications

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

Thermochromic undoped and Mg-doped VO₂ thin films and nanoparticles: Optical properties and performance limits for energy efficient windows

Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings

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Thermochromic sputter-deposited vanadium oxyfluoride coatings with low luminous absorptance

Cited by 78 publications

References 10 publications

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

Thermochromic VO2 nanorods made by sputter deposition: Growth conditions and optical modeling

Thermochromic undoped and Mg-doped VO2 thin films and nanoparticles: Optical properties and performance limits for energy efficient windows

Thermochromic Oxide-Based Thin Films and Nanoparticle Composites for Energy-Efficient Glazings

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Thermochromic undoped and Mg-doped VO₂ thin films and nanoparticles: Optical properties and performance limits for energy efficient windows