Chromaticity coordinate vector principle for charge-transfer-type thermochromic material design: case of Fe/Cr-(co)doped α-Al<sub>2</sub>O<sub>3</sub>host

Zhang, Wen; Xu, Hongwei; Wang, Shan; Fang, Hairui; Li, Tianyi; Zhang, Yumei; Li, Dongfei; Meng, Xiuxia; Hou, Changmin; Yuan, Long

doi:10.1039/d2tc02287g

Cited by 5 publications

(4 citation statements)

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“…Perovskite-structure oxides are a class of oxygen-defect-sensitive materials with many defect-related applications. ,, Among these, perovskite-structure stannates (ASnO 3±δ ) are one of the most important families of oxygen-defective materials with applications in oxygen ions and H + conductors. , The oxygen vacancy formation energy is low, which results in defects that can be tuned by ultraviolet light irradiation − and low oxidation states cation substitution of Sn 4+ . , In previous work, we have found the thermochromism of different chromophore groups in charge-transfer-type inorganic host follow a chromaticity vector principle . It is well-known that the electronic and optical behaviors of Sn-based oxide materials are sensitive to oxygen defects.…”

Section: Introductionmentioning

confidence: 99%

“…37,38 In previous work, we have found the thermochromism of different chromophore groups in charge-transfer-type inorganic host follow a chromaticity vector principle. 39 It is well-known that the electronic and optical behaviors of Snbased oxide materials are sensitive to oxygen defects. For example, the thermochromic property of β-Bi 2 Sn 2 O 7 shows calcination duration-dependent color evolution behavior.…”

Section: Introductionmentioning

confidence: 99%

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Thermally Induced Lattice-Defective Oxygen Breathing in Perovskite-Structure Stannates with High-Contrast Reversible Thermochromism

Zhang,

Wang,

Ivasishin

et al. 2024

ACS Appl. Mater. Interfaces

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Inorganic thermochromic materials exhibit a tunable color gamut and a wide chromatic temperature range, indicating their potential for intelligent adaptive applications in thermal warning, temperature indication, thermal regulation, and interactive light-to-thermal energy conversion. However, most metal-oxide-based thermochromic materials show weak chromaticity adaption with the change of temperature, which needs further understanding of the microscopic principle to clarify the potential route to improve the contrast and identifiability for fabricating better thermochromic materials. Using perovskitestructure (AMO 3 ) alkaline earth metal stannate (Ba 1−x Sr x SnO 3 , 0.0 ≤ x ≤ 1.0) as a model system, this paper reports for the first time the mechanism of the properties of thermally induced defect-enhanced charge transfer-type (CTT) thermochromic materials and the strategy for regulating their thermochromic properties by A-site cations. BaSnO 3 exhibits continuously reversible thermochromic properties with high contrast from weak light yellow (b* = 11) to strong bright yellow (b* = 58) between room temperature and 550 °C. In-situ high-temperature X-ray diffraction (in-situ XRD), in-situ UV−vis absorption spectroscopy (in-situ UV−vis), thermogravimetric (TG), and electron paramagnetic resonance (EPR) spectra indicate that this excellent thermochromic phenomenon is attributed to the weakening of Sn−O bond hybridization at high temperatures, as well as the formation of a large number of oxygen vacancies at the top of the valence band, and the enhanced charge transfer resulting from the generation of impurity levels in the Sn 2+ 5s 2 intermediate. Replacing Ba 2+ by Sr 2+ in Ba 1−x Sr x SnO 3 successfully tuned the thermochromic properties, which is attributed to the Sr 2+ doping level-directed oxygen defect concentration and deoxygenation rate. The demonstrated defect-enhanced charge transfer behavior promotes a feasible route for lattice oxygenmediated thermochromic materials and provides a fundamental relationship between thermally induced defects and colorimetry.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Thermally Induced Lattice-Defective Oxygen Breathing in Perovskite-Structure Stannates with High-Contrast Reversible Thermochromism

Zhang,

Wang,

Ivasishin

et al. 2024

ACS Appl. Mater. Interfaces

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“…However, all of the materials mentioned above have their limitations, vanadium oxide and molybdenum oxides mainly change color below 300 • C 21,22 ; rare-earth garnet structural oxide has good thermal stability but their visible spectra do not differ significantly at different temperatures, which indicates that the thermochromism is not significant 18,23 ; transition metal-doped oxide exhibit thermochromism at higher temperature (such as Y-doped Bi 2 O 3 20 at 20-777 • C, Co-doped ZnO 24 at 25-800 • C, and Co-doped TiO 2 25 at 20-800 • C), but their color-temperature correspondence has not been clearly explored. Recently, Yuan et al 26 have reported that the CIE-L × ab parameter can be described as a function of temperature for Fe/Cr-(co)doped α-Al 2 O 3 , but the function is close to a horizontal line and has a large error, which limits its further application. For this reason, it is urgently necessary to further investigate the high-temperature thermochromic mechanism and explore the color-temperature correspondence in the field of high-temperature thermochromic material for thermal indication.…”

Section: Introductionmentioning

confidence: 99%

Combined experimental and DFT study on high‐temperature thermochromism of Co‐doped LaCrO₃ coating for thermal indicator

Tong

Wang

et al. 2023

J Am Ceram Soc.

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Noncontact temperature measurement using thermochromic materials is vital in the field of temperature indication, but the related mechanisms behind thermochromic behavior are diverse and high complexity, and the color‐temperature correspondence is poorly explored. This paper systematically studied the thermochromic mechanisms and color‐temperature correspondence in the cobalt‐doped LaCrO3 coatings via experiment and density functional theory study. The coatings appear reversible thermochromism from green to black with temperature and composition, functions from room temperature to 700°C. This thermochromism is attributed to the lattice expansion and bandgap reduction as the temperature increase, and a model of temperature effect bandgap was proposed. Meanwhile, the coating temperature can be inferred from the color change because the CIE chromaticity coordinate of the coating varies linearly with temperature, and the mean relative error of thermochromic measurements is 8.28%. Furthermore, the cobalt doped introduces impurity energy levels and enhances the interaction between photons and carriers, which reduce the bandgap and increase the absorption in the visible spectrum resulting in darker colors. This work provides a stable and efficient high‐temperature thermochromic coating that has a wide thermochromic temperature range and clear color‐temperature correspondence, which shows broad application prospects in the field of thermal indication at high temperatures.

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“…Near-infrared light (700–1400 nm) is an electromagnetic wave that exists between visible and mid-infrared light and is greatly utilized in plant growth, night vision, medical imaging, food analysis, and so on. − In recent years, NIR pc-LED, which is recognized as a new generation of NIR light source, has garnered a lot of attention due to its high efficiency and compact size. − Cr 3+ is one of the most frequent activators of NIR phosphors. Its luminescence is greatly impacted by the crystal field with a narrow emission in a strong crystal field and a broadband one in a weak crystal field.…”

Section: Introductionmentioning

confidence: 99%

Spectral Broadening in Cr³⁺-Doped Sr_0.92Mg_0.91Al_10.1O₁₇ NIR Phosphor Realized by Multi-crystallographic Site Occupation

Zheng

Kuang

Shen

et al. 2023

ACS Appl. Opt. Mater.

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Near-infrared phosphor-converted light-emitting diodes (NIR pc-LEDs) play an important role in nondestructive testing, medical imaging, food analysis, and so on. Broadband NIR phosphors are needed in order to cover the characteristic wavelengths of various matters. In this paper, a NIR phosphor, Sr 0.92 Mg 0.91 Al 10.1 O 17 (SMAO):Cr 3+ , with a full width at half maximum (FWHM) of 12−102 nm is achieved as a function of Cr 3+ concentration. Two Cr 3+ sites are observed by means of excitation spectra and fluorescence decay curves. The spectral broadening with the increase of Cr 3+ concentration is attributed to the increase of occupation ratio on the weak crystal field site by Cr 3+ . In addition, the difference in thermal stability between 2 E and 4 T 2 is employed to conduct the temperature measurement with a relative sensitivity of 0.43% K −1 at 270 K. A NIR pc-LED is fabricated using SMAO:0.03Cr 3+ phosphor combined with a 395 nm LED chip with radiation flux of 2.2 mW@10 mA and 15 mW@100 mA.

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Chromaticity coordinate vector principle for charge-transfer-type thermochromic material design: case of Fe/Cr-(co)doped α-Al₂O₃host

Abstract: Charge-transfer-type thermochromic materials gain increasing research interest due to its smart character of reversibly continuous color-change presenting with temperature. However, the interaction between different chromophore in the same host matrix...

Cited by 5 publications

References 81 publications

Thermally Induced Lattice-Defective Oxygen Breathing in Perovskite-Structure Stannates with High-Contrast Reversible Thermochromism

Thermally Induced Lattice-Defective Oxygen Breathing in Perovskite-Structure Stannates with High-Contrast Reversible Thermochromism

Combined experimental and DFT study on high‐temperature thermochromism of Co‐doped LaCrO₃ coating for thermal indicator

Spectral Broadening in Cr³⁺-Doped Sr_0.92Mg_0.91Al_10.1O₁₇ NIR Phosphor Realized by Multi-crystallographic Site Occupation

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Chromaticity coordinate vector principle for charge-transfer-type thermochromic material design: case of Fe/Cr-(co)doped α-Al2O3host

Abstract: Charge-transfer-type thermochromic materials gain increasing research interest due to its smart character of reversibly continuous color-change presenting with temperature. However, the interaction between different chromophore in the same host matrix...

Cited by 5 publications

References 81 publications

Thermally Induced Lattice-Defective Oxygen Breathing in Perovskite-Structure Stannates with High-Contrast Reversible Thermochromism

Thermally Induced Lattice-Defective Oxygen Breathing in Perovskite-Structure Stannates with High-Contrast Reversible Thermochromism

Combined experimental and DFT study on high‐temperature thermochromism of Co‐doped LaCrO3 coating for thermal indicator

Spectral Broadening in Cr3+-Doped Sr0.92Mg0.91Al10.1O17 NIR Phosphor Realized by Multi-crystallographic Site Occupation

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Product

Resources

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Chromaticity coordinate vector principle for charge-transfer-type thermochromic material design: case of Fe/Cr-(co)doped α-Al₂O₃host

Combined experimental and DFT study on high‐temperature thermochromism of Co‐doped LaCrO₃ coating for thermal indicator

Spectral Broadening in Cr³⁺-Doped Sr_0.92Mg_0.91Al_10.1O₁₇ NIR Phosphor Realized by Multi-crystallographic Site Occupation