Phase evolution and optical properties of nanometric Mn-doped TiO2 pigments

Dias, Jeferson Almeida; Freire, Ana L.F.; Girotto, Isabelly; Roveri, Carolina Del; Mastelaro, Valmor Roberto; Paris, Elaine Cristina; Giraldi, Tania R.

doi:10.1016/j.mtcomm.2021.102295

Cited by 7 publications

(8 citation statements)

References 74 publications

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“…F(r) is calculated by the Kubelka–Munk formula: F(r) = (1 − R) 2 /2R, and (F(r)*E) 2 is used as the vertical coordinate. The graph is extrapolated as a tangent, and the intercept of the tangent on the horizontal axis is the bandgap (E g ) [ 21 , 33 , 34 ]. The colorimetric parameters of the pigments and colored glaze in the CIELab system were measured using an Automatic Whiteness meter (WSD-3C, Beijing, China), in which L* is the Lightness axis (black (0)/white (100)), a* is the green (−)/red (+) axis and b* is the blue (−)/yellow (+) axis.…”

Section: Methodsmentioning

confidence: 99%

“…Therefore, the elemental doping modification strategy was applied to adjust the bandgap and spectral properties of rutile TiO 2 for developing pigments with different colors [ 17 , 18 , 19 ]. Currently, several elements as chromophore ions with valence states below 4+ such as Cr, Ni, Mn, Fe, Co or V were doped into the rutile lattice to substitute for Ti 4+ , obtaining pigments with different colors from orange to yellow to brown to gray, and even to green [ 20 , 21 , 22 ]. In order to balance the charge difference between the chromophore (such as Cr 3+ ) and Ti 4+ , a second ion with higher valence states (so-called counterion, e.g., Sb, Nb, W and Mo) needs to be introduced to achieve the desired chromatic properties [ 19 , 23 , 24 ].…”

Section: Introductionmentioning

confidence: 99%

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Insight into the Effect of Counterions on the Chromatic Properties of Cr-Doped Rutile TiO2-Based Pigments

Zhou

Zhang

Chen³

et al. 2022

Materials

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Rutile TiO2 pigments codoped with chromophore ion Cr3+ and various charge-balancing ions (i.e., counterions species of Sb, Nb, W and Mo) were prepared by a solid-phase reaction method. The effects of the counterions and calcination temperatures on the phase structure, color-rendering and spectroscopic properties, microstructure, and stability of the synthesized pigments were investigated in detail. The results showed that the introduction of 5–10% counterions improved the solubility of Cr3+ in the TiO2 lattice to form the single-phase rutile pigments calcined at 1100 °C for 2 h. The 10% Cr-doped pigment showed a dark brown color. Depending on the content and type of counterions, the color of the codoped pigments was tailored from yellow to reddish or yellowish-orange to black with different brightness and hue. The influence mechanism of counterions was ascribed to the lattice distortion and variation in the charge balance condition. It was found that the addition of Sb, Nb, or Mo resulted in a remarkable improvement in the NIR reflectance of pigments. The grain growth was inhibited with the codoping of Cr/Sb and Cr/Nb to achieve the nano-sized pigments. In addition, the prepared pigments exhibited good acid and alkali corrosion resistance as well as excellent stability and coloring performance in transparent ceramic glazes.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Insight into the Effect of Counterions on the Chromatic Properties of Cr-Doped Rutile TiO2-Based Pigments

Zhou

Zhang

Chen³

et al. 2022

Materials

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“…Mg-doping of TiO 2 can passivate an electron trap, thus providing superior interfacial charge transport . However, Mn-doped TiO 2 was found susceptible to phase segregation (between Mn 3+ and TiO 2 ) as Mn 2 O 3 and instability at a high calcination temperature (800 °C) . In order to enhance the visible-light reactivity, TiO 2 has been doped with Cr 3+ to modify its electronic band structure .…”

Section: Doping Of Tio2mentioning

confidence: 99%

Mechanistic Understanding in Manipulating Energetics of TiO₂ for Photocatalysis

2023

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Titanium dioxide (TiO2) is a wide bandgap semiconductor that has a wide range of applications including wastewater treatment, photocatalysis, solar cells, and sensors owing to its excellent electronic and optical properties. However, the wide bandgap of TiO2 (∼3.2 eV) along with the recombination processes of the photoexcited charge carriers reduce its interfacial charge transport properties and respective activities. Energetics, optical response, and corresponding photophysics of excited charge carriers can be altered through doping and codoping of TiO2 and composite formulation. Therefore, it is very crucial to understand the structure–property and property-application relationships of doped, co-doped, and composite TiO2 to maximize the efficiency and extend the fundamental understanding for their applications in different fields. In this Perspective, we summarize the ongoing research on the advancement of undoped, doped, co-doped, and composite TiO2 including their structure and morphology, energetics, and corresponding photophysics relative to their applications in photocatalysis, wastewater treatment, and water-splitting reactions. We then propose our perspectives on the future potential of energetic manipulation of photocatalytic TiO2 to develop advanced and highly efficacious catalytic materials.

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“…The UV band at 245 nm was ascribed to the intrinsic band-gap absorption of titanate matrix, i.e. electronic transition from the valence band (VB) to conduction band (CB) [34,39,40]. Mn-doped TiO 2 matrices with x= 0.005 and 0.01 showed additional visible band centered at 415 nm, and the absorption edge was shifted to about 480-500 nm.…”

Section: Optical Propertiesmentioning

confidence: 99%

“…The trapped electrons in V O generate donor states near the VB. Increase of V O concentration gives rise to a positive correction of the VB edge which, consequently, results in shrinkage of the band gap [34,46]. Moreover, in Mndoped titania, Ti-O-Mn bonds could also be formed generating another type of defect sites which create more energy states within the band gap and, thus, contributing to the band gap narrowing too [45].…”

Section: Optical Propertiesmentioning

confidence: 99%

Sol‒gel synthesis, structure, ferromagnetism and optical properties of Mn‒doped titania diluted magnetic semiconductors nanoparticles

2022

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Diluted magnetic semiconductors composed of Ti 1-x Mn x O 2 nanoparticles, where x ranges from 0.0 to 0.1, were synthesized utilizing the sol-gel processing. X-ray diffraction (XRD), high resolution transmission electron microscopy, ultravioletvisible (UV-Vis) diffuse reflectance spectroscopy (DRS) and vibrating sample magnetometry (VSM) were used for structural, optical and magnetic characterization of the prepared nanomaterials. XRD revealed the coexistence of nanosized anatase and rutile phases with no secondary phase up to x= 0.07. When x= 0.1, a minority of secondary Mn 2 O 3 phase was detected. It was also found that increasing x, i.e. increase of Mn content, increased the anatase content at the expense of rutile, increased the cell parameters of both of anatase and rutile, and decreased the average crystallite nanosize of both of them. UV-Vis DRS absorption spectra exhibited peaks around 415-435 and 515 nm which corresponded to Mn 2+ and Mn 3+ ions, respectively. The band gap (E opt ) values suggest the semiconducting behavior for all the investigated compositions. E opt significantly decreased with increasing Mn concentration. VSM results indicated that pure titania is diamagnetic. While, all the studied Mn-doped TiO 2 compositions exhibited room temperature ferromagnetism. However, weaker ferromagnetism, shown by increased unsaturation, was observed with increasing Mn content.

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Phase evolution and optical properties of nanometric Mn-doped TiO2 pigments

Cited by 7 publications

References 74 publications

Insight into the Effect of Counterions on the Chromatic Properties of Cr-Doped Rutile TiO2-Based Pigments

Insight into the Effect of Counterions on the Chromatic Properties of Cr-Doped Rutile TiO2-Based Pigments

Mechanistic Understanding in Manipulating Energetics of TiO₂ for Photocatalysis

Sol‒gel synthesis, structure, ferromagnetism and optical properties of Mn‒doped titania diluted magnetic semiconductors nanoparticles

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Phase evolution and optical properties of nanometric Mn-doped TiO2 pigments

Cited by 7 publications

References 74 publications

Insight into the Effect of Counterions on the Chromatic Properties of Cr-Doped Rutile TiO2-Based Pigments

Insight into the Effect of Counterions on the Chromatic Properties of Cr-Doped Rutile TiO2-Based Pigments

Mechanistic Understanding in Manipulating Energetics of TiO2 for Photocatalysis

Sol‒gel synthesis, structure, ferromagnetism and optical properties of Mn‒doped titania diluted magnetic semiconductors nanoparticles

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Mechanistic Understanding in Manipulating Energetics of TiO₂ for Photocatalysis