Spectroscopic assignments of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mtext>Ti</mml:mtext></mml:mrow><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mtext>Ti</mml:mtext></mml:mrow><mml:mrow><mml:mn>4</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>in titanium-doped<mm

Andrade, L.H.C.; Lima, S.M.; Novatski, Andressa; Neto, A. M. J. C.; Bento, A. C.; Baesso, Mauro Luciano; Gandra, F. C. G.; Guyot, Y.; Boulon, G.

doi:10.1103/physrevb.78.224202

Cited by 33 publications

(16 citation statements)

References 47 publications

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“…When quenched in air, the as‐prepared glass samples appeared honey‐brown in color. This brownish color normally is associated with the presence of Ti 3+ ions in the glass structure according to . Their concentration can be sufficiently reduced by further thermal annealing (usually performed to relieve the residual stresses after quenching) and conversion into Ti 4+ , which can account for the changes in the color of the annealed glass samples toward more dark .…”

Section: Resultsmentioning

confidence: 99%

Nature of Pd and Ti Metals in the Structure of CMAS Glass and Ceramics

Golovchak

Davis²,

Vullo³

et al. 2014

J. Am. Ceram. Soc.

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The structure of electrically conductive CMAS‐TiO2‐Pd glass and ceramics was investigated by transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), X‐ray photoelectron spectroscopy (XPS), X‐ray absorption near‐edge spectroscopy (XANES), and extended X‐ray absorption fine structure spectroscopy (EXAFS). The XANES spectra of Ti do not show any significant difference between the glasses ceramized in air or in a reducing “forming” gas, as well as between Pd‐containing versus Pd‐free samples, nor between surface versus bulk of the glass‐ceramic samples. However, EXAFS and XANES data recorded at the Pd K‐edge show significant dependences on whether the glass‐ceramic was ceramized in air or in “forming” gas. The XPS spectra of Ti 2p core‐level electrons for glasses ceramized in air or “forming” gas also show a strong difference depending on whether the samples did or did not contain Pd. STEM mapping confirms the existence of grains in the form of main crystalline phases identified with XRD, and also reveals the existence of Pd nanoparticles in glasses ceramized in both air and in “forming” gas.

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Section: Resultsmentioning

confidence: 99%

Nature of Pd and Ti Metals in the Structure of CMAS Glass and Ceramics

Golovchak

Davis²,

Vullo³

et al. 2014

J. Am. Ceram. Soc.

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“…Moreover, the luminescence of Ti 3? has been reported in matrices as aluminosilicate glass [31,32] and bazirite-type BaZr 1-xTi x Si 3 O 9 phosphors [33]. The UV-excited emission spectra of the representative ZrO 2 materials (W: 3) annealed at 800 and 1000°C differ significantly from that of the material annealed at 600°C (Fig.…”

Section: Structural Dependence Of Zro 2 Photoluminescencementioning

confidence: 87%

Structure–property relationship of luminescent zirconia nanomaterials obtained by sol–gel method

et al. 2014

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Nanocrystalline ZrO 2 materials were prepared by sol-gel method combining different W = [H 2 O]/[ZTB] ratios (ZTB: zirconium tetrabutoxide) with 600, 800, and 1000°C annealing temperatures, yielding diverse phase compositions. A lower post-synthesis annealing temperature (600°C) favored the t-ZrO 2 tetragonal phase while higher temperatures (800 and 1000°C) yielded the monoclinic one (m-ZrO 2 ). Depending on the preparation conditions, mixed structure materials are readily obtained. The luminescence activator in the undoped ZrO 2 is assumed as trivalent titanium and emission bands are assigned to the 3d 1 (e g ) ? 3d 1 (t 2g ) transition. Due to weaker crystal field in m-ZrO 2 form, the Ti 3? emission band is red-shifted from 410 nm in t-ZrO 2 to 500 nm. The luminescence intensity of the t-ZrO 2 form is quenched at higher temperature than that of m-ZrO 2 , indicating higher activation energy and smaller Stokes shift. The undoped ZrO 2 excitation seems to involve photoionization of Ti 3? to Ti IV . Simultaneously, the freed electron is trapped to the oxygen vacancies (F ?? centers) created by Ti 3? /Ti IV charge compensation, so this can be considered as a metalto-host/ligand charge transfer. Since most of the excitation results in immediate emission, the traps are probably very shallow though deeper ones leads to the persistent luminescence from the undoped ZrO 2 .

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“…300 nm are related to the e − (O 2− (2p))→Ti IV charge transfer, which can occur through two possible molecular transitions: t 1u (π b )→t 2g (π*) or t 2u (π)→t 2g (π*), being typically observed at ca. 280 nm [23,24,42,48,59]. Lastly, the energy gaps between the valence and the conduction bands are identified at ca.…”

Section: Appl Sci 2017 7 1243mentioning

confidence: 90%

Section: Luminescence Propertiesmentioning

confidence: 97%

“…However, the shift may indicate either that the activator center is occupying multiple sites with different crystal field strengths in the host lattice, or the presence of defects in the structure of the X-Hec materials. The multisite origin for emission is also witnessed in the decrease of emission band width [42] with increasing excitation wavelength. Similar blue-green emission has previously been observed for other silicates such as fluorohectorite [23], chlorohectorite [24], montmorillonite [43], kaolinite [44], pyrophyllite [45], topaz (Al2SiO4(F,OH)2) [46], synthetic hackmanite (Na8Al6Si6O24(Cl,S)2) [47,48], benitoite (BaTiSi3O9) [49], and SiO2 [50,51].…”

Section: Appl Sci 2017 7 1243mentioning

confidence: 97%

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Synthesis and Features of Luminescent Bromo- and Iodohectorite Nanoclay Materials

et al. 2017

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Abstract:The smectites represent a versatile class of clay minerals with broad usage in industrial applications, e.g., cosmetics, drug delivery, bioimaging, etc. Synthetic hectorite Na 0.7 (Mg 5.5 Li 0.3 ) [Si 8 O 20 ](OH) 4 is a distinct material from this class due to its low-cost production method that allows to design its structure to match better the applications. In the current work, we have synthesized for the first time ever nanoclay materials based on the hectorite structure but with the hydroxyl groups (OH − ) replaced by Br − or I − , yielding bromohectorite (Br-Hec) and iodohectorite (I-Hec). It was aimed that these materials would be used as phosphors. Thus, OH − replacement was done to avoid luminescence quenching by multiphonon de-excitation. The crystal structure is similar to nanocrystalline fluorohectorite, having the d 001 spacing of 14.30 Å and 3 nm crystallite size along the 00l direction. The synthetic materials studied here show strong potential to act as host lattices for optically active species, possessing mesoporous structure with high specific surface area (385 and 363 m 2 g −1 for Br-Hec and I-Hec, respectively) and good thermal stability up to 800 • C. Both materials also present strong blue-green emission under UV radiation and short persistent luminescence (ca. 5 s). The luminescence features are attributed to Ti 3+ /Ti IV impurities acting as the emitting center in these materials.

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Spectroscopic assignments ofTi3+andTi4+in titanium-doped

Cited by 33 publications

References 47 publications

Nature of Pd and Ti Metals in the Structure of CMAS Glass and Ceramics

Nature of Pd and Ti Metals in the Structure of CMAS Glass and Ceramics

Structure–property relationship of luminescent zirconia nanomaterials obtained by sol–gel method

Synthesis and Features of Luminescent Bromo- and Iodohectorite Nanoclay Materials

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