Study the effect of alkali/alkaline earth addition on the environment of borochromate glasses by means of spectroscopic analysis

Ahmad, F.

doi:10.1016/j.jallcom.2013.10.105

Cited by 78 publications

(20 citation statements)

References 44 publications

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“…This finding allows us to revisit some earlier studies where the optical band gap of Cr-doped ZnO and TiO2 was largely underestimated [33][34][35]54,55] . In fact, similar ambiguous determination of the optical band gap for other systems doped with Cr, such as borate glasses, is often found in literature [41,42] . In Fig.…”

Section: Resultssupporting

confidence: 69%

“…Similar gap size discrepancies can be found in other gapped systems, such as glasses, when doped with TMs. The band gap in Cr-doped borate glasses, for example, was reported to be ~1.3 eV smaller than the typical value for borate glasses [41,42] , while recent studies claim barely affected (± 0.2 eV) band gap due doping [43,44] . In fact, on theoretical bases, one should not expect large band structure variations (except for energy shifts) or gap size modulation for doping level as diluted as dopants per more than six-unit cells [45,46] .…”

Section: Introductionmentioning

confidence: 86%

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Precise determination of optical band gap in Cr-doped semiconductor nanowires

et al. 2022

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Pristine and chromium-doped ZnO nanowires were prepared following the traditional coprecipitation method. X-ray diffraction data identified a pure wurtzite hexagonal crystal structure characteristic for ZnO, irrespective of the doping level. The particle size, as deduced form Williamson-Hall plots, was found to be 45-55 nm for all samples. Scanning electron microscopy revealed a clear nanowires morphology for the pure and doped samples, while elemental analysis ensured the successful Cr-doping. Distinct spectroscopic signatures of Cr-doping were revealed from a detailed deconvolution process applied to optical spectra of doped samples, where Cr 3+ optical transitions were unambiguously identified at ~420 and ~665 nm. Particularly relevant, is the spectral decomposition here performed for the superimposed absorption edge (~385 nm) and Cr 3+ optical resonance at ~420 nm, allowing to claim practically doping-independent optical band gap behavior in the present doping regime. This is further supported by identifying the characteristic ZnO near edge photoluminescence peak (~ 392 nm) which maintains fixed wavelength after Crdoping. These findings contrast earlier studies on Cr-doped semiconductor nanoparticles and glass systems where the optical band gap has been largely underestimated. We attribute the inconsistence band gap values reported in literature for Cr-doped semiconductors to the proximity of Cr optical transitions to the semiconductor absorption edge.

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Section: Resultssupporting

confidence: 69%

Section: Introductionmentioning

confidence: 86%

Precise determination of optical band gap in Cr-doped semiconductor nanowires

et al. 2022

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“…In particular, for the maximum doping level here used (i.e., sample with x = 0.5), the apparent absorption edge could mislead the estimation of the band gap to be ~ 2.6 eV. Notice that a ~ 1 eV change in the band edge for such a tinny Cr-doping (x = 0.5) is unpredictable, although earlier borate-related literature reported underestimated energy gaps within the range 2-2.5 eV [16][17][18][19][20][21][22][23]. In fact, such large underestimation of band edge position and gap size is also found for other glassy systems [24][25][26][27][28] and TM-doped semiconductor nano materials [29][30][31][32].…”

Section: Optical Absorption Resultsmentioning

confidence: 86%

Optical transitions from hexavalent chromium in lithium-borate glasses

et al. 2021

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The melt-quenching technique was used to prepare a series of chromium-doped borate glasses with the composition xCr2O3 -(70-x) B2O3-30 Li2O-(x = 0, 0.1, 0.2, 0.3 and 0.5 mol %). The low-doping level here employed allowed to unambiguously identify welldefined near-edge Cr 6+ optical transitions, and to precisely determine the optical band gap of the borate glass host. Additional Cr 3+ transitions were observed in the visible regime, rendering a strong modulation of the glass color, from colorless to dark greenish, with Cr content. Both Cr 6+ (after the charge transfer transformation into Cr 5+ ) and Cr 3+ oxidation states and their variations with Cr doping were identified from electron spin resonance spectroscopy. All samples exhibit similar vibrational spectra dominated by BO3 and BO4 structural units, with the development of weak Cr 6+ vibration with Cr doping. The present study provides structurally similar but optically active and tunable glass hosts suitable for various optical applications.

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“…The complete absence of any sharp peak indicates their amorphous nature. Moreover, the patterns exhibit a broad hump at (2θ~ 30 o ), which is a typical feature of borate glass [26].…”

Section: X-ray Diffractionmentioning

confidence: 95%

The effect of Alkali Type on the Optical Behavior of Cu Doped Borate Glass Bandpass Filter

2017

Egyptian Journal of Solids

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Borate oxide glass system of composition: 30Y 2 O-43B 2 O 3-7CuO-20ZnO where (Y= Li, Na and K) were prepared using the melt-quenching technique. Some physical properties were studied; such as X-ray diffraction, density, UV-Visible transmission spectra, ESR and FTIR. The density was measured by Archimedes method and the molar volume was calculated. It is found that density and the molar volume show opposite trend. The optical transmission was measured in the spectral range of 200-1100 nm. Some optical properties were determined. The characterized parameters of these filters, i. e. area, center, width, height and full wave at half maximum (FWHM) of band pass, have been estimated. These parameters have been found to be dependent on the alkali type. FTIR spectral studies indicate the presence of triangular and tetrahedral borate structural units. The absorption band observed in the wavelength region 550 nm in these glasses and is the characteristic of Cu 2+ ions. ESR studies suggest that Cu 2+ ions inter into the lattice as copper divalent state.

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Study the effect of alkali/alkaline earth addition on the environment of borochromate glasses by means of spectroscopic analysis

Cited by 78 publications

References 44 publications

Precise determination of optical band gap in Cr-doped semiconductor nanowires

Precise determination of optical band gap in Cr-doped semiconductor nanowires

Optical transitions from hexavalent chromium in lithium-borate glasses

The effect of Alkali Type on the Optical Behavior of Cu Doped Borate Glass Bandpass Filter

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