Color centers in topaz: comparison between neutron and gamma irradiation

Ribeiro, Ludmila Mendonça Lopes; Pinheiro, M. V. B.; Leal, Alexandre Soares; Menezes, Maria Ângela de B. C.; Spaeth, J.‐M.

doi:10.1007/s00269-007-0160-z

Cited by 23 publications

(13 citation statements)

References 11 publications

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“…Calculations for silanone by TD-DFT with exchange correlation functional (B3LYP/6-31+G * ) give transitions comparable with these lines [32]. A line at 16000 cm −1 in blue topaz was attributed by Krambrock et al [24], considering the phenomenological theory of small bound polarons, to the fact that an O − hole center nearest to an acceptor defect is stabilized by lattice distortions.…”

Section: Spectral Decomposition Analysismentioning

confidence: 56%

“…Discussions, taking into account highly accurate quantum mechanical calculations [31,32] and results in spodumene [15] and beryl [10], led to assigning the lines at 41630 and 38510 cm −1 to a silicon dangling bond defect (=Si:) and the line at 60900 cm −1 to an oxygen vacancy defect (≡Si-Si≡). The decomposition of the spectra of thin and thick samples submitted to heat treatment at 200 • C shows a line at around 16000 cm −1 due to an O − hole center nearest to an acceptor defect being stabilized by lattice distortions [24]. Furthermore, two lines around 32000 and 42000 cm −1 , based on similar lines observed in spodumene, suggested for assignment a single defect such as silanone (=Si=O).…”

Section: Resultsmentioning

confidence: 74%

“…Further, Schirmer developed a model of O − hole centers in oxide materials, that is, a hole is trapped in a cluster of a few several equivalent oxygen ions next to an acceptor defect and is stabilized by lattice distortion as an O − bound small polaron [23]. Accordingly, Krambrock et al discussed the 620 nm absorption band and O − hole centers in the context of O − bound small polarons [24].…”

Section: Advances In Condensed Matter Physicsmentioning

confidence: 99%

“…Gemological quality crystals of beryl, quartz, spodumene, topaz, and tourmaline among many others, constitute an important economic resource for the Eastern Brazilian Pegmatite Province [4]. The optical absorption spectra of crystals of the Province of Oriental Brazilian Pegmatite were reported by several authors for beryl [5][6][7][8][9][10], amethyst [11], spodumene [12][13][14][15], topaz [16][17][18][19][20][21][22][23][24], and tourmaline [25].…”

Section: Introductionmentioning

confidence: 99%

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Color Dependence on Thickness in Topaz Crystal from Brazil

Bonventi

Isotani

Albuquerque

2012

Advances in Condensed Matter Physics

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It is well known that crystals of topaz from the Eastern Brazilian Pegmatite Province may turn blue by the irradiation with 60 Co gamma rays followed by heat treatment. Also, it is known that the sensation of color changes with the thickness of these crystals. The dependence of the color, given by 1931 CIE chromaticity coordinates, with the thickness of the crystal was analyzed. The absorbance used in the calculation of these coordinates was given by the sum of Gaussian lines. The parameters of these lines were determined through the decomposition of the optical absorption spectra in the ultraviolet and visible regions. The decomposition revealed several lines, whose assignment was made considering studies in spodumene and beryl crystals and highly accurate quantum mechanical calculations. The transmittance becomes very narrow with increasing thickness, and the CIE chromaticity coordinates converge to the borderline of the CIE Chromaticity Diagram at the wavelength of maximum transmittance. Furthermore, the purity of color increases with increasing thickness, and the dominant wavelength reaches the wavelength of maximum transmittance.

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Section: Spectral Decomposition Analysismentioning

confidence: 56%

Section: Resultsmentioning

confidence: 74%

Section: Advances In Condensed Matter Physicsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Color Dependence on Thickness in Topaz Crystal from Brazil

Bonventi

Isotani

Albuquerque

2012

Advances in Condensed Matter Physics

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“…They found that Cr 3+ plays a key role as a CL color center not only in yellow but also red luminescing topaz. Neutron and gamma-ray irradiation are known to modify color centers of topaz enhancing the blue color (da Silva et al, 2005;Krambrock et al, 2007;Zhang et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Relation between cathodoluminescence and trace-element distribution of magmatic topaz from the Ary-Bulak massif, Russia

et al. 2016

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In order to define the cathodoluminescence (CL) properties of magmatic topaz and its relation with trace-element composition, we studied topaz phenocrysts from the Ary-Bulak ongonite massif, Russia using a wide array of analytical techniques. Scanning electron microscopy CL panchromatic images reveal strong variations, which define micrometre-scale euhedral growth textures. Several truncations of these growth textures occur in single grains implying multiple growth and resorption events. The CL-spectra of both CLbright and -dark domains have a major peak in the near-ultraviolet centred at 393 nm. Cathodoluminescence images taken after several minutes of electron bombardment show decreasing emission intensity. Electron microprobe analyses indicate high F concentrations (average OH/(OH + F) = 0.04 calculated by difference, 100 wt.% – total from electron probe microanalyses), consistent with what has been found previously in topaz-bearing granites, and the OH stretching vibration (∼3653 cm–1) was detected in Raman spectra. Laser ablation inductively-coupled plasma mass spectrometry traverses performed across the CL textures detected trace elements at ppm to thousands of ppm levels, including: Fe, Mn, Li, Be, B, P, Nb, Ta, W, Ti, Ga, light rare-earth elements, Th and U. Lithium, W, Nb and Ta appear to be correlated with CL intensity, suggesting a role for some of these elements in the activation of CL in topaz. In contrast, no clear correlation was found between CL intensity and F contents, despite the fact that the replacement of OH for F is known to affect the cell parameters of topaz.

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Radiation-induced defects in euclase: formation of O− hole and Ti3+ electron centers

Dias

Pinheiro

2009

Phys Chem Minerals

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Color centers in topaz: comparison between neutron and gamma irradiation

Cited by 23 publications

References 11 publications

Color Dependence on Thickness in Topaz Crystal from Brazil

Color Dependence on Thickness in Topaz Crystal from Brazil

Relation between cathodoluminescence and trace-element distribution of magmatic topaz from the Ary-Bulak massif, Russia

Radiation-induced defects in euclase: formation of O− hole and Ti3+ electron centers

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