Influence of thermal treatment on the Raman, infrared and TL responses of natural topaz

Souza, Divanízia do Nascimento; Lima, José Fernandes de; Valério, Mário E.G.; Fantini, C.; Pimenta, M. A.; Moreira, R. L.; Caldas, Linda V.E.

doi:10.1016/s0168-583x(02)00566-9

Cited by 24 publications

(10 citation statements)

References 9 publications

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“…As it was reported by other authors (Souza et al, 2002;Dantas et al, 2006), the emission bands of both topaz and quartz are similar and two color centers are mentioned, namely, (AlO 4 ) 0 and (H 3 O 4 ) 0 emitting at 460 and 380 nm, respectively. In Fig.…”

Section: Uv and Visible Bleachingsupporting

confidence: 81%

Caracterización de materiales luminiscentes tejido-equivalentes para la detección de radiación ionizante

Jiménez¹

2022

RIDAA Tesis Unicen

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De manera general, la detección de radiación ionizante se realiza a través de diferentes dosímetros como son: las cámaras de ionización (CI), los diodos, los dosímetros termoluminiscentes (TLD) y los de luminiscencia estimulada ópticamente (OSL), entre otros. Aunque las cámaras de ionización se utilizan en todos los centros de radioterapia, su uso es exclusivo en dosimetría física, la cual se realizan en fantomas de agua, que simulan la consistencia y la densidad de un órgano humano vivo. Las CI son de gran tamaño (∼27mm), necesitan correcciones por recombinación iónica, son frágiles, precisan cableado y presentan dependencia con la energía, lo cual dificulta su implementación en dosimetría clínica. Los diodos son frecuentemente utilizados debido a su tamaño pequeño y medición en tiempo real, no obstante, su respuesta presenta fluctuaciones con la temperatura, exhiben pérdida de sensibilidad con la dosis acumulada, necesitan ser pre-irradiados, deben ser calibrados para cada energía a utilizar y no son tejido-equivalentes. Los TLD son ampliamente utilizados por su buena equivalencia con el tejido biológico, su alta sensibilidad y su posibilidad de reutilización. A pesar del amplio uso de estos dosímetros, diversas organizaciones están migrando hacia la dosimetría OSL debido a las ventajas dosimétricas que posee con respecto a la TLD. Párrafo extraído de la tesis de posgrado a modo de resumen.

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Section: Uv and Visible Bleachingsupporting

confidence: 81%

Caracterización de materiales luminiscentes tejido-equivalentes para la detección de radiación ionizante

Jiménez¹

2022

RIDAA Tesis Unicen

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“…IR absorption spectra of Co diffused and colourless topaz depicted five distinct IR absorption bands clustered around 1000-2050, 2300-3000, 3300-4100, 4200-4850, and 6000-7000 cm -1 (Figure 6). IR absorption peaks observed in 1000-2050 cm -1 region are attributed to stretching of Al-O bonds and Si-O bonds in the topaz matrix [16,35]. Similar bands were also observed by Smith (1995) [36] due to Al-O bonds in corundum.…”

Section: Results Of Ir Absorption Spectrasupporting

confidence: 65%

“…Other contradictory feature of Co diffused topaz is slightly low intensity of peaks at 3351 cm -1 and 3453 cm -1 than colorless topaz. Past research have emphasized that, peak intensity associated with OH groups attached to the lattice defects of the topaz was decreased with temperature [35,43]. Therefore, this newly obtained IR absorption data have clearly shown that "defective" hydroxyl content has reduced with temperature that has been applied in the cobalt diffusion process.…”

Section: Results Of Ir Absorption Spectramentioning

confidence: 62%

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Optimized conditions for cobalt diffusion in Sri Lankan colorless topaz and coloration mechanism elucidation through spectro-chemical investigation

et al. 2023

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Most of natural topaz is colorless; thus, methods of color enhancement are widely used for coloring this mineral. Currently, blue color is obtained by cobalt diffusion due to drawbacks in existing coloration methods. In this study, optimum conditions suitable for Cobalt diffusion in Sri Lankan colorless topaz were investigated and coloration mechanism was elucidated. The diffusion agent was prepared by mixing CoCO3 with Na2CO3, CaCO3 and carbon powder and diffusion was carried-out by varying the temperature and soaking time. Chemical analysis, UV-Vis absorption spectrum, infrared absorption spectra, and Raman peaks of diffused and non-diffused topaz were tested. The results clearly indicated that the optimum condition for Co diffusion in Sri Lankan topaz is 950℃ for 11 h. The EPMA analysis showed that the Co concentration in the diffused sample varied from 0.001 wt% to 0.027 wt% while colorless topaz showed <0.001 wt%. The UV-Vis spectrum of Co diffused blue topaz gave three absorption peaks at 556, 588, and 627 nm corresponding to three spin-allowed electronic transitions of Co2+ ion in teterahedaral coordination. In case of Co diffused topaz, one additional new broader IR absorption peak was noticed around 6640 cm-1 presumably arising by optical transitions of 4A2 → 4T1 in Co2+ (4F). Our results lead to the conclusion that, blue color of the Co diffused topaz is arising by spin-allowed electronic transitions of Co2+ ions in tetrahedral site of topaz matrix through substitution of Si4+ ions.

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“…Four of the six anions surrounding the Al 3þ ion belong to SiO 4 tetrahedral, and the remaining two belong either to an F À group or an OHgroup. [5] In this sense, this paper reports about the influence of the temperature on the thermoluminescence (TL) and cathodoluminescence (CL) behavior of a chemical and structurally well-characterized topaz from Badajoz (Spain) by means of X-ray fluorescence (XRF) and X-ray diffraction (XRD). TL provides information about the trapped charge recombination sites related to metastable defects inside the lattice depending on whether the detrapping process is due to heat.…”

Section: Introductionmentioning

confidence: 99%

Thermal Effect on the Cathodo- and Thermoluminescence Emission of Natural Topaz (Al₂SiO₄(F,OH)₂)

Correcher

García-Guinea

Martin-Fernandez

et al. 2011

Spectroscopy Letters

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The authors report about the influence of temperature on the thermoluminescence (TL) and cathodoluminescence (CL) behavior of a well-characterized topaz from Badajoz, Spain. Cryogenic treatments induce drastic decrease on the CL and TL intensity over 400 nm involving O Al Ã intrinsic defects and iron point defects. It suggests that low-energy emissions should be more associated with point defects and low wavebands to structural or intrinsic defects in the lattice. The tests of thermal stability of the UV-blue TL signal at different temperatures (in the range of 473-673 K) seem to confirm a continuous trap distribution system.

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Influence of thermal treatment on the Raman, infrared and TL responses of natural topaz

Cited by 24 publications

References 9 publications

Caracterización de materiales luminiscentes tejido-equivalentes para la detección de radiación ionizante

Caracterización de materiales luminiscentes tejido-equivalentes para la detección de radiación ionizante

Optimized conditions for cobalt diffusion in Sri Lankan colorless topaz and coloration mechanism elucidation through spectro-chemical investigation

Thermal Effect on the Cathodo- and Thermoluminescence Emission of Natural Topaz (Al₂SiO₄(F,OH)₂)

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Influence of thermal treatment on the Raman, infrared and TL responses of natural topaz

Cited by 24 publications

References 9 publications

Caracterización de materiales luminiscentes tejido-equivalentes para la detección de radiación ionizante

Caracterización de materiales luminiscentes tejido-equivalentes para la detección de radiación ionizante

Optimized conditions for cobalt diffusion in Sri Lankan colorless topaz and coloration mechanism elucidation through spectro-chemical investigation

Thermal Effect on the Cathodo- and Thermoluminescence Emission of Natural Topaz (Al2SiO4(F,OH)2)

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Thermal Effect on the Cathodo- and Thermoluminescence Emission of Natural Topaz (Al₂SiO₄(F,OH)₂)