Analysis and modification of natural red spinel by ion beam techniques for jewelry applications

Bootkul, D.; Tengchaisri, T.; Tippawan, U.; Intarasiri, S.

doi:10.1016/j.surfcoat.2016.05.084

Cited by 6 publications

(9 citation statements)

References 15 publications

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“…Raman and Photoluminescence spectra of heated spinels demonstrate remarkable changes in their characteristic features. Four Raman peaks are recognized in a red spinel sample at around 306.5-311.4 cm -1 , 406.2 cm -1 , 662.7-672.0 cm -1 , and 761.3-768.9 cm -1 comparable to previous studies (Bootkul et al, 2016;Cynn et al, 1992;Slotznick & Shim, 2008), they assigned these peaks to T2g(1), Eg, T2g(2), and A1g mode, respectively ( Figure 10a) . The full width at half maximum ( FWHM) dominating at around 406 cm -1 peak was suggested to be appropriate for determining natural and heated spinels since disordering of the spinel structure lattice is the expected consequence after heating above 750 o C (Chauviré et al, 2015;Myat Phyo et al, 2019;Peretti et al, 2015;Saeseaw et al, 2009;Widmer et al, 2015).…”

Section: Indication Of Heated Spinelsupporting

confidence: 84%

“…In normal spinels, a strong dominant chromium line with an absorption at 685 nm (R-line) is recognized as well as additional characteristics at 675, 697, 706, 717, and 722 nm ( N-lines) ( Mikenda, 1981;Phan et al , 2004) . However, the most significant change occurs in the intensity of the dominant peak at about 686.9-687.0 nm (N1 line) (Bootkul et al, 2016;Mikenda, 1981;Phan et al, 2004), whereas the other features showed unsharp and unstructured after heating (Figure 11a). Unlike the others, the green sample exhibits no discernible change in the PL spectrum and most likely exhibited comparable characteristics to heated samples in all aspect including a broader 686.…”

Section: Indication Of Heated Spinelmentioning

confidence: 99%

“…Furthermore, the peak at 686.9-687 nm (Figure 11) is referred to as the N1line due to a coupling between the Cr 3+ state and the lattice defect. Broadening and poorly defined structure after heating is due to the interactive processes between Cr 3+ ions and site occupation of the environment as well as an increasing of lattice defects ( disorder in inverse spinels, as mentioned above) ( Bootkul et al , 2016;Mikenda, 1981;Phan et al , 2004) . Thus, with increasing of temperature, the higher the inversion to inverse spinels (disorder) occurs.…”

Section: Indication Of Heated Spinelmentioning

confidence: 99%

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Trace elements and color-causing role in spinel and tanzanite

Pluthametwisute

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This research is aimed to investigate the significant trace elements and their color-causing roles in tanzanite and spinels (7 color varieties) by focusing on their concentrations, valencies, and site occupancy�since no palpable research has been reported previously either before or after heating of both gems. According to this finding, natural tanzanites usually show strongly trichroic colors of violet, blue, and brown in different directions. However, this characteristic is easily changed to violet-blue dichroism after heat treatment. As the result, the violet-blue absorption band (centered around 450460 nm) is obviously decreased after heating, and XAS analysis indicates the higher valency state of vanadium. Consequently, vanadium is strongly suggested as the significant coloring agent in tanzanite which is also supported by its dominant concentration. Based on this finding, natural spinels contain trace elements which may cause various hues. Red color is attributed by the combination of significant Cr and V ratios. Magenta and purple to blue and green colors are affected by significant Fe content, whereas orange color shows contribution to significant V content. After heating, XAS indicates a greater oxidation state as well as disordering of iron and vanadium, while Cr stays consistent. Broadening of the dominant peak at around 406.2 cm-1�and the occurrence of additional small peak at around 715.2-719.8 cm-1�in Raman spectra as well as broadening of the 685 nm and poorly defined structure of additional peaks in photoluminescence spectra are significant indicators of inverse spinels (heated spinel) which strongly benefits gem-testing laboratory to recognize the heat-treated spinel. �

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Section: Indication Of Heated Spinelsupporting

confidence: 84%

Section: Indication Of Heated Spinelmentioning

confidence: 99%

Section: Indication Of Heated Spinelmentioning

confidence: 99%

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Trace elements and color-causing role in spinel and tanzanite

Pluthametwisute

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“…However, Taran et al [61] proposed both Fe 2+ and Fe 3+ . Although the band between 487 and 580 nm is inconsistent, it has been attributed to spin-forbidden transitions of T Fe 2+ [7,11,27,62]. Absorption at 558 nm is attributed to spin forbidden transition 5 E(D) → 3 T 2 (H) of T Fe 2+ [27,58,60,61].…”

Section: -396mentioning

confidence: 99%

Minor Elements and Color Causing Role in Spinel: Multi-Analytical Approaches

et al. 2022

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Natural spinel (MgAl2O44) usually contains some minor and trace elements (e.g., Cr, Co, Fe, V) that may cause various hues. The ratios of these chromophores directly affect the color composition. The red color in spinel is attributed to the combination of significant Cr and V. Magenta and purple to blue and green colors in spinels are affected by the significant Fe concentration, whereas orange color in spinel shows the contribution of significant V content compared to Cr and Fe. After the heating experiment, advanced gemological investigation reveals some noteworthy characteristic features. X-ray absorption spectroscopy (XAS) indicates a greater change in oxidation state, as well as disordering of Fe and V. Broadening of the dominant peak at around 406 cm−1 with occurrences of additional small peaks at around 715–719 cm−1 in Raman spectra, as well as broadening of the 685 nm (R-line) and poorly defined structure of additional peaks (N-lines) in photoluminescence spectra should be significant indicators of spinel undergone heat treatment.

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“…Materials are identified by their properties, and a great part of the game consists in playing with these properties, tuning them in order to optimize both the final product and the way to manufacture it [18]. The tailoring of properties is particularly applicable to gemstones, so as to tune the optical properties, as reported in D. Bootkul et al [19].…”

Section: Introductionmentioning

confidence: 99%

Design and Manufacturing of a Nd-Doped Phosphate Glass-Based Jewel

Pugliese

Gobber

Forno³

et al. 2020

Materials

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This paper reports the results of the designing, manufacturing and characterization of a jewel obtained by means of coupling the dogmas of industrial design to the analytical engineering approach. The key role in the design of the jewel was played by an in-house synthesized Neodymium (Nd)-doped phosphate glass, selected due to its easy handling and capability to change color according to the incident light wavelength. The glass core was covered by a metal alloy to mitigate its relatively high fragility and sensitivity to thermal shock and, at the same time, to highlight and preserve its beauty. The selection of the proper metal alloy, having thermo-mechanical properties compatible with those exhibited by the glass, was carried out by means of Ashby’s maps, a powerful tool commonly adopted in the field of industrial design.

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Analysis and modification of natural red spinel by ion beam techniques for jewelry applications

Cited by 6 publications

References 15 publications

Trace elements and color-causing role in spinel and tanzanite

Trace elements and color-causing role in spinel and tanzanite

Minor Elements and Color Causing Role in Spinel: Multi-Analytical Approaches

Design and Manufacturing of a Nd-Doped Phosphate Glass-Based Jewel

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