Color Change of Spodumene Gemstone by Electron Beam Irradiation

Abstract:

Study on the electron beam irradiation color change induction of spodumene (LiAlSi₂O₆) samples, which color exhibit green, pink and colorless. Characteristic the electron-beam irradiation dose were selected 30,000 kGy, 40,000 kGy and 50,000 kGy. The color and fading of spodumene samples were analyzed by UV-VIS spectrophotometer , crystal structure were determined by X-ray diffraction (XRD) spectrometer, free radical species of impurities were determined by Electron Spin Resonance (ESR) spectrometer before and after irradiation. The results revealed the color of spodumene samples changed after irradiation, from green spodumene became a little darker color, pink spodumene became green color, colorless spodumene became pink to purple color the results of the color analysis and fading displayed on the CIE L* a* b* color system, color change spodumene samples were determined by values changed of a* and b*. Color fade of spodumene were determined by values changed of L*. The results of all samples crystal structure analysis were shown on the XRD patterns of the JCPDS No. 89-6662 (Spodumene) with monoclinic structure. The radical analysis results of impurity elements, green and pink only appear the ESR pattern of manganese (Mn²⁺), and chromium (Cr³⁺), respectively. It can be conclusion that intensity of color change depend on the irradiation dose and impurity elements in spodumene samples.

• Periodical: Advanced Materials Research (Volume 770)
• Pages: 370-373
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.770.370
• Online since: September 2013
• Authors: Pannipa Noithong, Panee Pakkong, Kittisakchai Naemchanthara
• Keywords: e-Beam, ESR, Fading, Spodumene, X-Ray Diffraction (XRD)

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