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Article

Effect of Diamond Polishing and Thermal Treatment on Carbon Paramagnetic Centers’ Nature and Structure

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Department of Chemical Sciences, Faculty of Natural Sciences, Ariel University, Ariel 4077625, Israel
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The Israeli Diamond Bourse, Dianer Diamonds Company Ltd., Ramat Gan 5252005, Israel
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The Eastern R&D Center, Ariel University, Ariel 4077625, Israel
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Department of Chemical Engineering, Ariel University, Ariel 4077625, Israel
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Department of Chemistry and Institute of Nanotechnology & Advanced Materials, Faculty of Exact Sciences, Bar Ilan University, Ramat Gan 5290002, Israel
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Department of Chemistry, Faculty Natural Sciences, Ben Gurion University of the Negev, Beer Sheva 8410501, Israel
*
Author to whom correspondence should be addressed.
Academic Editors: Cyril Popov and Alexander N. Obraztsov
Materials 2021, 14(24), 7719; https://doi.org/10.3390/ma14247719
Received: 7 November 2021 / Revised: 23 November 2021 / Accepted: 6 December 2021 / Published: 14 December 2021
(This article belongs to the Section Carbon Materials)
Diamonds contain carbon paramagnetic centers (stable carbon radicals) in small concentrations (at the level of ~1 × 1012 spins/mg) that can help in elucidating the structure of the nitrogen atoms’ contaminants in the diamond crystal. All diamonds that undergo polishing are exposed to high temperatures, owing to the friction force during the polishing process, which may affect the carbon-centered radicals’ concentration and structure. The temperature is increased appreciably; consequently, the black body radiation in the visible range turns orange. During polishing, diamonds emit an orange light (at a wavelength of about 600 nm) that is typical of a black body temperature of 900 °C or higher. Other processes in which color-enhanced diamonds are exposed to high temperatures are thermal treatments or the high-pressure, high-temperature (HPHT) process in which the brown color (resulting from plastic deformation) is bleached. The aim of the study was to examine how thermal treatment and polishing influence the paramagnetic centers in the diamond. For this purpose, four rough diamonds were studied: two underwent a polishing process, and the other two were thermally treated at 650 °C and 1000 °C. The diamonds were analyzed pre- and post-treatment by EPR (Electron Paramagnetic resonance), FTIR (Fourier transform infrared, fluorescence, and their visual appearance. The results indicate that the polishing process results in much more than just thermal heating the paramagnetic centers. View Full-Text
Keywords: diamond treatments; EPR spectroscopy; paramagnetic centers diamond treatments; EPR spectroscopy; paramagnetic centers
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MDPI and ACS Style

Litvak, I.; Cahana, A.; Anker, Y.; Ruthstein, S.; Cohen, H. Effect of Diamond Polishing and Thermal Treatment on Carbon Paramagnetic Centers’ Nature and Structure. Materials 2021, 14, 7719. https://doi.org/10.3390/ma14247719

AMA Style

Litvak I, Cahana A, Anker Y, Ruthstein S, Cohen H. Effect of Diamond Polishing and Thermal Treatment on Carbon Paramagnetic Centers’ Nature and Structure. Materials. 2021; 14(24):7719. https://doi.org/10.3390/ma14247719

Chicago/Turabian Style

Litvak, Ira, Avner Cahana, Yaakov Anker, Sharon Ruthstein, and Haim Cohen. 2021. "Effect of Diamond Polishing and Thermal Treatment on Carbon Paramagnetic Centers’ Nature and Structure" Materials 14, no. 24: 7719. https://doi.org/10.3390/ma14247719

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