Effect of Heat Treatment and Electron Beam Irradiation Tourmaline: UV-Visible, EPR, and Mid-IR Spectroscopic Analyses

Apichate MANEEWONG, Kanwalee PANGZA, Nongnuch JANGSAWANG, Tasanee CHAROENNAM

Abstract


The origin of the color change in 3 types of tourmaline gemstones, 2 pink samples from Afghanistan and one green sample from Nigeria, was examined by using UV-Vis, FTIR, EPR, and EDXRF spectroscopy. After heating at a temperature of 600 °C in air, the color of pink tourmaline gemstone changed to become colorless. This colorless tourmaline recovered its pink color by being irradiated with 800 kGy of electrons (e-beam). The UV-Vis absorption spectrum of the pink tourmaline with higher Mn concentration (T2, 0.24 wt%) showed characteristic absorption peaks originating from the Mn3+ color center: 2 absorption bands centered at wavelengths of 396 and 520 nm. Both absorption bands disappeared after heat treatment in air at 600 °C, and then displayed again after e-beam irradiation at 800 kGy. EPR spectra of T2 showed that the color change was related to the valence change of Mn3+ to Mn2+ ions and vice versa. The pink tourmaline of lower MnO content (T1, 0.08 wt%) also changed to being colorless with heat treatment, but the color was not recovered by e-beam irradiation. Instead, a yellow color was obtained. UV-Vis and FTIR spectra indicated that this yellow color originated from the decomposition of the hydroxyl group (-OH) into O- and Ho by the e-beam irradiation. Green tourmaline did not show any color change with the heat treatment or the e-beam irradiation.


Keywords


Tourmaline, heat and electron treatment, UV-Vis, EPR, FTIR

Full Text:

PDF

References


C Castaneda, EF Oliveira, N Gomes and ACP Soares. Infrared study of OH sites in tourmaline from the elbaite-schorl series. Am. Mineral. 2000; 85, 1503-7.

K Krambrock, MVB Pinheiro, SM Medeiros, KJ Guedes, S Schweizer and JM Spaeth. Investigation of radiation-induced yellow color in tourmaline by magnetic resonance. Nucl. Instrum. Meth. B 2002; 191, 241-5.

BJ Reddy, RL Frost, WN Martens, DL Wain and JT Kloprogge. Spectroscopic characterization of Mn-rich tourmalines. Vib. Spectros. 2007; 44, 42-9.

C Castaneda, SG Eeckhout, GMD Costa, NF Botelho and ED Grave. Effect of heat treatment on tourmaline from Brazil. Phys. Chem. Mineral. 2006; 33, 207-16.

P Bačík, D Ozdín, M Miglierini, P Kardošová, M Pentrák and J Haloda. Crystallochemical effects of heat treatment on Fe-dominant tourmalines from Dolni Bory (Czech Republic) and Vlachovo (Slovakia). Phys. Chem. Mineral. 2011; 38, 599-611.

GH Faye, PG Manning, JR Gosselin and RJ Tremblay. The optical absorption spectra of tourmaline: Importance of charge-transfer processes. Can. Mineral. 1974; 12, 370-80.

MBD Camargo and S Isotani. Optical absorption spectroscopy of natural and irradiated pink tourmaline. Am. Mineral. 1988; 73, 172-80.

IM Reinitz and GR Rossman. Role of natural radiation in tourmaline colouration. Am. Mineral. 1988; 73, 822-5.

I Petrov. Role of natural radiation in tourmaline coloration: Discussion. Am. Mineral. 1990; 75, 237-9.

BM Laurs, JC Zwaan, CM Breeding, WB Simmons, D Beaton, KF Rijsdijk, R Befi and AU Falster. Copper-bearing (Paraiba-type) tourmaline from Mozambique. Gem. Gemol. 2008; 44, 4-30.

YK Ahn, JG Seo and JW Park. Electronic and vibrational spectra of tourmaline - The impact of electron beam irradiation and heat treatment. Vib. Spectros. 2013; 65, 165-75.

PG Manning. Effect of second-nearest-neighbor interaction on Mn3+ absorption in pink and black tourmalines. Can. Mineral. 1973; 11, 971-7.

GR Rossman and SM Mattson. Yellow Mn-rich elbaite with Mn-Ti intervalence charge transfer. Am. Mineral. 1986; 71, 599-602.

DM Sherman and N Vergo. Optical spectrum, site occupancy and oxidation state of Mn in montmorillonite. Am. Mineral. 1988; 73, 140-4.

GH Faye, PG Manning and EH Nickel. The polarized optical absorption spectra of tourmaline, cordierite, chloritoid and vivianite: Ferrous-ferric electronic interaction as a source of pleochroisim. Am. Mineral. 1968; 53, 1174-201.

SM Mattson and GR Rossman. Fe2+-Fe3+ interactions in tourmaline. Phys. Chem. Mineral. 1987; 14, 163-71.

GR Rossman, E Fritsch and JE Shigley. Origin of color in cuprian elbaite from São José de Batalha, Paraíba, Brazil. Am. Mineral. 1991; 76, 1479-84.

G Smith. Evidence for absorption by exchange-coupled Fe2+-Fe3+ pairs in the near infra-red spectra of minerals. Phys. Chem. Mineral. 1978; 3, 375-83.

N Srisittipokakun, C KedKaew, J Kaewkhao, T Kittiauchawal, K Thamaphat and P Limsuwan. Electron spin resonance (ESR) and optical absorption spectra of a manganese doped soda-lime-silicate glass system. Kasetsart J. Nat. Sci. 2009; 43, 360-4.

RPS Chakradhar, G Sivaramaiah, JL Rao and NO Gopal. EPR and optical investigations of manganese ions in alkali lead tetraborate glasses. Spectrochim Acta A 2005; 62, 761-8.

RS Muralidharaa, CR Kesavulub, JL Raob, RV Anavekara and RPS Chakradharc. EPR and optical absorption studies of Fe3+ ions in sodium borophosphate glasses. J. Phys. Chem. Solids 2010; 71, 1651-5.

J Babiñska, K Dyrek, A Pieczka and Z Sojka. X and Q band EPR studies of paramagnetic centres in natural and heated tourmaline. Eur. J. Mineral. 2008; 20, 233-40.

SP Chaudhuri and SK Patra. Electron paramagnetic resonance and Mössbauer spectroscopy of transition metal ion doped mullite. J. Mater. Sci. 2000; 35, 4735-41.

T Gonzalez-Carrefio and M Fernandez. Infrared and electron microprobe analysis of tourmalines. J. Sanz. Phys. Chem. Mineral. 1988; 15, 452-60.

X Liu, X Feng, J Fan and S Guo. Optical absorption spectra of tourmaline crystals from Altay, China. Chin. Opt. Lett. 2011; 9, 083001.

D Cao, G Zhao, Q Dong, J Chen, Y Cheng, Y Ding and J Zou. Effects of annealing on luminescence efficiency of large-size YAG: Ce crystal grown by temperature gradient techniques. Chin. Opt. Lett. 2010; 8, 199-201.


Refbacks

  • There are currently no refbacks.




http://wjst.wu.ac.th/public/site/images/admin/image012_400

Online ISSN: 2228-835X

http://wjst.wu.ac.th

Last updated: 12 August 2019