Microwave heat treatment of natural ruby and its characterization
- 1.1k Downloads
Natural ruby (in the form of gemstone) collected from Odisha has been heat-treated by microwave (MW). A 3-kW industrial MW furnace with SiC susceptors was used for the heat treatment. The ruby samples showed noticeable improvements (qualitative), may be attributed to account for the improvement in clarity and lustre. Optical absorption in 200–800 nm range and photoluminescence peak at 693 nm (with 400 nm λ ex) clearly show that subtle changes do take place in the ruby after the heat treatment. Further, inorganic compound phases and valence states of elements (impurities) in the ruby were studied by X-ray diffraction, micro-Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The valence states of the main impurities such as Cr, Fe, and Ti, in the untreated and MW heat-treated ruby, as revealed from XPS, have been discussed in depth. The overall results demonstrate for the first time the effect of fast heating like MW on the microstructural properties of the gemstone and various oxidation states of impurity elements in the natural ruby.
KeywordsRuby Fluorescence Lifetime Conventional Heating Method Blue Patch TiO2 Cluster
Financial support of CSIR for this work carried out under Project ESC-206 is thankfully acknowledged.
- 8.R.R. Menezes, P.M. Souto, R.H.G.A. Kiminami, in Sintering of Ceramic Materials—New Emerging Techniques, ed. by A. Lakshmanan (InTech, Rijeka, Croatia, 2012), p. 3Google Scholar
- 13.S.M. Bradshaw, E.J. van Wyk, J.B. de Swardt, J. South Afr. Inst. Min. Metall. 4, 201 (1998)Google Scholar
- 17.Y. Takeuchi, T. Abe, T. Kageyama, H. Sakai, in Proceedings of the Particle Accelerator Conference, IEEE, vol 1195 (2005)Google Scholar
- 19.T.A. Baeraky, Egypt J. Solid 25, 263 (2002)Google Scholar
- 25.T.V. Bgasheva, E.A. Ahmetshin, E.V. Zharikov, Adv. Mater. Sci. 12, 32 (2012)Google Scholar
- 29.K.T.V. Grattan, Z.Y. Zhang, Fiber Optic Fluorescence Thermometry, 1st edn. (Chapman & Hall, London, 1995), p. 35Google Scholar
- 30.C.D. Wagner, W.M. Riggs, L.E. Davis, G.E. Muilenberg (eds.), Handbook of X-ray Photoelectron Spectroscopy (Perkin-Elmer Corporation, Minnesota, 1978)Google Scholar