Synergetic Surface and Chemical Durability Study of the Aesthetically Enhanced Natural Quartz by Heat Treatment
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TRODUCTION
QUARTZ is one of the most abundant minerals found in Earth’s crust (around 12 pct). Though quartz is chemically inert, the changes in pressure (P)–temperature (T) conditions cause variations in its crystallographic structure.[1] The thermal luminescence property of this mineral makes it a technological material in radiation science and engineering. In dosimetry, quartz is used in testing the authenticity of art objects, nuclear accidents,[2] food irradiation control,[3] and dating of archeological materials and sediments.[4–6] Recent studies show that quartz is used in various advanced applications such as quartz cement,[7] quartz crystal microbalance sensors,[8] quartz crystal with transparent electrode used for localized surface plasmon resonance (SPR) sensing with quartz crystal microbalance with dissipation monitoring technology,[9] paramagnetic lattice defects in quartz for applications to electron spin resonance dating for advance applications to fault gouge, tephra and sediment,[10] radio fluorescence,[11] as a sensor for detection of ammonia in human breath,[8] photoacoustic spectroscopy,[12] and tuning fork-based conductive atomic force microscopes with glue-free solid metallic tips.[13] RAKESH K. SAHOO, SAROJ K. SINGH, BARADA K. MISHRA, and BIRENDRA K. MOHAPATRA are with the CSIR Institute of Minerals and Materials Technology, Bhubaneswar 751013, India. Contact email: [email protected] PRAJNA P. ROUT, formerly with the CSIR - Institute of Minerals and Materials Technology, is now with the Department of Physics, Government Polytechnic, Moto, Puri, Odisha 752011, India. Manuscript submitted April 22, 2016. Article published online January 17, 2017 METALLURGICAL AND MATERIALS TRANSACTIONS A
The optical, thermal, piezoelectric properties make natural quartz an interesting material for technological and gemological applications. Defects, vacancies, and impurities, basically Al, Fe, Ti, Na, K, Zn, Ge, P, etc., adversely affect all the preceding properties.[14,15] The gemological quality of the quartz demands an attractive color and durability. The color of the natural quartz is modified using several methods such as dying, heating, irradiation, etc. Coloration of quartz crystals is possible through the incorporation of transition metal impurities such as V3+ for royal blue, Cr3+ for green, Ni3+ for green fluorescence, Cu2+ for yellow-green fluorescence, Co2+ for blue, and Fe3+ for amber-brown.[16] The possibility to dope quartz by thermal diffusion is an interesting issue from both technological and scientific points of view. In this study, we compare the aesthetic value and surface diffusion characteristics of the natural quartz by thermal diffusion of metallic ions in quartz samples, which were collected from the Nuapada district of Odisha. Quartz in two different colors, i.e., light blue and pink, has a high market value and can be treated as a low-price version of the blue topaz and citrine. Hence, a simple attempt is carried out to study the change in surface color and luster of the natural
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