Preparation of Pure Crystalline Indium and its Characterization

DOI : http://dx.doi.org/10.13005/msri/050112

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In this study multi-pass zone refining technique was employed to purify indium metal from 3N+ to 5N6 purity level and the refined samples were characterized for their purity and crystalline quality. Major impurities that were targeted for reduction by multi-pass zone-refining include Al, As, Bi, Ca, Mg, Sb, Si, Sn, Ge, Pb, Ga, Cu, Fe, Zn and Ag. The samples were initially homogenized by following a three-cycle melting (heating) and solidification (cooling) scheme. A five pass pre-stage zone-refining experiment(s) of five hours duration on pre-homogenized samples were conducted employing Instrolec 200 zone-refiner. Parameters such as heater temperature, traverse speed, coolant flow and time were optimized. Indium samples obtained from the pre-stage zone-refining process were chemically washed, cleaned and then loaded in the Instrolac PTFE sample tube for final an eight-pass zone refining process. Starting and final stage zone-refined indium samples were characterized by ICP-OES, ICP-MS and XRD. It was found that, the total concentration of impurities reduced from 91.43 ppm to 14.465 ppm after 5 passes and to 4.02 ppm (5N6-99.9996% pure) after 8 passes and the results are discussed.

Zone-refining; High pure indium; purity analysis