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鉛的去鉍可以用沉淀精炼的方法,用Ca,Mg,K等金属为沉淀剂,生成的金属間化合物有Mg_3Bi_2(s),Ca_3Bi_2(s),CaMg_2Bi_2(s)及K_9Mg_6Bi_7(s)等。本文目的是利用已有数据計算这些金属間化合物的标准生成自由能,以期对沉淀去鉍过程获得进一步的了解。从Mg-Bi相图可見,在液相綫上Mg_3Bi_2(s)与熔液成平衡。因此,可以从Mg-Bi系的活度数据結合相图计算Mg_3Bi_2(s)的标准生成自由能,同样方法曾被用来計算InSb(s)的标准生成自由能。液相綫上的平衡可以用下式表示:
Lead to bismuth can be precipitated by precipitation method, with Ca, Mg, K and other metals as precipitants, the resulting intermetallic compounds are Mg_3Bi_2 (s), Ca_3Bi_2 (s), CaMg_2Bi_2 (s) and K_9Mg_6Bi_7 (s) and so on. The purpose of this paper is to use the available data to calculate the standard free energy of these intermetallic compounds in order to gain a better understanding of the precipitation of de-bismuth. As can be seen from the Mg-Bi phase diagram, Mg_3Bi_2 (s) equilibrates with the melt on the liquidus. Therefore, the standard free energy of Mg 3 Bi 2 (s) can be calculated from the activity data of Mg-Bi system in combination with the phase diagram. The same method has been used to calculate the standard free energy of formation of InSb (s). The balance on the liquidus can be expressed as: