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Y(VP)O_4:Eu萤光粉中的稀土主要是钇和铕.本文拟定的方法是在pH5左右,以二甲酚橙为指示剂,EDTA络合滴定钇、铕总量;用氧化还原法测定铕;再用差减法求得钇的含量。铕是三价稀土元素中唯一可以被锌还原成低价的元素,本法利用锌把混合稀土中Eu~(3+)还原成Eu~(2+),Eu~(2+)被过量的Fe~(3+)溶液吸收,被还原出来的Fe~(2+)用重铬酸钾标准溶液滴定。关于锌汞齐还原铕,过去曾有报导,但利用液态锌汞齐、保护气氛等,设备、操作均较繁复。有的方法利用Fe~(3+)直接滴定
The rare earths in Y (VP) O_4: Eu phosphor are mainly yttrium and europium.The proposed method is to titrate the total amount of yttrium and europium with xylenol orange as indicator and EDTA complex at pH5, Method for the determination of europium; and then subtract method for the yttrium content. Europium is the only one of trivalent rare earth elements that can be reduced to a lower price by zinc. In this method, Eu ~ (3 +) is reduced to Eu ~ Fe ~ (3 +) solution is absorbed, the reduced Fe ~ (2+) titration with potassium dichromate standard solution. On the reduction of europium zinc amalgam, in the past have been reported, but the use of liquid zinc amalgam, the protection of the atmosphere, equipment, operation more complicated. Some methods use Fe ~ (3 +) direct titration