稀土元素,包括元素周期表中15种镧系元素。即镧(La)、铈(Ce)、镨(Pr)、钕(Nd)、钷(Pm)、钐(Sm)、铕(Eu)、钆(Gd)、铽(Tb)、镝(Dy)、钬(Ho)、铒(Er)、铥(Tm)、镱(Yb)和镥(Lu)。由于钇(Y)和钪(Sc)的化学性质与它们很相近,所以也归属于此类。这17种元素的物理和化学性质很接近,在自然界,它们总是伴生在一起,用普通的化学方法极难使它们分开,因此,大部分稀土金属都是当做“混合金属”生产的。 Rare earth elements, including 15 kinds of lanthanides in the periodic table. Namely La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, , Holmium, Er, Tm, Yb and Lu. Yttrium (Y) and scandium (Sc) due to their chemical properties are similar to them, so also belong to this category. The 17 elements are very close in physical and chemical properties. In nature, they are always associated and are difficult to separate by ordinary chemical methods. Therefore, most rare earth metals are produced as “mixed metals.”