一、前言希土元素是指原子序数从57到71的15个元素而言。所谓“希”是在自然界由提取这类元素的矿物很少;所谓“土”是它们的成盐氧化物成土状,类似土族元素氧化物。如CaO和Al_2O_3,它们的原子结构相似,表现在化学和物理性质上都十分相近,故往往放在一起,统称为希土元素或希土金属,因为第一个元素是 First, the preface Greek elements refers to the atomic number from 57 to 71 in terms of the 15 elements. The so-called “hope” is in nature by the extraction of such elements of the minerals is very small; the so-called “soil” is their salt-forming oxide into soil, similar to soil oxide. Such as CaO and Al 2 O 3, their atomic structure is similar to the performance of the chemical and physical properties are very similar, it is often put together, collectively referred to as the Greek soil element or the Greek soil metal, because the first element is