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引言稀土氧化物(镧系),虽然构成一族密切相关的化合物,但却显示了各种不同的特征行为和固体性质。其中有些特点使得稀土氧化物成为了催化研究的有意义课题。这些材料的丰度及价格与稀土金属本身相平行,从普通而十分廉价的(如 La_2O_3和 CeO_2)到稀有而比较昂贵的(如 Tm_2O_3和 Lu_2O_3)。所有这些氧化物都是十分耐熔的、不会挥发、具有2000℃以上的熔点;而某些氧化物呈现有一系列复杂的非化学计量组成。这些氧化物,大多数是顺磁
INTRODUCTION Rare earth oxides (lanthanides), while constituting a family of closely related compounds, exhibit a variety of different characteristic behaviors and solid properties. Some of these features make rare earth oxides a significant topic for catalytic research. The abundance and price of these materials are in parallel with the rare earth metals themselves, from ordinary and very cheap (such as La 2 O 3 and CeO 2) to rare and expensive (such as Tm 2 O 3 and Lu 2 O 3). All of these oxides are very refractory, nonvolatile, with a melting point above 2000 ° C, and some oxides exhibit a complex series of non-stoichiometric compositions. Most of these oxides are paramagnetic