摘要 : Properties of trivalent rare earth ions have been extensively understood. Besidesthe +3 valent state, the rare earth elements also have +4, +2 and +1 valencies,clusters and mixture valent compounds. The research of their synthesis... 展开 Properties of trivalent rare earth ions have been extensively understood. Besidesthe +3 valent state, the rare earth elements also have +4, +2 and +1 valencies,clusters and mixture valent compounds. The research of their synthesis, structure,properties of unusual valent rare earth compounds has theoretical and practicalsignificance. It will broaden the horizon of rare earth chemistry and extend 收起