Europium substituted yttrium

Europium-Substituted Yttrium Hydrazine Carboxylate Hydrate... 

Another significant development was the superconducting system of a mixed oxide of yttrium reported by Wu, Chu and co-workers. The compound has a formula YBa CujO, where x is between 6 and 7 and a T, 93 K which means that the expensive liquid helium can be replaced by cheap liquid nitrogen (77 K). For simplicity, the above system is called the 1-2-3 system based on the ratio of the metals present. This also has a perovskite structure. Similar compounds substituting yttrium by other lanthanides like europium, samarium etc., are known. These are called warm superconductors. A lot of research to obtain high T are going on and superconductors with Tj, as high as 164 K have been reported. 

The complex Yo.99Euo.oi(N2H3COO)3-3H20 decomposes in air at 600 °C to form the corresponding europium-doped yttrium oxide. The decomposition temperature can be reduced, however, by mixing the redox compound with a calculated amount of either ammonium nitrate (1 6) or ammonium perchlorate (1 2.4) and rapidly heating the mixture at 300 °C to obtain Eu -substituted Y2O3 - the red phosphor. 

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