State Key Laboratory of New Ceramics and Fine Processing, Department of Chemistry, Tsinghua University, Beijing 100084, PR China.
Chem Asian J. 2010 Apr 1;5(4):925-31. doi: 10.1002/asia.200900499.
The decomposed regularity of rare-earth nitrates in octadecylamine (ODA) is discussed. The experimental results show that these nitrates can be divided into four types. For rare-earth nitrates with larger RE(3+) ions (RE=rare earth, La, Pr, Nd, Sm, Eu, Gd), the decomposed products exhibited platelike nanostructures. For those with smaller RE(3+) ions (RE=Y, Dy, Ho, Er, Tm, Yb), the decomposed products exhibited beltlike nanostructures. For terbium nitrate with a middle RE(3+) ion, the decomposed product exhibited a rodlike nanostructure. The corresponding rare-earth oxides, with the same morphologies as their precursors, could be obtained when these decomposed products were calcined. For cerium nitrate, which showed the greatest differences, flowerlike cerium oxide could be obtained directly from decomposition of the nitrate without further calcination. This regularity is explained on the basis of the lanthanide contraction. Owing to their differences in electron configuration, ionic radius, and crystal structure, such a nitrate family therefore shows different thermolysis properties. In addition, the potential application of these as-obtained rare-earth oxides as catalysts and luminescent materials was investigated. The advantages of this method for rare-earth oxides includes simplicity, high yield, low cost, and ease of scale-up, which are of great importance for their industrial applications.
探讨了十八胺（ODA）中硝酸盐的分解规律。实验结果表明，这些硝酸盐可以分为四类。对于具有较大 RE(3+)离子（RE=稀土，La、Pr、Nd、Sm、Eu、Gd）的硝酸盐，其分解产物呈现出片状纳米结构。对于具有较小 RE(3+)离子（RE=Y、Dy、Ho、Er、Tm、Yb）的硝酸盐，其分解产物呈现出带状纳米结构。对于具有中间 RE(3+)离子的硝酸铽，其分解产物呈现出棒状纳米结构。当这些分解产物被煅烧时，可以得到具有相同形态的相应稀土氧化物。对于硝酸铈，它表现出最大的差异，可以直接从硝酸盐的分解中得到花状的氧化铈，而无需进一步煅烧。这种规律可以基于镧系收缩来解释。由于它们在电子构型、离子半径和晶体结构上的差异，因此这样的硝酸盐家族表现出不同的热解性质。此外，还研究了这些获得的稀土氧化物作为催化剂和发光材料的潜在应用。该方法用于制备稀土氧化物的优点包括简单、产率高、成本低且易于放大，这对于它们的工业应用非常重要。
