Thermal properties of europium nitrate hexahydrate Eu(NO3)(3)center dot 6H(2)O

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作   者：

Melnikov, P.;  Arkhangelsky, I. V.;  Nascimento, V. A.;  de Oliveira, L. C. S.;  Silva, A. F.;  Zanoni, L. Z.; 

作者机构：

MS;  Campo Grande;  Univ Fed Mato Grosso do Sul;  Brazil; 

关键词：

Oxynitrates;  Thermal decomposition;  Rare earth;  Europium nitrate hexahydrate; 

期刊名称：

Journal of thermal analysis and calorimetry

i s s n：

1388-6150

年卷期：

2017 年 128 卷 3 期

页   码：

1353-1358

页   码：

摘   要：

The hexahydrate of europium nitrate hexahydrate Eu(NO3)(3)center dot 6H(2)O shows no phase transitions in the range of -40 to 76 A degrees C when it melts in its own water of crystallization. It was shown that the thermal decomposition is a complex step-wise process, which starts with the simultaneous condensation of 6 mol of the initial monomer Eu(NO3)(3)center dot 6H(2)O into a cyclic cluster 6[Eu(NO3)(3)center dot 6H(2)O]. This hexamer gradually loses water and nitric acid, and a series of intermediate amorphous oxynitrates is formed. The removal of HNO3 azeotrope is essentially a continuous process occurring in the liquid phase. At higher temperatures, oxynitrates undergo further degradation, lose water, nitrogen dioxide, and oxygen, and finally, after having lost lattice water, are transformed into europium oxide. All mass losses are satisfactorily accounted for under the proposed scheme of thermal decomposition.