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High Temperature Phase and Thermal Expansion of PrBr 3
Author(s) -
Krämer Karl W.,
Keller Lukas
Publication year - 2009
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/zaac.200801407
Subject(s) - thermal expansion , neutron diffraction , materials science , diffraction , melting point , phase (matter) , phase transition , atmospheric temperature range , thermal stability , anisotropy , crystallography , analytical chemistry (journal) , chemistry , thermodynamics , composite material , crystal structure , optics , physics , organic chemistry , chromatography
The thermal expansion and phase transition of PrBr 3 was investigated by neutron diffraction and DSC measurements. PrBr 3 has a low‐temperature (LT) UCl 3 ‐type modification and a high‐temperature (HT) PuBr 3 ‐type modification. The stability range and structure of the HT phase were established for the first time by diffraction experiments. The thermal expansion of the LT modification was investigated by powder neutron diffraction from 1.6 K to 940 K. It shows a very anisotropic expansion of 3.5 % along the a ‐axis up to 940 K, but along the c ‐axis a small expansion of 0.14 % up to 445 K is followed by a contraction about 0.4 % up to 940 K. On heating, the LT phase is observed up to the melting point at 962 K. A partial transformation to the HT phase takes place above 956 K. On cooling, the HT phase crystallises from the melt at 946 K and transforms to the LT phase at 930 K.