High Temperature Phase and Thermal Expansion of PrBr3
ated by BrϪ ions in the shape of a distorted bi-capped tri- and DSC measurements. The stability range of the high
angular prism. Those prisms share triangular faces and temperature phase was established for the first time.
form rods along the a-axis, as for the UCl3 type structure
where rods are aligned parallel to the c-axis. However, the
connectivity of the rods is different among these structures.
Acknowledgement
It occurs via two caps of the prisms in the PuBr3 type struc- Daniel Biner, DCB, is acknowledged for his help with the sample
preparation. We are grateful to the sample environment team of
Markus Zolliker, PSI, for their support during neutron experiments.
This work is based on experiments performed at the Swiss
spallation neutron source, SINQ, at the Paul Scherrer Institute.
ture but via three caps in the UCl3 type structure. That
small difference has remarkable consequences: UCl3 type
crystals show a hexagonal prismatic habitus and rugged
mechanical properties, whereas PuBr3 type crystals grow in
soft, well cleavable plates which easily split further into
bundles of fibres. These macroscopic properties are related
to the microscopic structure.
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Figure 10. Crystal structure of the high temperature modification
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In summary, as characterised by neutron diffraction, the
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Received: December 22, 2008
Published Online: March 17, 2009
Z. Anorg. Allg. Chem. 2009, 982Ϫ987
© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
987