Crystallization of New Samarium Polyborates

Rare earth borates are important due to their excellent
properties,
especially for optics. Here, we report the hydrothermal synthesis
and structural determination by single-crystal X-ray diffraction of
two new samarium polyborates with layered structures, being constituted
by hexaborate chains. These hexaborate chains are connected by samarium
polyhedra, forming dense sheets that further interact with each other
by hydrogen bonding via isolated boric acid between these sheets.
The third phase possesses a three-dimensional framework structure.
The thermal stability of selective samples has been studied. The crystallization
of samarium borate depends highly on the experimental conditions.
Three samarium polyborates have been crystallized in very similar
experimental conditions, clearly indicating that new lanthanide borate
compounds with tailored structures may be prepared in the future by
careful choice of physicochemical conditions.