Crystal Cluster Growth and Physical Properties of
the EuSbSe<sub>3</sub> and EuBiSe<sub>3</sub> Phases
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Abstract
Syntheses of europium metal, selenium
powder, and the Sb<sub>2</sub>Se<sub>3</sub>/Bi<sub>2</sub>Se<sub>3</sub> binaries were observed to produce crystal clusters of the
EuSbSe<sub>3</sub> and EuBiSe<sub>3</sub> phases. These phases crystallize
with the <i>P</i>2<sub>1</sub>2<sub>1</sub>2<sub>1</sub> space group and can be easily identified based on their growth habits,
forming large clusters of needles. Previous literature suggested that
their structure is charge-balanced with all europium atoms in the
divalent state and one-quarter of the selenium atoms forming trimers.
Physical property measurements on a pure sample of EuSbSe<sub>3</sub> revealed typical Arrhenius-type electrical resistivity, being approximately
3 orders of magnitude too large for thermoelectric applications. Electronic
structure calculations indicated that both EuSbSe<sub>3</sub> and
EuBiSe<sub>3</sub> are narrow-band-gap semiconductors, in good agreement
with the electrical resistivity data. The valence and conduction band
states near the Fermi level are dominated by the Sb/Bi and Se p states,
as expected given their small difference in electronegativity
