Synthesis, crystal and electronic structure, and transport properties of type-I semiclathrates Ge46–xPxSe8–yстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:A first clathrate compound with selenium guest atoms, [Ge46−xPx]Se8−y□y
(x = 15.4(1); y = 0−2.65; □ denotes a vacancy), was synthesized as a single-phase and
structurally characterized. It crystallizes in the space group Fm3̅ with the unit cell
parameter a varying from 20.310(2) to 20.406(2) Å and corresponding to a 2 × 2 × 2
supercell of a usual clathrate-I structure. The superstructure is formed due to the
symmetrical arrangement of the three-bonded framework atoms appearing as a result of
the framework transformation of the parent clathrate-I structure. Selenium guest atoms
occupy two types of polyhedral cages inside the positively charged framework; all selenium
atoms in the larger cages form a single covalent bond with the framework atoms, relating
the title compounds to a scanty family of semiclathrates. According to the measurements
of electrical resistivity and Seebeck coefficient, [Ge46−xPx]Se8−y□y is an n-type
semiconductor with Eg = 0.41 eV for x = 15.4(1) and y = 0; it demonstrates the
maximal thermoelectric power factor of 2.3 × 10−5 W K−2 m−1 at 660 K.