• Ovchinnikov, Alexander
• Samarakoon, S. M. Gayomi K.
• Bobev, Svilen

Abstract

<jats:title>Abstract</jats:title><jats:p>The binary Zintl phase Ba<jats:sub>16</jats:sub>Sb<jats:sub>11</jats:sub> has been synthesized and structurally characterized. Detailed studies via single‐crystal X‐ray diffraction methods indicate that although Ba<jats:sub>16</jats:sub>Sb<jats:sub>11</jats:sub> appears to crystallize in the tetragonal Ca<jats:sub>16</jats:sub>Sb<jats:sub>11</jats:sub> structure type (space group <jats:italic>P</jats:italic><jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/zaac202300148-math-0001.png" xlink:title="urn:x-wiley:00442313:media:zaac202300148:zaac202300148-math-0001" /> 2<jats:sub>1</jats:sub><jats:italic>m with a</jats:italic>=13.5647(9) Å, <jats:italic>c</jats:italic>=12.4124(12) Å, <jats:italic>Z</jats:italic>=2, <jats:italic>R</jats:italic><jats:sub>1</jats:sub>=3.14 %; <jats:italic>wR</jats:italic><jats:sub>2</jats:sub>=4.77 %), there exists an extensive structural disorder. Some Ba<jats:sub>16</jats:sub>Sb<jats:sub>11</jats:sub> crystals were found to be monoclinic and the structure was solved and refined in space group <jats:italic>P</jats:italic>2<jats:sub>1</jats:sub> (<jats:italic>a</jats:italic>=18.3929(12) Å, <jats:italic>b</jats:italic>=13.5233(8) Å, <jats:italic>c</jats:italic>=18.3978(12) Å, <jats:italic>β</jats:italic>=94.6600(10)°; <jats:italic>Z</jats:italic>=4, <jats:italic>R</jats:italic><jats:sub>1</jats:sub>=5.84 %; <jats:italic>wR</jats:italic><jats:sub>2</jats:sub>=9.58 %). The latter corresponds to a 2‐fold superstructure of the tetragonal one, which provides a disorder‐free structural model. In both descriptions, the disordered tetragonal and the ordered monoclinic superstructure, the basic building units that make up the structure of this Ba‐rich compound are pairs of face‐shared square antiprisms of Ba atoms, which are centered by Sb atoms. The dimerized antiprisms are linked into parallel chains via square prisms of Ba atoms, which are also centered by Sb atoms. The Zintl concept can be applied in a straightforward manner and as result, the structure of Ba<jats:sub>32</jats:sub>Sb<jats:sub>22</jats:sub> (=2×Ba<jats:sub>16</jats:sub>Sb<jats:sub>11</jats:sub>) can be rationalized as (Ba<jats:sup>2+</jats:sup>)<jats:sub>32</jats:sub>(Sb<jats:sup>3−</jats:sup>)<jats:sub>20</jats:sub>[Sb<jats:sub>2</jats:sub>]<jats:sup>4−</jats:sup>. The partitioning of the valence electrons is done taking into an account the homoatomic Sb−Sb contacts (<jats:italic>d</jats:italic>=3.01 Å), which can be clearly distinguished in the lower symmetry space group. Electronic structure calculations of Ba<jats:sub>16</jats:sub>Sb<jats:sub>11</jats:sub> are in good accordance with the Zintl rationalization and predict a semiconductor with a band gap of 0.77 eV.</jats:p>

Topics

• impedance spectroscopy
• compound
• phase
• semiconductor
• space group
• diffraction method