Clathrate XI K58Zn122Sb207: A New Branch on the Clathrate Family Tree

The compositional screening of K‐Zn‐Sb ternary system aided by machine learning, rapid exploratory synthesis using KH salt‐like precursor and in situ powder X‐ray diffraction yielded a novel clathrate type XI K58Zn122Sb207. This clathrate consists of a 3D Zn‐Sb framework hosting K+ ions inside polyh...

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Bibliographic Details
Published in:Angewandte Chemie 2021-01, Vol.133 (1), p.419-427
Main Authors: Cox, Tori, Gvozdetskyi, Volodymyr, Bertolami, Mark, Lee, Shannon, Shipley, Kristian, Lebedev, Oleg I., Zaikina, Julia V.
Format: Article
Language:English
Subjects:
antimony
Antiphase boundaries
Cages
Cations
Chemistry
clathrate
Clathrates
Crystal defects
crystal structure
Family trees
Learning algorithms
Machine learning
Scanning transmission electron microscopy
Single crystals
Stacking faults
Synchrotrons
Ternary systems
Thermal conductivity
thermoelectric
Transmission electron microscopy
Twinning
X-ray diffraction
Zinc
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Summary:The compositional screening of K‐Zn‐Sb ternary system aided by machine learning, rapid exploratory synthesis using KH salt‐like precursor and in situ powder X‐ray diffraction yielded a novel clathrate type XI K58Zn122Sb207. This clathrate consists of a 3D Zn‐Sb framework hosting K+ ions inside polyhedral cages, some of which are reminiscent of known clathrate types while others are unique to this structure type. The complex non‐centrosymmetric structure in the tetragonal space group I4‾2m was solved by means of single crystal X‐ray diffraction as a 6‐component twin due to pseudocubic symmetry and further confirmed by high‐resolution synchrotron powder X‐ray diffraction and state‐of‐the‐art scanning transmission electron microscopy. The electron‐precise composition of this clathrate yields narrow‐gap p‐type semiconductor with extraordinarily low thermal conductivity due to displacement or “rattling” of K cations inside oversized cages and as well as to twinning, stacking faults and antiphase boundary defects. Unconventional synthesis guided by machine‐learning and in situ X‐ray diffraction allowed the new type of inorganic clathrate K58Zn122Sb207 to be synthesized. This compound is a rare case of an inorganic clathrate which does not contain Group 14 elements, as well as being a structure not seen previously among clathrates. X‐ray diffraction and STEM reveal a complex structure with promising thermoelectric properties.
ISSN:0044-8249
1521-3757
DOI:10.1002/ange.202011120