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Title: Structure and transport properties of dense polycrystalline clathrate-II (K,Ba) 16(Ga,Sn) 136 synthesized by a new approach employing SPS

Tin clathrate-II framework-substituted compositions are of current interest as potential thermoelectric materials for medium-temperature applications. A review of the literature reveals different compositions reported with varying physical properties, which depend strongly on the exact composition as well as the processing conditions. We therefore initiated an approach whereby single crystals of two different (K,Ba) 16(Ga,Sn) 136 compositions were first obtained, followed by grinding of the crystals into fine powder for low temperature spark plasma sintering consolidation into dense polycrystalline solids and subsequent high temperature transport measurements. Powder X-ray refinement results indicate that the hexakaidecahedra are empty, K and Ba occupying only the decahedra. Their electrical properties depend on composition and have very low thermal conductivities. As a result, the structural and transport properties of these materials are compared to that of other Sn clathrate-II compositions.
Authors:
 [1] ;  [2] ;  [2] ;  [1] ; ORCiD logo [1] ;  [1]
  1. Univ. of South Florida, Tampa, FL (United States)
  2. Clemson Univ., Clemson, SC (United States)
Publication Date:
Grant/Contract Number:
FG02-04ER46145
Type:
Accepted Manuscript
Journal Name:
Materials
Additional Journal Information:
Journal Volume: 9; Journal Issue: 9; Journal ID: ISSN 1996-1944
Publisher:
MDPI
Research Org:
Univ. of South Florida, Tampa, FL (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; clathrate; SPS processing; thermoelectrics
OSTI Identifier:
1361383