Precursor Routes to Complex Ternary Intermetallics: Single-Crystal and Microcrystalline Preparation of Clathrate-I Na8Al8Si38 from NaSi + NaAlSi

Yongkwan Dong; Ping Chai; Matt Beekman; Xiaoyu Zeng; Terry M Tritt; George S Nolas

doi:10.1021/acs.inorgchem.5b00348

Precursor Routes to Complex Ternary Intermetallics: Single-Crystal and Microcrystalline Preparation of Clathrate-I Na8Al8Si38 from NaSi + NaAlSi

Inorg Chem. 2015 Jun 1;54(11):5316-21. doi: 10.1021/acs.inorgchem.5b00348. Epub 2015 May 18.

Authors

Yongkwan Dong¹, Ping Chai¹, Matt Beekman², Xiaoyu Zeng³, Terry M Tritt³, George S Nolas¹

Affiliations

¹ †Department of Physics, University of South Florida, Tampa, Florida 33620, United States.
² ‡Department of Natural Sciences, Oregon Institute of Technology, Klamath Falls, Oregon 97601, United States.
³ §Department of Physics and Astronomy, Kinard Laboratory, Clemson University, Clemson, South Carolina 29634, United States.

PMID: 25985168
DOI: 10.1021/acs.inorgchem.5b00348

Abstract

Single crystals of the ternary clathrate-I Na8Al8Si38 were synthesized by kinetically controlled thermal decomposition (KCTD), and microcrystalline Na8Al8Si38 was synthesized by spark plasma sintering (SPS) using a NaSi + NaAlSi mixture as the precursor. Na8AlxSi46-x compositions with x ≤ 8 were also synthesized by SPS from precursor mixtures of different ratios. The crystal structure of Na8Al8Si38 was investigated using both Rietveld and single-crystal refinements. Temperature-dependent transport and UV/vis measurements were employed in the characterization of Na8Al8Si38, with diffuse-reflectance measurement indicating an indirect optical gap of 0.64 eV. Our results indicate that, when more than one precursor is used, both SPS and KCTD are effective methods for the synthesis of multinary inorganic phases that are not easily accessible by traditional solid-state synthesis or crystal growth techniques.