Grain-by-Grain Compositional Variations and Interstitial Metals -  A New Route toward Achieving High Performance in Half-Heusler Thermoelectrics

Sonia A. Barczak,1 John E. Halpin,2 Jim Buckman,3 Rodolphe Decourt,4,5 Michael Pollet,4,5 Ronald I. Smith,6 Donald A. MacLaren,2*   and Jan-Willem G. Bos1*

1 Institute of Chemical Sciences and Centre for Advanced Energy Storage and Recovery, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
2 SUPA, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ, UK.
3 Institute of Petroleum Engineering, Heriot-Watt University, Edinburgh, EH14 4AS, UK.
4 CNRS, ICMCB, UPR 9048, F-33600 Pessac, France.
5 University of Bordeaux, ICMCB, UPR 9048, F-33600 Pessac, France.
6 ISIS Facility, Rutherford Appleton Laboratory, Harwell Oxford, Didcot OX11 0QX, UK.

*Email: j.w.g.bos@hw.ac.uk
*Email: dmaclaren@physics.org

Transmission Electron Microscopy data (figures 2 and 3)
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The raw data is recorded in Gatan's Digital Micrograph file format (details at the time of writing are advertised at: http://www.gatan.com/products/tem-analysis/gatan-microscopy-suite-software. This file format is readable by open source software package HyperSpy (http://hyperspy.org/). All data was acquired using a JEOL ARMcFEG instrument at 200kV, equipped with a Gatan Quantum electron spectrometer for EELS measurements and a Bruker XFlash EDS detector for x-ray mapping. Spectrum imaging is performed by first collecting a dark field 'survey image' then acquiring data within a sub-region indicated within the survey image. For the datasets used here, two EELS spectra (low-loss and core loss) and dark field images from two detectors ('Gatan DF' and 'Gatan HAADF') are recorded; the file names generally indicate the nature of each subset of the data. Note that metadata within the DM3 files may not be accurate, particularly user-inputted details of the sample and 'session info.' STEM data are generally collected using a 40 micron condenser aperture with 'spot size 7,8 or 9' JEOL ARM configuration and a camera length of 20mm.


(S)TEM and EELS data used to compile figs 2 and 3 are provided here. The data derives from a larger set of scans and images that were used to check for consistency and reproducibility but which are not included here.

Figure 2 – Images and spectral data are contained in the dataset 'HH1_*'
The spectral data comes from the files beginning ‘HH1_10_eelsgrainboundary_EELS Spectrum Image (*’

Figure 3 – Images, unprocessed diffraction pattern and spectral data are contained in the dataset 'HH2_*'
The spectral data comes from the files beginning
‘HH2_SI_EELS Spectrum Image (*’
The electron diffraction pattern comes from file ‘HH2_1_0017 (Inverted).dm3’

Dataset 'HH3_*' gives images and spectral data similar to those given in 'HH1_*', obtained on a different region.


Diffraction and Property Measurement Data
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The data underpinning the structural and thermoelectric property figures in the main paper (figures 1, 4 and 5) and supporting information are given figure by figure. These 'ogg' files can be opened using Origin (www.originlab.com). Scanning electron microscopy images and SEM-based elemental maps are also given as images.