@article{b9f8dd0ab25e45a2b50c80a14a8cc57e,
title = "Using phase boundary mapping to resolve discrepancies in the Mg2Si-Mg2Sn miscibility gap",
abstract = "Mg2Si-Mg2Sn compositions within the Mg-Si-Sn materials system have potential as inexpensive, efficient thermoelectrics. These compositions lie specifically along the pseudobinary line with compositions of Mg2Si1−xSnx. The alloying and possible nanostructuring within the miscibility gap could further increase the thermoelectric figure of merit (zT) for these materials. However, the solubility limits of the miscibility gap differ greatly in the literature. Such a discrepancy could be a result of differing Mg-compositions due to excess magnesium added during sample annealing. To define these limits better and explain the change in proposed solubility limits based on magnesium content, the three-phase regions on either side of the pseudobinary phase region are phase boundary mapped and defect energy calculations are performed. This study presents a new understanding of the Mg-Si-Sn ternary phase diagram around the pseudobinary phase region. The solubility limits on either side of the pseudobinary should be essentially identical between the Mg-rich and Mg-poor three-phase regions unless the system temperature is brought above about 565 °C, at which eutectic liquid Mg0.9Sn0.1forms. This creates a second Mg-rich three-phase region which intersects the pseudobinary with a lower Sn solubility. Thus, samples prepared along the pseudobinary line are not well-defined thermodynamically when excess magnesium is added. Excess Mg can push the system into a new three phase region with Mg2Si1−xSnxcomposition different from that of the true miscibility gap. This understanding presents new guidelines for evaluating the miscibility gap and assists strategies for microstructure engineering and thermoelectric material processing.",
author = "Rachel Orenstein and Male, {James P.} and Michael Toriyama and Shashwat Anand and Snyder, {G. Jeffrey}",
note = "Funding Information: We acknowledge NSF DMREF award #1729487 and the support of award 70NANB19H005 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD). We thank Johannes de Boor and Mohammad Yasseri for helpful discussions. This work made use of the IMSERC X-Ray facility at Northwestern University, which has received support from the So and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-2025633), and Northwestern University. Additionally, this work made use of the EPIC facility of North-western University's NUANCE Center, supported by the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern's MRSEC program (NSF DMR-1720139). MT acknowledges support from the United States Department of Energy through the Computational Science Graduate Fellowship (DOE CSGF) under Grant Number DE-SC0020347. This research was supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at Northwestern University which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. Funding Information: We acknowledge NSF DMREF award #1729487 and the support of award 70NANB19H005 from U.S. Department of Commerce, National Institute of Standards and Technology as part of the Center for Hierarchical Materials Design (CHiMaD). We thank Johannes de Boor and Mohammad Yasseri for helpful discussions. This work made use of the IMSERC X-Ray facility at Northwestern University, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-2025633), and Northwestern University. Additionally, this work made use of the EPIC facility of Northwestern University's NUANCE Center, supported by the SHyNE Resource (NSF ECCS-2025633), the IIN, and Northwestern's MRSEC program (NSF DMR-1720139). MT acknowledges support from the United States Department of Energy through the Computational Science Graduate Fellowship (DOE CSGF) under Grant Number DE-SC0020347. This research was supported in part through the computational resources and staff contributions provided for the Quest high performance computing facility at Northwestern University which is jointly supported by the Office of the Provost, the Office for Research, and Northwestern University Information Technology. Publisher Copyright: {\textcopyright} The Royal Society of Chemistry 2021.",
year = "2021",
month = mar,
day = "21",
doi = "10.1039/d1ta00115a",
language = "English (US)",
volume = "9",
pages = "7208--7215",
journal = "Journal of Materials Chemistry A",
issn = "2050-7488",
publisher = "Royal Society of Chemistry",
number = "11",
}
