Synthesis and characterization of a new family of layered Pb x Sn 4−x As 3 alloys

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 9; no. 20; pp. 6477 - 6483
• Main Authors: Koster, Karl G., Wang, Yaxian, Scudder, Michael R., Moore, Curtis E., Windl, Wolfgang, Goldberger, Joshua E.
• Format: Journal Article
• Language: English
• Published: 27.05.2021
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/D1TC00842K

Layered two-dimensional (2D) materials have attracted considerable interest for their exotic and anisotropic electronic behavior. One such material, Sn 4 As 3 , bears a resemblance in both structure and elemental composition to two other Sn- and As-containing layered materials that have recently demonstrated axis-dependent conduction polarity: NaSn 2 As 2 and NaSnAs. Here, a new family of Pb-alloyed Pb x Sn 4−x As 3 crystals was synthesized and the axis-dependent electronic and thermoelectric properties were evaluated. Up to one full equivalent of Pb could be alloyed into Pb x Sn 4−x As 3 (0 < x < 1.06) before phase separation occurred. We establish the structural changes and the trends in the Raman spectra with increasing Pb substitution. These materials all exhibit metallic temperature-dependent resistivities and positive thermopowers along the in-plane and cross-plane directions. The absence of axis-dependent conduction polarity in these SnAs-layered materials is consistent with theoretical predictions, and illustrates that precise control over the atomic and electronic structure and doping is essential for realizing this phenomenon in new materials.