materials Review Zintl Phases as Reactive Precursors for Synthesis of Novel Silicon and Germanium-Based Materials Matt Beekman 1,* , Susan M. Kauzlarich 2 , Luke Doherty 1,3 and George S. Nolas 4 1 Department of Physics, California Polytechnic State University, San Luis Obispo, CA 93407, USA;
[email protected] 2 Department of Chemistry, University of California, Davis, CA 95616, USA;
[email protected] 3 Department of Materials Engineering, California Polytechnic State University, San Luis Obispo, CA 93407, USA 4 Department of Physics, University of South Florida, Tampa, FL 33620, USA;
[email protected] * Correspondence:
[email protected] Received: 5 February 2019; Accepted: 27 March 2019; Published: 8 April 2019 Abstract: Recent experimental and theoretical work has demonstrated significant potential to tune the properties of silicon and germanium by adjusting the mesostructure, nanostructure, and/or crystalline structure of these group 14 elements. Despite the promise to achieve enhanced functionality with these already technologically important elements, a significant challenge lies in the identification of effective synthetic approaches that can access metastable silicon and germanium-based extended solids with a particular crystal structure or specific nano/meso-structured features. In this context, the class of intermetallic compounds known as Zintl phases has provided a platform for discovery of novel silicon and germanium-based materials. This review highlights some of the ways in which silicon and germanium-based Zintl phases have been utilized as precursors in innovative approaches to synthesize new crystalline modifications, nanoparticles, nanosheets, and mesostructured and nanoporous extended solids with properties that can be very different from the ground states of the elements.