Tetrel-pnictides of rare-earth metals, R-T-Pn (T = Si, Ge; Pn = P, As), represent a scarcely investigated class of compound with complex structural chemistry and potentially interesting properties. The synthesis of these compounds is a challenge prompted us to look for new approach. Due to the volatility of phosphorus and arsenic, it is not possible to directly melt the reactants without strong depleting of sample with pnictogen due to evaporation. The typical synthesis routes in such cases are limited: molten metal flux (Bi, Sn, Pb etc.), molten salt flux (e.g. NaCl-KCl eutectic), gas transport reactions using a transport agent (I2 and NH4Cl) as well as high-temperature-high pressure reactions. Si and Ge are known to be relatively inert at the temperatures used in the synthesis (less than 1000 oC). As such, a synthesis using pre-reacted metal and silicon or germanium with phosphorus or arsenic becomes very appealing. Although such metal binaries typically have melting points above 1000 oC, they are known to decompose in the presence of a pnictogen-rich atmosphere, thereby forming binary and ternary phases. Therefore, careful optimization of the starting reactant ratios can yield phase-pure single-phase compounds, where excess P and As can be sublimed away from the phase of interest. Furthermore, this method can generate single crystals due to the P and As acting as transport agents in addition to being reactants. The structural chemistry, polymorphism, and properties of the family of R-Si-Pn compounds will be discussed.

Synthesis of ternary metal tetrel-pnictides using arc-melted precursors

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.