Abstract
AbstractThe high-pressure structures of K-Ag alloys were examples of pressure-induced electron transfer from the electropositive potassium to the electronegative silver. We re-examined the crystal and electronic structures of KAg2, K2Ag, and K3Ag using powder X-ray diffraction and theoretical calculations. Our findings establish a connection between the morphologies of these three phases and the precursor face-centered cubic Ag. For K2Ag, we discovered a disordered structure that better matches the X-ray pattern. Valence electron density distributions obtained from the maximum entropy method, along with charge density calculations, provide a comprehensive understanding of the evolution of chemical bonding in these systems. It was found that K atoms share their valence electrons during alloy formation, contributing to K-Ag and Ag-Ag bonds in K2Ag and KAg2, while no Ag-Ag bonds are present in K3Ag. These results indicate the Zintl-Klemm model may be too simplistic to describe the structure and bonding in high-pressure binary intermetallic compounds.
Funder
National Research and Engineering Council of Canada
Publisher
Springer Science and Business Media LLC
Reference32 articles.
1. Atou, T., Hasegawa, M., Parker, L. J. & Badding, J. V. Unusual chemical behavior for potassium under pressure: potassium−silver compounds. J. Am. Chem. Soc. 118, 12104–12108 (1996).
2. Hasegawa, M., Atou, T. & Badding, J. V. High-pressure synthesis of an alkali metal–transition metal Laves phase: KAg2. J. Solid State Chem. 130, 311–315 (1997).
3. Sevov S. C. In intermetallic compounds: vol. 3, principles and practice (ed. Westbrook J. H. & Fleischer R. L.) Ch. 6 (John Wiley & Sons, Ltd., 2002).
4. Tse, J. S., Frapper, G., Ker, A., Rousseau, R. & Klug, D. D. Phase stability and electronic structure of K-Ag intermetallics at high pressure. Phys. Rev. Lett. 82, 4472–4475 (1997).
5. Nesper, R. The Zintl-Klemm concept – A historical survey. Z. Anorg. Allg. Chem. 640, 2639–2648 (2014).