Evidence for an Antiferromagnetic Transition in a Zeolite-Supported Cubic Lattice of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="italic">F</mml:mi></mml:math>Centers

Abstract

Evidence for a bcc lattice of $F$ centers in sodium-electro-sodalite (SES), synthesized by exposing dehydrated sodalite to sodium vapor, is presented. A high electron spin density in SES produces isotropic contact shifts in nuclear magnetic resonance (NMR) spectra of the framework nuclei whose magnitude is a discrete function of local electron density. Strong exchange coupling between unpaired electrons gives rise to an antiferromagnetic phase transition in SES at ${T}_{N}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}48\ifmmode\pm\else\textpm\fi{}2\mathrm{K}$, providing the first example of an $s\ensuremath{-}\mathrm{electron}$ antiferromagnet.