Magnetic Frustration in a Zeolite

Zeolites are so well known in real-world applications and after decades of scientific study that they hardly need any introduction: their importance in chemistry cannot be overemphasized. Here, we add to the remarkable properties that they display by reporting our discovery that the simplest zeolite, sodalite, when doped with Cr³⁺ in the β-cage, is a frustrated magnet. Soft X-ray absorption spectroscopy and magnetic measurements reveal that the Cr present is Cr(III). Cr(III), with its isotropic 3d³ valence electron configuration, is well known as the basis for many geometrically frustrated magnets, but it is especially surprising that a material like the Ca₈Al₁₂Cr₂O₂₉ zeolite is a frustrated magnet. This finding illustrates the value of exploring the properties of even well-known material families.