Structure, site symmetry and spin-orbit coupled magnetism of a Ca12Al14O33 mayenite single crystal substituted with 0.26 at.% Ni

A Ca12Al14O33 mayenite single crystal with 0.26(1) at.% of the metals substituted by Ni was synthesized. Single crystal XRD confirms that about 10 at.% of Al and Ca partially occupy split crystallographic sites with lowered point symmetry. Ni K-edge XAS reveals that Ni is present as Ni2+ and substitutes Al on tetrahedral oxygen coordinated sites. UV-VIS analysis further points to the partial occupation of the trigonally distorted Al(1) and Al (1B) sites by Ni2+. In accordance with the results from the analytical methods, the magnetic model consists of Ni2+ with spin S = 1 on a trigonally distorted tetrahedral coordination site. The J-mulitplet splitting due to spin orbit coupling with a non-magnetic J = 0 ground state determines the characteristic thermomagnetic properties which show a maximum of the effective paramagnetic moment of 3.61(1) & mu;B at about 191 K and an uniaxial anisotropy (crystal field parameter B20 = 69.5(2) cm  1).

Automated summary

A Ca12Al14O33 mayenite single crystal with 0.26(1) at.% of Ni substitution was synthesized. XRD and XAS analysis confirmed the subsitution of Ni2+ for Al on tetrahedral oxygen coordinated sites. The magnetic model reveals the presence of Ni2+ ions with spin S = 1 on distorted tetrahedral coordination sites, determining the thermomagnetic properties and uniaxial anisotropy.