KAgF3, K2AgF4 and K3Ag2F7: important steps towards a layered antiferromagnetic fluoroargentate(II),

AgIISO4: A Genuine Sulfate of Divalent Silver with Anomalously Strong One‐Dimensional Antiferromagnetic Interactions

“…Equipment used in the work is described elsewhere. [24] AgSO 4 [Eq. (1 a)]: A mixture of Ag(SbF 6 ) 2 , K 2 SO 4 , and solid HF at À196 8C was allowed to heat up inside a fluoropolymer reactor; a black precipitate formed immediately after the first droplets of liquid Bottom: Projection of spin density on the 011 plane as calculated using spin-polarized GGA + U method.…”

Silverland: the Realm of Compounds of Divalent Silver—and Why They are Interesting

“…Simultaneously, KAgF 3 was showed to be antiferromagnetic. The results of this research were published many years later [37], when a specialist in the Rietveld method, W. Łasocha, has proposed the models of the crystal structures of K 3 Ag 2 F 7 and KAgF 3 based on powder x-ray data which I obtained in the UK. Simultaneously, the crystal structure of K 2 AgF 4 was published coming from singlecrystal x-ray diffraction [37]; this structure was later shown by us to be incorrect (more on double perovskites below).…”

“…The 1D polymorph was not useful from the viewpoint of fluoroargentate(II)/oxocuprate(II) analogy, and our attention has turned to KAgF 3 . Our previous results have indicated that it adopts a distorted quasi-3D perovskite lattice, was antiferromagnetic, and exhibited huge spin polarization at F sites [37]. However, its preparation method suffered from the formation of an undesirable FM K 2 AgF 4 minority phase (due to an excess of KF formed in situ just like in early experiments described in Section 8); this affected the precise determination of magnetic susceptibility in the high-T regime, where a constant Pauli-paramagnet-like dependence was previously observed [40].…”

α-K2AgF4: Ferromagnetism induced by the weak superexchange of different eg orbitals from the nearest neighbor Ag ions

“…La 2 CuO 4 is an antiferromagnetic (AFM) insulator. However, in contrast to La 2 CuO 4 , α-K 2 AgF 4 was reported as a ferromagnetic (FM) insulator with T C ∼ 26 K. 3,4 In general, magnetic ions are often antiferromagnetically coupled through superexchange interaction in insulators, while ferromagnetically coupled through Stoner itinerant electrons band model in metal. Therefore, FM in insulator is abnormal in transition metal compounds.…”

“…A new layered perovskite-related fluoroargentates(II), K 2 AgF 4 , has been synthesized by Z. Mazej et al 3,4 Here after, as described in Ref. 4, we will refer to the quasi-two-dimensional polymorph of K 2 AgF 4 as α-K 2 AgF 4 , which is isostructural to the parent compound of high-T C cuprate La 2 CuO 4 .…”