Synthesis, Crystal Structure, and Physical Properties of the New Chain Alkalioxocuprate K₃Cu₂O₄

Abstract

Single crystals of K 3 Cu 2 O 4 were prepared by the azide/nitrate route from respective stoichiometric mixtures of KN 3 , KNO 3 and CuO, at 923 K, whereas powder samples were synthesised by solid state reaction of K 2 O, KCuO 2 and CuO, sealed in gold ampoules and treated at 723 K. According to the single crystal structure analysis (Cmcm, Z = 4, a = 6.1234(1), b = 8.9826(2), c = 10.8620(2) Å, R 1 = 0.044, R 2 = 0.107), the main structural feature are undulating 1 ∞ CuO 2 chains built up from planar, edge sharing CuO 4 square units. From an

K4Ni3O6 and KNa2Ni2O4, New Quasi One‐Dimensional ­Oxonickelates(II, III)

“…Induced by the respective d 8 , d 9 , and d 7 (low spin) electron configurations, both, nickel and copper in oxidation states of 2+ and 3+, show a distinct inclination for square‐planar coordination arrangements, in particular in cation rich oxides. This is reflected among others by pairs of isostructural alkali oxometalates like Li 2 CuO 2 1–Li 2 NiO 2 ,2 or K 3 Cu 2 O 4 3–K 3 Ni 2 O 4 4. Interestingly, the decoration with electron spins of the underlying oxometalate chains of edge sharing squares is different, whereas the charge distribution patterns are identical.…”

“…With the azide/nitrate route11–13 we have developed a procedure, which enables to fulfill these quite demanding requirements. Along this approach, we were able to synthesize two families of low‐dimensional, intrinsically doped oxocuprates(II, III)3,9,10 and oxomanganates(II, III),14–16 which are rich in unique physical phenomena. The quasi‐one‐dimensional cuprates(II, III) have attracted attention since they are regarded model systems for the cuprate superconductors.…”