Crystal Growth and Magnetic Measurements on Aligned Single Crystals of the Oxides Sr₃NiPtO₆ and Sr₃CuPtO₆

Crystals of Sr 3 NiPtO 6 and Sr 3 CuPtO 6 were grown from a K 2 CO 3 flux containing SrCO 3, NiO or CuO, and Pt metal powder, at 1150 °C. The structure of Sr 3 NiPtO 6 was solved by means of single-crystal X-ray diffraction analysis. The structure was refined in space group R 3̄ c, with a = 9.5832(1) Å and c = 11.1964(1) Å. Sr 3 CuPtO 6 and Sr 3 NiPtO 6 are structurally related to the parent compound, A 4 PtO 6 (A = Ca, Sr, Ba), and contain infinite chains of alternating, face-sharing PtO 6 octahedra and A‘O 6 (A‘ = Ni, Cu) trigonal prisms. Magnetic measurements were carried out on both samples using 3−5 mm long single crystals. Magnetic susceptibility studies on oriented single crystals of Sr 3 NiPtO 6 indicate the presence of Ni(II) ions with a large single-ion anisotropy ( D = 93.7(5) K, g ∥ = 2.143(6), and g ⊥ = 2.392(4)). In contrast, Sr 3 CuPtO 6 exhibits S = 1 / 2 Heisenberg linear chain antiferromagnetism with J / k = −24.7(1) K, J ‘/ k = −7.3(8) K, g ∥ = 2.127(6), and g ⊥ = 2.150(6).