Structural and magnetic studies of ABO4-type ruthenium and osmium oxides
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Date
2020-02-14
Journal Title
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Publisher
American Chemical Society
Abstract
Oxides of the form ABO4 with A = K, Rb, Cs and B = Ru and Os have been synthesized and characterized by diffraction and magnetic techniques. For A = K the oxides adopted the tetragonal (I41/a) scheelite structure. RbOsO4, which crystallizes as a scheelite at room temperature, underwent a continuous phase transition to I41/amd near 550 K. RbRuO4 and CsOsO4 were found to crystallize in the orthorhombic (Pnma) pseudoscheelite structure, and both displayed discontinuous phase transitions to I41/a at high temperatures. CsOsO4 was determined to undergo a phase transition to a P21/c structure below 140 K. CsRuO4 crystallizes with a baryte-type structure at room temperature. Upon heating CsRuO4 a first order phase transition to the scheelite structure in I41/a is observed at 400 K. A continuous phase transition is observed to P212121 below 140 K. DC magnetic susceptibility data is consistent with long-range antiferromagnetic ordering at low temperatures for all compounds except for CsOsO4, which is paramagnetic to 2 K. The effective magnetic moments are in agreement with the spin only values for an S = 1/2 quantum magnet. Effective magnetic moments calculated for Os compounds were lower than their Ru counterparts, reflective of an enhanced spin orbit coupling effect. A magnetic structure is proposed for RbRuO4 consisting of predominately antiferromagnetic (AFM) ordering along the 001 direction, with canting of spins in the 100 plane. A small ordered magnetic moment of 0.77 μB was determined. © 2020 American Chemical Society
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Keywords
Oxides, Cations, Specific heat, Quantum mechanics, Ruthenium, Osmium, Phase transformations, Diffraction, Antiferromagnetism, Magnetic moments
Citation
Injac, S., Yuen, A. K. L., Avdeev, M., Wang, C.-H., Turner, P., Brand, H. E. A., & Kennedy, B. J. (2020). Structural and magnetic studies of ABO4-type ruthenium and osmium oxides. Inorganic Chemistry, 59(5), 2791-2802. doi:10.1021/acs.inorgchem.9b03118