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Updated: Oct 4, 2025
Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
Models of Ni- and Co-ion occupation in LiNi0.5Co0.5PO4orthophosphate and its magnetic structure
M A Semkin1,2, N V Urusova2,3, A Hoser4
1M N Miheev Institute of Metal Physics, Ural Branch, Russian Academy of Sciences, 18 S Kovalevskaya St., Ekaterinburg, Russia.
Abstract:
The neutron diffraction, magnetic and heat capacity measurements have been carried out to study the polycrystalline sample LiNi0.5Co0.5PO4prepared by the glycerol-nitrate synthesis method. Models of Ni- and Co-ion occupation the 4coctahedral position in a crystal structure LiNi0.5Co0.5PO4are calculated for a paramagnetic state. The best model is the Ni- and Co-ions occupy the 4csite inPnmapatent space-group in sequence Ni-Co-Ni-Co or Co-Ni-Co-Ni. It is shown that nickel ions formabplanes alternating with the planes of cobalt ions in the direction of theccrystallographic axis. At 7 K, an average magnetic moment of 3d-ions is equal to 1.90 (9)μB. The moments are ordering antiferromagnetically and parallel to thebcplane decreasing to zero at 15 K. In the high-spin state a temperature dependence of the Ni2+/Co2+ion-magnetic moment is well described within the 2D Ising model with order parameterβ= 0.198 and Néel temperatureTN= 14.1 (1) K, obtained from heat capacity data. This temperature agrees well withTcr= 14.3 (2) K, determined with magnetic measurement. Maybe the short-range magnetic order exists in LiNi0.5Co0.5PO4over temperature region (14-16) K, that is confirmed by the maximum on a temperature dependence of the magnetization at 16.1 (5) K.
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