ChemInform Abstract: Novel Mixed Cobalt/Chromium Phosphate NaCoCr₂(PO₄)₃ Showing Spin‐Flop Transition.

Abstract

Transition. -The new title compound is prepared by solid state reaction of a stoichiometric mixture of Na 2CO3, Co(NO3)2, Cr(NO3)3, and (NH4)H2PO4 (Pt crucible, 1423 K, 48 h). NaCoCr2(PO4)3 is characterized by powder XRD, and magnetic and specific heat measurements. It crystallizes in the orthorhombic space group Imma with Z = 4. The framework consists of PO 4 tetrahedra, CrO6 octahedra, and (0.5Cr + 0.5Co)2O10 binuclear units of edge-sharing (0.5Cr + 0.5Co)O 6 octahedra. Na + ions are located within intersecting tunnels delimited by the framework. The compound shows a magnetic phase transition from para-to antiferromagnetic behavior at about 32 K. A spin-flop transition is likely due to the competition within the (0.5Cr + 0.5Co)2O10 bioctahedral units between Co 2+ -O(2p)-Cr 3+ ferromagnetic 90 superexchange interactions and Cr 3+ -O(2p)-Cr 3+ antiferromagnetic 90 superexchange interactions, and mediated by direct exchange. -(SOUIWA, K.; CHENNABASAPPA, M.; DECOURT, R.; BEN AMARA, M.; HIDOURI*, M.; TOULEMONDE, O.; Inorg. Chem. 54 (2015) 15, 7345-7352, http://dx.doi.org/10.1021/acs.inorgchem.5b00776 ; Fac. Sci., Univ. Monastir, 5019 Monastir, Tunisia; Eng.) -W. Pewestorf 41-012