A novel phosphate with CoII square planar coordination, BaCo0.5Fe(PO4)2: structural and magnetic features
Fouad Alloun1, Mohammed Hadouchi1, Sirine El Arni1
1Laboratoire de Chimie Appliquée des Matériaux, Centre des Sciences des Matériaux, Faculty of Science, Mohammed V University in Rabat, Avenue Ibn Battouta, BP 1014, Rabat, Morocco. m.hadouchi@um5r.ac.ma.
Abstract:
A novel phosphate containing barium, cobalt, and iron was synthesized in single-crystal and polycrystalline forms. Single crystal-based X-ray measurements revealed that it crystallizes in the monoclinic system with the P21/c space group. The structure is made up of linkages between FeO6 octahedra, CoO4 square planar units, CoO5 square pyramidal units, and PO4 tetrahedra through edges and/or vertices. The interconnection of these polyhedra leads to a three-dimensional framework with tunnels along the a-axis where the Ba2+ cations are located. The polycrystalline form was prepared via the sol-gel method and its XRD pattern was refined by the Le Bail method. Morphological and elemental mapping analyses of this phosphate were performed by scanning electron microscopy. In addition, infrared and Raman spectroscopy provided more insights into chemical bonding. The magnetic behavior was antiferromagnetic below TN ∼ 20 K. Optical measurements revealed a direct bandgap with an energy Eg of 2.83 eV.
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