Synthesis, structural characterization and magnetic behavior of a novel phosphate: K4(Co0.25Fe0.75)4(PO4)5

The search for new materials and the understanding of their structure-property relationship has been the subject of many studies. In this context, a new phosphate K4(Co0.25Fe0.75)4(PO4)5 is synthesized in single crystal and powder forms. The Structural, vibrational characterization, and magnetic properties are investigated. The title phosphate crystallizes in the tetragonal system with the space group P4‾21c and unit cell parameters a = 9.7141 (2) Å and c = 9.4657 (3) Å. The structure consists of the association of (Fe/Co)O5 trigonal bipyramids and PO4 tetrahedra resulting in an open three-dimensional structure with elliptical channels running along the [001] direction, where the cations K+ are situated. X-ray diffraction and SEM-EDS analysis were used to analyze the purity, morphology and chemical composition of the synthesized powder. Infrared and Raman spectroscopy confirms the presence of vibrational modes of PO4 tetrahedra. The magnetic susceptibility measurement indicates the appearance of ferrimagnetic behavior at Tc ∼17 K. [Display omitted] •K4CoFe3(PO4)5 is elaborated in both single crystal and polycrystalline forms.•The structural investigation shows a tunnels-type crystal framework.•Ferrimagnetic behavior is reported below Tc ∼17 K.