Structural and magnetic insights of the novel phosphate Ca2NiFe2(PO4)4

Abstract

One of the primary goals of scientists in the field of materials chemistry is to explore new functional materials, the discovery of new crystal structures and the understanding of their structure-properties relationship. This paper outlines the synthesis of a novel orthophosphate, Ca₂NiFe₂(PO₄)₄, in the single crystal and powder forms. The crystallographic analysis reveals that this newly synthesized phosphate exhibits an orthorhombic crystal lattice with the Pbca space group. The crystal structure is composed of PO₄ tetrahedra connected to Fe1O₆, Fe2O₅ and NiO₅ polyhedra through shared vertices. This interconnection forms a three-dimensional framework that encloses cavities housing Ca²⁺ cations. A sol-gel technique was employed to obtain the pure powder. The Rietveld refinement indicates an excellent correlation between the calculated and observed X-ray diffraction patterns. This material was further characterized structurally using infrared and Raman spectroscopy, and morphologically by scanning electron microscopy. The magnetic measurements revealed two magnetic transitions at T₁∼8.9 K and T₂∼16.5 K suggesting the presence of magnetic frustration with overall dominant antiferromagnetic behavior.