Structural, optical and magnetic proprieties of a new pyrochlore type structure (Bi1.44□0.24Fe0.32)(Sb1.36Fe0.64)O7 compound derived from the Bi1.56 – x/8Sb1.48-x/8Co0.96-xFexO7 (0 ≤ x ≤ 0.96) solid solution

A new pyrochlore solid solution with formula Bi 1.56 – x/8 Sb 1.48-x/8 Co 0.96-x Fe x O 7 (0 ≤ x ≤ 0.96) was synthesized by the ceramic method at high temperature. The cell parameter decreased gradually with increasing iron content. The structure refinement by the Rietveld method showed for x = 0.96 a new compound with formula Bi 1.44 Sb 1.36 Fe 0.96 O 7 witch crystallizing in the Fd 3 ̅ m space group. The average crystallite size calculated by the Scherrer equation varied between 62 and 69 nm. The scanning electron microscopy (SEM) analysis revealed a granular surface. The average particle size was estimated to be between 700 and 1072 nm. The magnetic susceptibility of Bi 1.44 Sb 1.36 Fe 0.96 O 7 compound, measured from 5 K to 400 K, shows a Curie–Weiss temperature θ CW of approximately −206.74. This value indicates significant antiferromagnetic cooperative interactions. The observed effective magnetic moment of 5.99 μB , indicated the spin-only values expected for Fe 3 + (i.e 3d 5 , high spin t 2 g 3 e g 2 ) . The UV-Vis diffuse reflectance spectroscopy (UV/DRS) indicated an absorption in the visible range, with an optical band gap energy (Eg) between 2.53 and 2.12 eV. • New pyrochlore solid solution structure with formula Bi 1.56 – x/8 Sb 1.48-x/8 Co 0.96-x Fe x O 7 was synthetised. • New iron-based pyrochlore-type compound of formula Bi 1.44 Sb 1.36 Fe 0.96 O 7 was charaterized by Rietveld structure refinement. • The Bi 1.44 Sb 1.36 Fe 0.96 O 7 compound shows a significant antiferromagnetic cooperative interactions and visible absorption.