New synthesized bismuth-based pyrochlore compounds Bi1.5-xMxSb1.5-xM'xZnO7 (M= Fe; M'=Fe, Cr) (x=0.0; 0.10; 0.15): A structural study.

Abstract

Abstract New limited pyrochlore solid solutions of formula Bi1.5-xMxSb1.5-xM'xZnO7 (M= Fe; M'=Fe, Cr) (x=0; 0.10; 0.15) are prepared from simple oxides at 1080°C by using the ceramic method. All the crystal phases are indexed in the cubic system (space group; No.227). Rietveld refinement method of the Bi1.5Sb1.5ZnO7 (x=0) compounds using powder XRD analysis confirms an overall A2B2O7 cubic pyrochlore structure according to B i 1 . 5 3 + Z n 0 . 5 2 + S b 1 . 5 5 + Z n 0 . 5 2 + O 7 formula with 10.44425(3) Å and F d 3 ¯ m space group. The substitution of Bi(III) and Sb(V) by Fe(III) and Cr(III) in the Bi1.5Sb1.5ZnO7 phase shows the appearance of solid solutions limited to x=0.15. The variation of the cell’s parameter is recorded to the element’s ionic radii. The paramagnetic character is observed in all substituted compounds. The measurements of the electrical conductivity as a function of the temperature, make evidence of the semi-conductive property. Whilst, the magnetic susceptibility satisfies the modified Curie Weiss (CW) and shows the magnetic behavior due to the magnetic moments of the iron and chromium ions being involved in the synthesis of the compounds. Besides, the UV-Visible reflectance displays light absorption in the visible domain.

Keywords

• Pyrochlore
• Oxides
• Solid Solution
• Magnetic susceptibility
• Electric Conductivity