Neutron diffraction study of the influence of structural disorder on the magnetic properties of Sr(2)FeMO(6) (M=Ta, Sb)

Journal article

The crystal structure of the perovskite Sr2FeTaO6 has been refined by simultaneous analysis of X-ray and neutron powder diffraction data collected at 280 K; space group Pbnm, a = 5.6204(3), b = 5.6161(3), c = 7.9266(3) Å. The structure is of the GdFeO3 type, with a disordered distribution of Fe and Ta over the six-coordinate cation sites. The structure of Sr2FeSbO6 has been refined in a similar manner; space group P21/n, a = 5.6132(5), b = 5.5973(5), c = 7.9036(7) Å, β = 90.01(1)°. The two crystallographically distinct six-coordinate sites in Sr2FeSbO6 are occupied in a partially ordered manner [0.795(6):0.205(6)] by Fe and Sb atoms. Neutron diffraction data collected from Sr2FeTaO6 at 1.5 K show no evidence of long-range magnetic ordering and, in the light of previous susceptibility and Mössbauer measurements, it is concluded that Sr2FeTaO6 is a spin glass below 23 K. Neutron diffraction data collected from Sr2FeSbO6 at 1.5 K include magnetic Bragg peaks characteristic of a type I magnetic structure with an average ordered moment of 3.06(9) μB per Fe atom on the Fe-dominated octahedral site, and no significant ordered moment on the second site. The magnetic Bragg scattering decreases to zero in the temperature interval 1.5 ≤ T/K ≤ 37(2). It is concluded that the partial cation ordering leads to the coexistence of a magnetically ordered spin system and a spin-glass system.

Authors: Cussen, E; Vente, J; Battle, P; Gibb, T

• Publication status: Published
• Journal: JOURNAL OF MATERIALS CHEMISTRY
• Volume: 7
• Issue: 3
• Pages: 459-463
• Publication date: 1997-03-01
• DOI: 10.1039/a607083c
• EISSN: 1364-5501
• ISSN: 0959-9428
• Language: English