A comprehensive examination of the local- and long-range structure of Sb₆O₁₃ pyrochlore oxide

The crystal structure of the Sb₆O₁₃ oxide, exhibiting a defect pyrochlore crystal structure with atomic vacancies, has been studied using a complete set of state-of-the-art techniques. The degree of antimony disproportionation in Sb³⁺ and Sb⁵⁺ valence states has been directly determined around 36% and 64%, respectively, using X-ray absorption near edge structure (XANES). These findings are in excellent agreement with our Rietveld analysis of synchrotron X-ray (SXRD) and neutron powder diffraction (NPD) results. Moreover, the highly distorted Sb³⁺ coordination due to its lone electron pair has been critically revisited. The bonding distances and coordination of Sb³⁺ and Sb⁵⁺ species closely agree with an extensive dynamic and crystallographic determination using the Extended X-ray Absorption Fine Structure (EXAFS) technique. Most importantly, the specific local disorder of the two distinctive Sb ions has been crosschecked monitoring their unusual Debye-Waller factors.