Highly frustrated Bi-Cr-Sb-O pyrochlore with spin-glass transition

The detailed study of magnetic properties, including dc and ac measurements, has been carried out on the Bi-Cr-Sb-O pyrochlore. The region of pyrochlore phase existence was determined and photocatalytic properties have been also studied. We revealed that the Bi-Cr-Sb-O pyrochlore phase occurs along Bi2−xCr1+xSbO7 section within the region x = 0.1-0.4. The Cr3+ ions oxidation state in Bi-Cr-Sb-O pyrochlore was confirmed by XANES spectra. The best Rietveld refinement results for Bi1.8Cr1.2SbO7 composition were achieved for the disordered structure model (space group Fd-3m). According to the magnetic data Bi1.8Cr1.2SbO7 is a highly frustrated pyrochlore with short-range antiferromagnetic exchange interactions between the nearest Cr3+ ions. At Tg = 4 К this compound undergoes spin-glass transition.