Syntheses and structures of BaPrxBi1−xO3 perovskites

The perovskite-type BaPr0.75Bi0.25O2.69 and BaPrxBi1−xO3 (x=0.025x=0.025, 0.10, 0.25, 0.33, 0.5, 0.67, 0.75) solid solutions containing mixed valent praseodymium and bismuth ions have been synthesized via a two-stage synthetic procedure. The crystal structure of BaPr0.67Bi0.33O3 has been refined from X-ray data by the Rietveld method and was found to be orthorhombic (Pnma) with a=6.1650(2)Å, b=8.7069(2)Å, c=6.2014(1)Å. The Rietveld refinement of BaPr0.75Bi0.25O3 has revealed an orthorhombic cell (Pnma) with a=6.1713(3)Å, b=8.7145(3)Å, c=6.2106(2)Å. Magnetic transitions at 4.4 K and 9.1 K in a low magnetic field (0.001 T) were observed for BaPr0.75Bi0.25O2.69 and BaPr0.75Bi0.25O3 respectively. Divergences between the ZFC and FC measurements of magnetic susceptibility were observed for BaPr0.025Bi0.975O3 and BaPr0.25Bi0.75O3. Two regions of different valence situations in BaPrxBi1−xO3 were established. Interestingly, the readiness of praseodymium to adopt the tetravalent state increases with growing x.

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