Temperature-induced transitions between metastable phases of perovskite solid solutions
Variable temperature XRD studies are used to investigate the phase behavior of BiFe1-yScyO3 solid solutions. The observed metastable phases and the annealing-stimulated transitions be-tween them could be used to obtain new phase mixtures with desirable properties.
Perovskite multiferroics based on modified bismuth ferrite (BiFeO3) have recently attracted great interest due to their potential applications in the fields of mag-netism, photovoltaics and spintronics amongst others. Such materials are also of interest on a fundamental level and so modified versions of bismuth ferrite are explored as a means to enhance their properties and the potential number of applications.
Modified bismuth ferrite with Bi-site substitutions can generally be produced in bulk polycrystalline form following conventional synthesis procedures. In con-trast to this, to produce Fe-site substituted bismuth ferrites, high pressure synthesis must be employed which limits the quantity produced and also requires complex and expensive equipment.
Metastable perovskites with a 1:1 ratio of Fe3+ to a substituting B3+ cation are the most studied and sev-eral new phases have been found in their solid solu-tions. Competing phases form depending on the level of substitution and an antipolar Pnma phase, together with polar R3c and Ima2 phases have also been ob-served.
There have also been several studies on the (1-y)BiFeO3-yBiScO3 solid solutions, where the meta-stable antipolar Pnma phase is present between y = 0.30 and y = 0.60. The most studied solid solution within this series is that with y = 0.50, where there are two non-equivalent structures both in the Pnma space group which can be stabilized over the same tempera-ture range.
The results presented here are on the temperature behavior of metastable perovskite phases in the BiFe1-yScyO3 series studied by in-situ X-ray powder diffraction. The phase behavior is compared with other metastable perovskite solid solutions derived from BiFeO3.
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