The biomineral phase of avian eggshell is characterized at the nanostructure scale and correlated with functional properties.

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Here we report on the investigation of structural, transport, and magnetic properties in double perovskite system, Sr2−xBaxFeMoO6(0⩽x⩽2). X-ray Diffraction analysis shows that the compounds form in single phase across the whole solid solution range. The Rietveld refinement of the x-ray data clearly indicates a structural transition from tetragonal (I4∕m) for x⩽0.6 to cubic (Fm3m) for x⩾1.6 with an orthorhombic (Fmmm) structure in the intermediate region (0.8⩽x⩽1.4). Magnetization studies show a regular increase in saturation magnetization from 2.0μB∕f.u.(x=0) to 3.0μB∕f.u.(x=2) with increasing Ba concentration. However, magnetization as well as electron-spin resonance (ESR) measurements confirmed a systematic decrease in the Curie temperatures from 420 K (x=0) to 310 K (x=2) with increasing x. Resistivity measurements carried out in zero magnetic field and for a field of 0.8 T reveal appreciably higher magnetoresistance for intermediate compositions in comparison to those at the ends.

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