Structural modifications of disordered YMn1−xInxO3 solid solutions evidenced by infrared and Raman spectroscopies

Polycrystalline YMn1−xInxO3 compounds were obtained by solid state reaction and found to present a blue color for high substitution rate. X-ray diffraction analyses reveal the formation of solid solutions and the increase of cell parameters following Vegard's law. Far infrared reflectivity and Raman scattering spectra show the presence of random disorder and structural modifications without phase transition. A detailed analysis of some phonon modes allows to explain the structural changes upon doping. It was found that monocaping YO7 antiprisms are almost unaffected by substitution. However, results reveal the existence of two different MO5 (M = In, Mn) trigonal bipyramids. Their apical Mn–O distances are shorter than In–O bonds and both distances increase with the substitution rate, which is consistent with the evolution of the cell parameters.

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► Hexagonal YMn1−xInxO3 single phase powders were successfully synthesized up to x = 0.90.
► Far-infrared and Raman spectroscopies investigations of local changes of the structure.
► Existence of strong static random disorder.
► Existence of two different MO5 (M = Mn, In) trigonal bipyramids.
► The increase of c parameter is related to an elongation of MO5 cages.