Suppression of structural instability in LaOBiS2-xSex by Se substitution

E. Paris, Y. Mizuguchi, T. Wakita, K. Terashima, T. Yokoya, Takashi Mizokawa, N. L. Saini

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    Isovalent substitution of S by Se in LaOBiS2-xSex has a substantial effect on its electronic structure and thermoelectric properties. To investigate the possible role of BiS2 structural instability, we have studied the local structure of LaOBiS2-xSex () using temperature dependent Bi L3-edge extended x-ray absorption fine structure measurements. The results reveal that the local structure of the two compounds is significantly different. The BiS2 sub-lattice is largely distorted in LaOBiS2 (x = 0.0), with two in-plane Bi-S1 distances separated by ∼0.4 Å instead LaOBiSSe (x = 1.0) showing much smaller local disorder with two in-plane Bi-Se distances in the plane being separated by ∼0.2 Å. Temperature dependent study shows that the two Bi-S1 distances are characterized by different bond strength in LaOBiS2 (x = 0.0) while it is similar for the Bi-Se distances in LaOBiSSe (x = 1.0). The out of plane Bi-S2 bond is harder in LaOBiSSe indicating that the structural instability of BiS2 layer has large effect on the out-of-plane atomic correlations. The results suggest that the local structure of LaOBiS2-xSex is an important factor to describe differing electronic and thermal transport of the two compounds.

    Original languageEnglish
    Article number455703
    JournalJournal of Physics Condensed Matter
    Issue number45
    Publication statusPublished - 2018 Oct 22


    • BiS-based materials
    • effect of substitution
    • local structure and bond characteristics
    • structural instability
    • temperature dependent EXAFS

    ASJC Scopus subject areas

    • Materials Science(all)
    • Condensed Matter Physics

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    Paris, E., Mizuguchi, Y., Wakita, T., Terashima, K., Yokoya, T., Mizokawa, T., & Saini, N. L. (2018). Suppression of structural instability in LaOBiS2-xSex by Se substitution. Journal of Physics Condensed Matter, 30(45), [455703].