Condensed Matter (Jul 2023)

Tensile Microstrain Fluctuations in the BaPbO Units in Superconducting BaPb<sub>1−x</sub>Bi<sub>x</sub>O<sub>3</sub> by Scanning Dispersive Micro-XANES

  • Ruben Albertini,
  • Salvatore Macis,
  • Andrei A. Ivanov,
  • Alexey P. Menushenkov,
  • Alessandro Puri,
  • Virginia Monteseguro,
  • Boby Joseph,
  • Wei Xu,
  • Augusto Marcelli,
  • Paula Giraldo-Gallo,
  • Ian Randal Fisher,
  • Antonio Bianconi,
  • Gaetano Campi

DOI
https://doi.org/10.3390/condmat8030057
Journal volume & issue
Vol. 8, no. 3
p. 57

Abstract

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BaPb1−xBixO3 (BPBO) bismuthate, showing high TC superconductivity for 0.05 3] centered nanoscale units (BBO) coexist with BaPbO3 centered (BPO) units in the BPBO perovskite; therefore, we expect a tensile microstrain in BPO units due the misfit strain between the two different lattices. Here, we report the measurement of the spatial micro-fluctuations of the local tensile microstrain ε in the BaPO units in superconducting Ba(Pb1−xBix)O3 crystals with x1 = 0.19 an x2 = 0.28. We show here the feasibility of applying the scanning dispersive micro-X-ray absorption near edge structure (SdμXANES) technique, using focused synchrotron radiation, to probe the microscale spatial fluctuations of the microstrain in BPO units. This unconventional real-space SdμXANES microscopy at the Pb L3 edge has been collected in the dispersive mode. Our experimental method allows us to measure either the local Bi chemical concentration x and the local lattice microstrain of local BBO and BPO units. The 5 × 5 micron-size spots from the focused X-ray beam allowed us to obtain maps of 1600 points covering an area of 200 × 200 microns. The mapping shows a substantial difference between the spatial fluctuations of the microstrain ε and the chemical inhomogeneity x. Moreover, we show the different relations ε(x) in samples with lower (x1 = 0.19) and higher (x2 = 0.28) doping respect to the optimum doping (x = 0.25).

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