Tensile Microstrain Fluctuations in the BaPbO Units in Superconducting BaPb1−xBixO3 by Scanning Dispersive Micro-XANES

BaPb1−xBixO3 (BPBO) bismuthate, showing high TC superconductivity for 0.05 < x 0.35, is an archetypal system studying the complex inhomogeneity of perovskite lattice favoring emergence quantum coherence, called superstripes phase. Local fluctuations, detected by EXAFS; nanoscale stripes, electron microscopy; and two competing crystalline structures, diffraction, are known to characterize superconducting At [BaBiO3] centered units (BBO) coexist with BaPbO3 (BPO) in BPBO perovskite; therefore, we expect a tensile microstrain BPO due misfit strain between different lattices. Here, report measurement spatial micro-fluctuations local ε BaPO Ba(Pb1−xBix)O3 crystals x1 = 0.19 x2 0.28. We show here feasibility applying scanning dispersive micro-X-ray absorption near edge structure (SdμXANES) technique, using focused synchrotron radiation, probe microscale fluctuations units. This unconventional real-space SdμXANES microscopy at Pb L3 has been collected mode. Our experimental method allows us measure either Bi chemical concentration BBO The 5 × micron-size spots from X-ray beam allowed obtain maps 1600 points covering area 200 microns. mapping shows substantial difference x. Moreover, relations ε(x) samples lower (x1 0.19) higher (x2 0.28) doping respect optimum (x 0.25).