Study of anomalous microstructure changes in Mn-doped Bi2201 system

We report herein anomalous microstructure changes in Bi2201 system, which is induced by 3d transition metal Mn substitution at Cu-site. The Mn-doped Bi2201 polycrystalline samples, Bi1.6Pb0.4Sr1.6La0.4Cu1−xMnxOz (0 ⩽ x ⩽ 0.4) and Bi1.6Pb0.4Sr1.6+2xLa0.4−2xCu1−2xMnxOz (0 ⩽ x ⩽ 0.2), were investigated systematically by means of X-ray diffraction (XRD), Raman scattering and infrared (IR) spectra, respectively. Our experimental results revealed that the microstructure of Bi2201 phase was affected strongly by Mn doping in CuO2 plane. With the increase of Mn doping content, anomalous changes of the lattice parameters have been found in Bi1.6Pb0.4Sr1.6La0.4Cu1−xMnxOz (0 ⩽ x ⩽ 0.4) system. The anomalous microstructure changes were largely attributed to the strong Jahn-Teller distortion of MnO6 octahedron induced by Mn3+ ions and charge-transfer effects induced by the aliovalent substitution of Mn3+/Mn4+ ions for Cu2+.