Cr doping effects on structure and superconductivity of Ba2Ti2Fe2As4O

Chemical doping effects on structure and superconductivity were studied by introducing Cr at Fe sites in Ba2Ti2Fe2As4O, where Cr2+ can play dual role as impurities and hole dopants. Ba2Ti2(Fe1-xCrx)2As4O (0 ≤ x ≤ 8%) compounds are synthesized by a solid-state reaction and characterized with x-ray diffraction, electric resistivity and magnetization measurements. It is observed that the Cr dopants induce lattice expansion and local structure distortion, and significantly suppress the superconducting transition temperature Tc. In the meantime, the residual resistivity is found steadily increased with Cr doping. Comprehensive analyses show that Tc suppression is strongly correlated with the impurity-induced scattering to electrons, which can be fitted with the Abrikosov-Gor'kov-like scaling function.