Effect of Li doping and Li, La co-doping on the structure and physical properties of LaBa 2Cu 3O y

Abstract

Polycrystalline samples of LaBa 2Cu 3− x Li x O y (0⩽ x⩽0.7) and La 1+ x Ba 2− x Cu 3− x Li x O y (0⩽ x⩽0.7) were synthesized by the solid-state reaction method. The structure and physical properties were investigated by means of X-ray diffraction (XRD), resistivity, infrared (IR) transmission spectra and electronic spin resonance (ESR). With Li doping, an orthorhombic–tetragonal transition takes place as 0.3< x⩽0.5. While for La 1+ x Ba 2− x Cu 3− x Li x O y , the system remains orthorhombic structure within the entire doping range. Li doping and Li, La co-doping induce charge redistribution in the two systems and the single Li doping causes Cu 2+ spins to localize, especially for the x⩾0.5 samples. The changes of the IR and ESR spectra are analysed and discussed in detail.