Effect of Li doping and Li, La co-doping on the structure and physical properties of LaBa2Cu3Oy

Polycrystalline samples of LaBa2Cu3-xLixOy (0≤x≤0.7) and La1+xBa2-xCu3-xLixOy (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 La1+xBa2-xCu3-xLixOy, 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 Cu2+ spins to localize, especially for the x≥0.5 samples. The changes of the IR and ESR spectra are analysed and discussed in detail