Effects of growth conditions on one-dimensional nanorod growth in REBa2Cu3O7-δ films

The effects of growth conditions on one-dimensional nanorods in ErBa2Cu3O7-θ films are discussed in terms of their microstructures and superconducting properties. The Ba(Er0.5Nb0.5)O3 nanorods were observed clearly in transmission electron microscopy images of the films. Nanorod morphologies were controlled by managing the growth temperature (TS) and BNO-doping concentration. The nanorods were thinner and denser at a lower TS under a constant BNO-doping concentration. In case of TS=710degC, the diameter and number density of nanorods with 1.5 wt% BNO-doping were 4-6 nm and 2.6x1011/cm2, respectively. As the BNO-doping concentration increased, nanorods were almost aligned in the c-axis direction and grew in uniform size from the substrate to the film surface. The diameter and number density of the nanorods with 5 wt% BNO-doping were ∼10 nm and 2.2x1011/cm2, respectively. These nanorods could effectively act as c-axis correlated pinning centers. Consequently, the pinning effects were controlled by their diameter, number density and growth direction of the nanorods by varying the growth conditions. (author)