Characterization of YbBa2Cu3O7-y superconducting thin films prepared by chemical solution deposition on SrTiO3(001) and LaAlO3(001) substrates

c-axis oriented films of YbBa2Cu3O7-y have been prepared by postdeposition annealing of metal (Yb, Pa, Cu) naphthenate gels spin-coated on SrTiO3(001) and LaAlO3(001) substrates in the temperature range from 650 to 900 degree s C under oxygen partial pressures from about 10(5) to 10 Pa. High resoluti on electron microscopy studies showed that the thickness of the as-prepared c-axis YbBCO films was in the range from 80 to 100 nm after postdeposition annealing at 725 degrees C for the film on SrTiO3 and at 750 degrees C for the film on LaAlO3; above this thickness, a small amount of Yb2O3, CuO, an d random-oriented Yb123 phases were observed. The c-axis film obtained on t he SrTiO3(001) substrate is defective with stacking faults to form a defect microstructure rather than forming the well-ordered YbBa2Cu4O8 (Yb124) pha se. The film obtained on the LaAlO3(001) substrate, in contrast to that on SrTiO3, involves a small amount of a-axis Yb123 grains with dimensions of 5 to 30 nm. The T-c,T-zero value is 89 K for the film derived on SrTiO3 and 85.5 K for the film on LaAlO3.