Structural and electronic properties of Pr1-xCaxBa2Cu3O7-y (0 <= x <= 0.5)thin films deposited by PLD on (100) SrTiO3 and (100) YSZ substrates at different temperatures

Epitaxial Pr1-xCaxBa2Cu3O7-y (0 less than or equal to x less than or equal to 0.5) thin films were deposited on SrTiO3 and YSZ substrates by PLD at di fferent temperatures. Short and long range order in the crystalline structu re as well as the direction of crystal growth on the substrate, being relev ant issues in the transport properties of the material, were studied by sca nning (SEM) and transmission (TEM) electron microscopy as well as X-ray dif fraction (XRD) fur their microstructure characterization. XRD and TEM studi es revealed epitaxial growth on YSZ substrates (for 0 less than or equal to x less than or equal to 0.3) along a and c axis at temperatures of 550 and 600 degrees C, respectively. For the films on SrTiO3 a preferential growth along c-axis was observed with a small fraction oriented along the a-axis at temperatures as high as 650 degrees C. Thr four probe method was used to obtain the rho vs, T curves, where a typical hopping conduction mechanism between localized states was observed. (C) 2000 Elsevier Science Ltd. All r ights reserved.