  Epitaxial growth of Ba0.6Sr0.4Ti1-xZrxO3 (0/leqx\leq0.3) composition spread
thin film library on SrRuO3/SrTiO3 layer by combinatorial pulsed laser
deposition (PLD) is reported. X-ray diffraction and energy dispersive x-ray
spectroscopy studies showed an accurate control of the film phase and
composition by combinatorial PLD. A complex evolution of the microstructure and
morphology with composition of the library is described, resulting from the
interplay between epitaxial stress, increased chemical pressure and reduced
elastic energy upon Zr doping. Statistical and temperature-related capacitive
measurements across the library showed unexpected variations of the dielectric
properties. Doping windows with enhanced permittivity and tunability are
identified, and correlated to microstructural properties.
