Structural phase transitions and their effects on oxygen diffusion in Y${}_2$(Zr${}_{1-x}$Ti${}_x$)${}_2$O${}_7$ thin films

Rare earth zirconate pyrochlore compounds with their unique crystal structure have been extensively used as thermal barrier coatings, ionic conductors and buffer layer for high-temperature coated conductors. In this work, Y${}_2$(Zr${}_{1-x}$Ti${}_x$)${}_2$O${}_7$ (YZTO) thin films, as one kind of rare earth zirconates doped with Ti${}^{4+}$ ions, were employed to investigate the structural phase transition and its effect on oxygen diffusion in YZTO thin films. YZTO thin films were prepared on single-crystal silicon substrates by sol–gel method with adding a certain amount of Ti${}^{4+}$ ions into Y${}_2$Zr${}_2$O${}_7$ precursor solution. It was found that the crystal structure of YZTO thin films started gradually to transform from defective fluorite structure with disordered oxygen vacancies to pyrochlore structure with highly ordered oxygen vacancies as the doping ratio of Ti${}^{4+}$ ions was increased. Remarkably, in YZTO thin films, the higher the doping ratios of Ti${}^{4+}$ ions are, the stronger the ability to block oxygen diffusion will become.