Structural phase transitions and their effects on oxygen diffusion in Y 2 (Zr 1-x Ti x ) 2 O 7 thin films
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Structural phase transitions and their effects on oxygen diffusion in Y2(Zr1‑xTix)2O7 thin films Li Lei1,2,3 · Jinzhan Li2 · Ruitao Zhang2 · Limin Li2 · Bo Deng1 · Gaoyang Zhao2,3 · Lihua Jin4 · Chengshan Li4 · Pingxiang Zhang4 Received: 29 August 2020 / Accepted: 10 November 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract 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(Zr1-xTix)2O7 (YZTO) thin films, as one kind of rare earth zirconates doped with T i4+ 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 Ti4+ ions into Y2Zr2O7 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 Ti4+ ions was increased. Remarkably, in YZTO thin films, the higher the doping ratios of T i4+ ions are, the stronger the ability to block oxygen diffusion will become. Keywords Y2(Zr1-xTix)2O7 thin films · Structural phase transition · Oxygen diffusion · Pyrochlore · Buffer layer
1 Introduction Due to their excellent performances, rare earth zirconate (A2Zr2O7) pyrochlore compounds have been extensively used in many kinds of application fields. For example, the front gas inlet temperature of aero-engine turbine blades coated with these thermal barrier coatings can reach up to 1873–1973 K, due to the extremely low thermal conductivities of rare earth zirconate A 2Zr2O7 with pyrochlore structure * Li Lei [email protected] * Gaoyang Zhao [email protected] 1
Advanced Material Analysis and Test Center, Xi’an University of Technology, Xi’an 710048, Shaanxi, People’s Republic of China
2
School of Material Science and Engineering, Xi’an University of Technology, Xi’an 710048, Shaanxi, People’s Republic of China
3
Key Laboratory of Electrical Materials and Infiltration Technology of Shaanxi Province, Xi’an 710048, Shaanxi, People’s Republic of China
4
Northwest Institute for Nonferrous Metal Research, Xi’an 710048, Shaanxi, People’s Republic of China
[1, 2]. However, the ionic conductivities of A 2Zr2O7 pyrochlore compounds are usually suppressed due to the highly ordered alignment of oxygen vacancies in A 2Zr2O7 lattice [3, 4]. This discovery can also be applied for Y2(ZryTi1-y)2O7 solid solutions in the literature [5]. It is concluded that the ionic conductivities of Y 2(Zr yTi 1-y) 2O 7 solid solutions decreased continuously as the ratios of Zr4+ ions became smaller, and Y 2(ZryTi1-y)2O7 transformed gradually from the fluorite into pyrochlore structure in this process. Both low thermal conductivities and supp
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