Effects of Excess Barium on the Microstructure and Proton Conductivity of Ba1+xZr0.8Y0.2O3-δ (0 ≤ x ≤ 0.3) Thin Films

Yttrium-doped barium zirconate (BZY) thin films are widely used in the field of hydrogen energy because of their excellent proton conductivity and chemical stability. However, the existence of barium defects in BZY thin films fabricated by pulsed laser deposition (PLD) significantly hinders their intrinsic conductivity. In this regard, regulating the A-site nonstoichiometry for Ba-containing proton conductor oxides could control the proton transport properties. Herein, we used a target compensation strategy to compensate for the Ba loss in BZY thin films. We synthesized a series of nonstoichiometry graded Ba1+xZr0.8Y0.2O3-δ (Ba1+xZrY, 0.0 ≤ x ≤ 0.3) targets for growing Ba1+xZrY (0.0 ≤ x ≤ 0.3) thin films on MgO (100) substrates by PLD. The results show that the conductivity of the Ba1.3ZrY thin films is 1 order of magnitude larger than that of the Ba1·0ZrY thin films, exhibiting also lower activation energy. The structural characterization shows that the target compensation strategy can effectively fill the Ba vacancy and promote the proton transport of the Ba1+xZrY films, mainly attributed to the prolonged Zr-O bond length and increased Y dopant effective concentration.