E-Beam Deposition of Scandia-Stabilized Zirconia (ScSZ) Thin Films Co-Doped with Al

Abstract

Scandia alumina stabilized zirconia (ScAlSZ) thin films were deposited using e-beam evaporation, and the effects of deposition parameters on the structure and chemical composition were investigated. The analysis of thin films was carried out using Energy-dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-Ray Diffraction Analysis (XRD) and Raman spectroscopy methods. It was found that the chemical composition of ScAlSZ thin films was different from the chemical composition of the initial powder. Moreover, the Al concentration in thin films depends on the deposition rate, resulting in a lower concentration using a higher deposition rate. XPS analysis revealed that ZrOx, oxygen vacancies, high concentrations of Al2O3 and metallic Al exist in thin films and influence their structural properties. The crystallinity is higher when the concentration of Al is lower (higher deposition rate) and at higher substrate temperatures. Further, the amount of cubic phase is higher and the amount of tetragonal phase lower when using a higher deposition rate.

Structural and Electrochemical Properties of Scandia Alumina Stabilized Zirconia Thin Films

“…Therefore, a smaller amount of Al evaporated using a higher deposition rate for the same thickness of the thin film. The influence of deposition rate on the chemical composition was similar to the published results [17]. Moreover, the metallic Al or its compound phases in ScAlSZ thin films could form due to high Al concentrations exceeding the solubility limit (~7 at.%) [54].…”

“…The shape of Raman spectra (Figure 7) of annealed ScAlSZ thin films containing 15.9 and 22.2 at.% of Al were different compared to as-deposited. Raman peaks about 150 cm −1 (A 1g ), 265 cm −1 (E g ), 460 cm −1 (A 1g ), and 645 cm −1 (A 1g ) belong to the tetragonal (t-ZrO 2 ) phase [17,37,41,42,53]. Peaks about 202 cm −1 and 346 cm −1 belong to the monoclinic (m-ZrO 2 ) phase [26,36,37].…”

“…A weak peak around 535 cm −1 (B g ) and a strong, sharp peak centered around 560 cm −1 (A g ) belong to the rhombohedral (β-ZrO 2 ) phase [16,36,42]. One Raman active vibration F 2g of the cubic (c-ZrO 2 ) phase should be expressed as a broad line peak between 600 and 630 cm −1 [16,17,43]. The peaks indicating the cubic (c) phase of ZrO 2 are not prominently expressed, and the Raman peaks at 621 cm −1 (F 2g ) and 645 cm −1 (A 1g ) are merged into one broad peak, possibly due to impurities at the grain boundaries [53].…”

“…Yet, co-doping with alumina gives contradictive results. Other authors found that 5.5 mol.% and higher alumina concentrations do not fully stabilize the cubic phase [15][16][17]. The additional phases exist, reducing the ionic conductivity.…”

Effects of Oxygen Partial Pressure and Substrate Temperature on the Structure and Morphology of Sc and Y Co-Doped ZrO2 Solid Electrolyte Thin Films Prepared via Pulsed Laser Deposition

“…PES peaks position for Zr 3d is at 181 eV to 183 eV which corresponds to the Zr 4+ valence state. On the other hand, for Y 3d, the peak position is at around 158 eV for Y 3+ valence state [40,41] and the peaks for Sc 2p are at around 402 eV to 403 eV for the Sc 3+ valence states [38,42]. For the O 1s core levels, the peaks are expected at binding energies around 530 eV to 532 eV for lattice oxygen and hydroxyl [39], respectively, and O KLL is expected at 92 eV.…”