Table 1 Materials, crystal structures, lattice parameters, and epitaxial relationships among the La-doped BaSnO₃ (BLSO) film, template layers, and (0001)-oriented Al₂O₃ substrate, and in-plane lattice mismatches

Film

La-doped BaSnO₃ (BLSO)

Cubic perovskite \((Pm\overline{3 }m)\)

a = 4.12 Å for BaSnO₃

–

Substrate

Al₂O₃

Hexagonal

\((R\overline{3 }c)\)

a = b = 4.76 Å,

c = 12.99 Å

γ = 120^o

–

Template layer

BaZrO₃/MgO

Cubic perovskite \((Pm\overline{3 }m)\)

Cubic halite \((Fm\overline{3 }m)\)

a = 4.19 Å

a = 4.20 Å

(111)BLSO || (111)BaZrO₃ || (111)MgO || (001)Al₂O₃

\([1\overline{1 }0]\) MgO || [100]Al₂O₃, lattice mismatch −19.9% (0.2% for 4:5 MgO:Al₂O₃)

\([1\overline{1 }0]\) BaZrO₃ || [\([1\overline{1 }0]\) MgO, 0.2%

\([1\overline{1 }0]\) BLSO || \([1\overline{1 }0]\) BaZrO₃, 1.7%

Template layer

MgO

Cubic halite \((Fm\overline{3 }m)\)

a = 4.20 Å

(111)BLSO || (111)MgO || (001)Al₂O₃

\([1\overline{1 }0]\) MgO || [100]Al₂O₃, lattice mismatch −19.9% (0.2% for 4:5 MgO:Al₂O₃)

\([1\overline{1 }0]\) BLSO || \([1\overline{1 }0]\) MgO, 1.9%

Template layer

Y-stabilized ZrO₂ (YSZ)

Cubic fluorite \((Fm\overline{3 }m)\)

a = 5.13 Å

(011)BLSO || (111)YSZ || (001)Al₂O₃

\([1\overline{1 }0]\) YSZ || [100]Al₂O₃, lattice mismatch −34.4%

(−1.6% for 2:3 YSZ:Al₂O₃)

[100]BLSO || \([1\overline{1 }0]\) YSZ, −11.9%

Template layer

Gd-doped CeO₂ (GDC)

Cubic fluorite \((Fm\overline{3 }m)\)

a = 5.41 Å

(011)BLSO || (111)GDC || (001)Al₂O₃

\([\overline{1 }\overline{1 }2]\) GDC || [100]Al₂O₃, 7.7%

\([0\overline{1 }1]\) BLSO || \([\overline{1 }\overline{1 }2]\) GDC, −19.5%