“…We have also used the same value of the thickness (10 000 ) for making a comparison with α‐Al 2 O 3 and TiO 2 ceramic coatings. Then, in our calculations, the input densities of MgO, CaO, SrO, and BaO were 3.4, 3.34, 5.04, and 5.99 g/cm 3 , respectively, the mass of which was 40.3, 56.1, 103.6, and 153.3 amu, respectively, and the input thickness of the films was typically 5000 except the MgO having a thickness of 10 000 . As an input for E s of these protective layers, we have generally used the heats of sublimation, which were 6.73, 7.16, 6.29, and 4.8 eV, respectively, the same values as listed in Yoshimura et al However, experimental densities for different compounds were unavailable for α‐Al 2 O 3 /XO, TiO 2 /XO, and Al 2 TiO 5 /XO (X = Mg, Ca, Sr, and Ba).…”