The mechanism and kinetics of water incorporation into the double perovskite was investigated at 300 to 500C, for aH2O = 10−3 to 2.2 x 10−2. The formation of hydration

products, Sr6Ta2O11xH2O (0.2 < x < 0.50) was limited by the diffusion of H2O. There was a small increase in DH2O with increasing x. The temperature dependences of the chemical diffusion coefficients of water for Sr6Ta2O110.35H2O (figure 35) could be described by an activation energy of 0.49eV.

Chemical Diffusion of Water in the Double Perovskites Ba4Ca2Nb2O11 and Sr6Ta2O11. I.Animitsa, A.Neiman, N.Kochetova, D.Korona, A.Sharafutdinov: Solid State Ionics, 2006, 177[26-32], 2363-8

Table 195

Self-Diffusion of 44Ti in Strontium Niobium Titanates

Figure 35

Diffusion of H2O in Sr6Ta2O11