The self-diffusion of 22Na, 99Mo, and 147Pm was studied by using a radiometric method; where the Pm played the role of a La isotope. The results for Mo could be described by:

1170-1270K:     D (cm2/s) = 0.0014 exp[-199.8(kJ/mol)/RT]

while those for Na were described by:

1120-1320K:     D (cm2/s) = 0.0016 exp[-177.3(kJ/mol)/RT]

The dependence of the latter upon partial O activity at 1188K was given by:

D (cm2/s) = 3 x 10-11 aO21/50

when aO2 was between 0.0001 and 1. The diffusivity of Pm at 1320K was 8 x 10-12cm2/s. From these data, it was calculated that the total conductivity at 1kHz was such that:

C (S/cm) = 0.025 exp[-131.0(kJ/mol)/RT]

and that the fraction which was due to ionic conduction varied from 0.5 at 1030K to 0.17 at 1270K.

A.J.Neiman, A.S.Kalyakin, A.F.Guseva: Izvestiya Akademii Nauk SSSR Neorganicheskie Materialy, 1990, 26[8], 1728-33. [Inorganic Materials, 1990, 26[8], 1474-81

Table 144

Ionic Conduction in (NaFeO2)1-x(SiO2)x Solid Solutions