Polymorphs with a face-centered cubic structure at room temperature were prepared by heat treatment in a humid or H-containing atmosphere. The lattice parameter was 0.7405nm. It was found that the ionic conductivities (table 176) were much higher for the cubic phases than for other polymorphs, and that proton conduction occurred in these materials.

B.Zhu, B.E.Mellander, J.Chen: Materials Research Bulletin, 1993, 28[2], 321-8

 

 

 

Table 176

Ionic Conductivities of Na3PO4 Polymorphs

 

Temperature (C)

Polymorph

 (S/cm)

E (eV)

400

c-Na3PO4

5.6 x 10-3

0.50

600

c-Na3PO4

2.9 x 10-2

0.50