Ionic conductivity of pure and doped Na3PO4

The ionic conductivity of pure and doped polycrystalline trisodium orthophosphate (Na3PO4) has been measured, using an ac technique, from 150 to 350°C. For the pure material, σ(300°C) ∼5 × 10−3 Ω−1 cm−1. Enhancement of conductivity is not achieved by doping with AlPO4, Na2SO4, or Na4SiO4 and activation energies in all cases are in the range 0.8–1.0 eV. At high levels of doping a low-melting-point glass, with good ionic conductivity, is produced in the Na3PO4AlPO4 system. Conductivity values are also reported for a sample of polycrystalline Ag3PO4.