The ionic conductivity and thermo-Raman spectra of anhydrous sodium pyrophosphate Na4P2O7 were measured dynamically at 25 to 600C with a heating rate of 2C/min to understand the structural evolution and phase transformation involved. The DSC thermogram was also measured in the same thermal process for the phase transformation investigation. The spectral variations observed in the thermo-Raman investigation indicated the transformation of Na4P2O7 from low-temperature phase (ε) to high-temperature phase (α) proceeded through pre-transitional region from 75 to 410C before the major orientational disorder at 420C and minor structural modifications at 511, 540 and 560C. The activation energies and enthalpies of the proposed phase transformations were determined. The possible mechanism for temperature dependent conductivity in Na4P2O7 was compared with available data.

Ionic Conductivity and Raman Investigations on the Phase Transformations of Na4P2O7. R.Gangadharan, J.Kalaiselvi, D.Shanmukaraj, B.Palanivel, S.Mohan, R.Murugan: Journal of Alloys and Compounds, 2002, 340[1-2], 95-100