Zinc phosphate chain length study under high hydrostatic pressure by Raman spectroscopy

The aim of this study is to combine a diamond anvil cell with in-situ Raman spectroscopy to simulate and analyze the effect of pure pressure on the length of phosphate chains in an antiwear film formed in a tribological contact. In-situ Raman spectra of Zn2P2O7 glass, α-Zn3(PO4)2, and γ−Zn2P2O7 crystals submitted to high hydrostatic pressure up to 20 GPa were recorded. Evolution of Raman spectra as a function of pressure was studied in the characteristic high frequency range of PO4 tetrahedra molecular resonance (650−1300 cm−1). When exposed to high pressure, the structure of the sample becomes less ordered. Phase transitions in α-Zn3(PO4)2 structure are observed during compression from ambient pressure to 3 GPa. The length of the phosphate chains is conserved up to 20 GPa when samples are subjected to hydrostatic pressure.