Temperature-dependent Raman spectra and thermal expansion of MgP₂O₆

The Raman spectra and thermal expansion of MgP₂O₆ metaphosphate were investigated at various temperatures up to 1073 K at ambient pressure. No temperature-induced phase transition was observed in this study. The effect of temperature on the Raman active vibrations and unit cell parameters was determined. All the observed Raman active bands of MgP₂O₆ showed linear temperature dependences in the range of -2.61 × 10^-2 ∼ -0.49 × 10^-2 cm^-1 K^-1. The thermal expansion coefficient of MgP₂O₆ was estimated to be 3.21(2) × 10^-5 K^-1. An axial anisotropic thermal expansion exists and the c-axis shows the smallest thermal expansion. The isobaric mode Grüneisen parameters of MgP₂O₆ were calculated. The obtained results were compared with other compounds in the MgO-P₂O₅ system.