High-pressure investigations on urea hydrogen peroxide

The effect of high-pressure on the crystal structure of urea hydrogen peroxide has been investigated to 30 GPa. Through in-situ Raman scattering and ADXRD measurements, a first-order phase transition is concluded at 2.5GPa, and the new phase is indexed to a triclinic phase using Rietveld refinement method. Further increase in pressure up to 30 GPa does not show any structural phase transition. From the Raman analysis, the irreversible phase transition should be correlated with the twist structure of urea in the adduct of urea and hydrogen peroxide as a result of the cooperation and competition of inter-molecular hydrogen bonds.