Effect of shock compression on optical and structural properties of Eu2O3 and Y2O3:Eu3+ powders

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Shock-recovery experiments on Eu2O3 and Y2O3:Eu3+ powders using a metal plate projectile accelerated by a single-stage powder-propellant gun were performed to investigate phase stability and response at high pressures and temperatures. The recovered samples were characterized using powder X-ray diffraction analysis and photoluminescence spectroscopy. The onset of the structural phase transition from the cubic (C-type) to monoclinic (B-type) phase was observed for both Eu2O3 and Y2O3:Eu3+ powders at shock pressures of 8 and 13 GPa, respectively. For Eu2O3, the amount of B-type phase increases with increasing shock pressure up to 23 GPa, whereas for Y2O3:Eu3+, a maximum was reached at 25 GPa followed by a decrease with increasing shock pressure; only the C-type phase was detected in the sample shocked at 51 GPa. The change in the amount of B-type phase indicates stability for the monoclinic phase against shock-induced heat and mechanical deformation. The large range in shock pressure for which the C-type and B-type phases coexist in Eu2O3 and Y2O3:Eu3+ indicates that the pressure-induced phase transition is too sluggish to be completed within the shock duration. The D50→7F2/5D0→7F1 intensity ratios for the shock-recovered Eu2O3 and Y2O3:Eu3+ samples were independent of the shock pressure and the amount of C-type phase in the samples. No relationship was observed between the crystal-field parameter B20 and the amount of C-type phase in both shock-recovered samples. However, with increasing B20 2, the D50→7F2/5D0→7F1 intensity ratio decreased, whereas the D50→7F0/5D0→7F1 intensity ratio increased. These results suggest that shock-induced deformation leads to enhanced J-mixing in both the Eu2 O3 and the Y2O3:Eu3+ samples.