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

Abstract

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.

Photoluminescence properties of shock-modified Tb2O3

“…In contrast with Tb 2 O 3 , PL spectra of Er 2 O 3 and Eu 2 O 3 having a monoclinic structure (B-type) are dissimilar to those of Er 2 O 3 and Eu 2 O 3 having a cubic structure (C-type). 5,37,38) To characterize effects of shock compression on photoluminescence spectra of Tb 2 O 3 , the PL intensity and the intensity ratios of the PL and PLE peaks for the unshocked and the shocked sample were analyzed. Figure 5 shows that the PL intensity, the intensity ratio of subpeaks for the 5 D 4 → 7 F 5 transition, I 543 /I 550 , the intensity ratio of the 5 D 4 → 7 F 5 and 5 D 4 → 7 F 6 transitions, I 5D4-7F5 /I 5D4-7F6 , along with the intensity ratio of the PLE peaks at 353 and 378 nm as a function of the yield of B-type Tb 2 O 3 .…”

“…Shock recovery experiments were conducted using a 30 mm barrel diameter, single-stage powder-propellant gun. 4,5,18,19) A projectile, which was accelerated by the gun, was impacted onto a target assembly in an experimental chamber. The target assembly was composed of a copper capsule embedded in a 70 mm diameter steel block backed with a momentum trap.…”

“…Generally, the local environment around activators in a host material has an effect on the intensity of the transition between different energy levels and these changes can lead to changes in PL spectra. 4,5) Rare-earth (RE) sesquioxides (RE 2 O 3 , RE = Y, Sc, or lanthanide) are currently being extensively studied owing to their potential application in a wide range of technological devices. Among them, the most well-known application of Tb 2 O 3 is as a phosphor for green light emission.…”

“…The structural behavior subjected to RE 2 O 3 for shock compression has been investigated. 4,5,17) However, no shock compression study of Tb 2 O 3 has been reported. Given the importance of Tb 2 O 3 for luminescent and optoelectric materials, shock-induced modification of optical properties of Tb 2 O 3 are of interest.…”

Effect of dynamic high-pressure loading on decomposition reaction and negative thermal expansion of silver oxide

“…A series of shock compression experiments was performed by impacting encapsulated Ag 2 O samples with a 30 mm diameter projectile using a powder gun. [24][25][26] The projectile was composed of a metal plate attached to a sabot made from a polycarbonate cylinder. The projectile velocity was measured using a magnetic flyer technique with a magnet embedded in the projectile and a pair of coils mounted in the gun barrel.…”