Raman and luminescence studies on phase transition of EuNbO4 under high pressure

Raman and luminescence studies on the phase transition of europium orthoniobates(EuNbO4) under high pressure were performed. The pressure dependent Raman spectra revealed that an irreversible phase transition from monoclinic phase to M'-fergusonite phase of EuNbO4 occurred at 7.3 GPa, and the two phases coexisted over a pressure range from 7.3 to 13.7 GPa. An obvious discontinuity on luminescence intensity ratio between 5D0 →7F2 and 5D0→7F1 transitions was observed with increasing pressure, indicating also that a phase transition occurred at 7.3 GPa, which was in agreement with the high pressure Raman spectra data. Meanwhile, the Raman and luminescence spectra in the temperature range of 20–300 K showed the structure stability at low temperatures.     

RDX、HMX及CL-20晶体的高温高压相变研究进展

环三亚甲基三硝胺(RDX)、环四亚甲基四硝胺(HMX)和六硝基六氮杂异伍兹烷(CL-20)三种多晶型含能材料在高压/高温高压下具有丰富的相变行为及相变特征,本文总结了三种炸药在不同压力环境下的相变路径、部分相结构及p-T相图,为含能材料的爆轰行为和理论研究工作提供参考。根据目前的研究现状,发现在较复杂的相变研究上仍存在分歧,大部分高压相的结构还不明确,p-T相图不够完善,相变理论的研究也存在明显不足。指出探索含能材料的不同晶型间转化机理和获取更多相结构信息将是未来的重点研究方向。