High Pressure Phase Transition of HMX Crystal under Non-Hydrostatic Pressure
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摘要: HMX是一种性能优良的高能炸药,在武器工业中广泛使用。目前,HMX在高压下特别是非静水压下的相变规律仍存在争议。为此,采用不同的传压介质,开展了非静水压下HMX晶体的高压拉曼实验研究。结果表明,HMX晶体分别在4.9、13.9和17.5 GPa发生了结构相变。在13.9 GPa下,HMX开始发生相Ⅱ→相Ⅲ的相变,并在一定的压力范围内两相共存;当压力为17.5 GPa时,出现另一个新相(相Ⅳ),在17.5~23.6 GPa的压力范围内出现相Ⅱ、相Ⅲ和相Ⅳ三相共存现象。HMX晶体在非静水压下的相变路径与准静水压下的相变路径完全不同,非静水压环境下的压力梯度是造成该差异的原因。Abstract: HMX is a high-energy explosive with excellent performance and is widely used in weapons. The phase transition law of HMX, especially under non-hydrostatic pressure, is controversial. In this work, a high-pressure Raman experimental study of HMX crystals under non-hydrostatic pressure was carried out using different pressure-transmitting media. The HMX crystal undergoes three phase transitions at pressures of 4.9, 13.9 and 17.5 GPa, respectively. Under the pressure of 13.9 GPa, HMX began to undergo phase transition from structure Ⅱ to structure Ⅲ, and the two phases existed simultaneously within a certain pressure range; another new phase (structure Ⅳ) began to appear from 17.5 GPa. The three-phase coexistence of structure Ⅱ, structure Ⅲ and structure Ⅳ appeared in the pressure range of 17.5−23.6 GPa. Importantly, the phase transition process of HMX crystals under non-hydrostatic pressure is completely different from the phase transition path under quasi-hydrostatic pressure, and the pressure gradient under non-hydrostatic pressure environment is the reason for the difference.
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Key words:
- HMX crystal /
- Raman spectrum /
- phase transition /
- non-hydrostatic pressure
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表 1 拉曼波数及其归属模式
Table 1. Frequencies of Raman modes of HMX
Wavenumber/cm−1 Assignment Wavenumber/cm−1 Assignment Wavenumber/cm−1 Assignment 94 τ(ring) + γ(N–N) 717 τ(ring) + γ(NO2) 1364 ω(CH2) 127 τ(NO2) 758 γ(NO2) 1416 δ(CH2) 134 831 ν(ring) 1433 152 880 1450 176 949 ν(ring) + ρ(CH2) 1456 182 τ(ring) + γ(N–N) 962 1505 νas(NO2) 231 ν(ring) + τ(ring) 1077 1519 281 1090 1530 314 1165 1555 362 1187 1566 415 1238 νs(NO2) + νs(N–N) 2982 νs(CH2) 436 1263 2992 594 τ(ring) + γ(NO2) 1306 γ(CH2) 3027 νas(CH2) 635 1315 νs(NO2) 3036 658 1346 γ(CH2) Note: as–anti-symmetric; s–symmetric; ν–stretching; δ–deformation motion; τ–torsional motion; γ–deformations involving
one ring and one non-ring bond; ω(XY2)–wag of Y2 atoms out of XY2 plane; ρ(XY2)–rocking in XY2 plane. -
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