在高达50GPa的MnN中寻找结构和相位关系:DFT研究
Nursultan E Sagatov1, Aitolkyn S Omarkhan2, Assyl-Dastan B Bazarbek2
1Sobolev Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Science, Novosibirsk 630090, Russian Federation. n.e.sagatov@gmail.com.
Physical chemistry chemical physics : PCCP
|November 15, 2024
概括
这项研究揭示了高达50GPa的化 (MnN) 的稳定结构和压力-温度场. MnN不是硬材料,其高压阶段被确定为扭曲的NiAs型结构.
科学领域:
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
- 计算材料科学科学 计算材料科学
背景情况:
- 了解过渡金属化物如化 (MnN) 的压力-温度 (P-T) 阶段图对于预测它们在极端条件下的行为至关重要.
- 以前的实验和理论研究已经为MnN结构提供了洞察力,但缺乏全面的P-T稳定性图.
研究的目的:
- 确定MnN的热力学稳定结构及其在广泛压力范围内 (0-50 GPa) 的稳定场.
- 确定最近合成的MnN高压相的晶体结构.
- 评估各种MnN多态的机械性能,特别是硬度.
主要方法:
- 利用密度函数理论 (DFT) 结合进化算法来预测稳定的MnN结构.
- 在0-50 GPa压力范围内计算的相位边界和稳定场.
- 估计的机械性能,包括维克斯硬度 (Hv),所有已识别的MnN多态.
主要成果:
- 确定了MnN-F4̄3m (混合型) 作为环境压力阶段.
- 确定实验已知的MnN-I4 / mmM (扭曲的NaCl类型) 是一个高温相.
- 揭示了相位过渡:MnN-F4̄3m到MnN-P63/mmc (NiAs类型) 在5.0 GPa和<500 K,MnN-P63/mmc到MnN-I4/mmm随着温度的增加.
- 确立了MnN-Pnma (扭曲NiAs型) 作为41.2GPa以上的稳定相,证实了其作为最近合成的高压相的身份.
- 计算了所有多态的维克斯硬度,表明它们都低于硬材料的20 GPa值.
结论:
- 该研究为MnN提供了全面的P-T相图,澄清了各种多态的稳定性.
- 在~55 GPa以上合成的高压阶段的MnN具有扭曲的NiAs型结构 (MnN-Pnma).
- 所有研究的MnN多态都不符合被归类为硬材料的标准.
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