密度是决定含能材料爆轰性能的重要参数。为评估现有CHON类含能材料密度的计算方法,对等电子密度面法、分子表面静电势法、基团加和法、晶体堆积法、定量构效关系法、经验公式法等进行分析和归类。结果表明,基于分子体积预测方法的精度...密度是决定含能材料爆轰性能的重要参数。为评估现有CHON类含能材料密度的计算方法,对等电子密度面法、分子表面静电势法、基团加和法、晶体堆积法、定量构效关系法、经验公式法等进行分析和归类。结果表明,基于分子体积预测方法的精度取决于分子间和分子内相互作用对密度影响描述的准确度。其中,准确描述氢键和van der Waals作用充满了挑战性。基于晶体体积计算密度的核心在于晶体结构的准确预测,结构搜索要面对巨大的状态空间和高度复杂的能量曲面的困难,预测效率是亟待解决的问题。体积加和法和经验公式法存在无法区分同分异构体和晶型的缺点,且对新发现的具有特殊结构的分子由于缺乏实验数据难以获得准确的经验参数,计算结果偏差较大。引入人工神经网络、遗传算法以及支持向量机等机器学习算法后,定量构效关系法在含能化合物性能与结构关系研究中取得很大成就,模型精度进一步提高将为基于材料基因组模式的含能材料设计研发奠定基础,这也是今后密度预测方法发展的主要方向。展开更多
As a fundamental thermodynamic variable, pressure can alter the bonding patterns and drive phase transitions leading to the creation of new high-pressure phases with exotic properties that are inaccessible at ambient ...As a fundamental thermodynamic variable, pressure can alter the bonding patterns and drive phase transitions leading to the creation of new high-pressure phases with exotic properties that are inaccessible at ambient pressure. Using the swarm intelligence structural prediction method, the phase transition of TiF_(3), from R-3c to the Pnma phase, was predicted at high pressure, accompanied by the destruction of TiF_6 octahedra and formation of TiF_8 square antiprismatic units. The Pnma phase of TiF_(3), formed using the laser-heated diamond-anvil-cell technique was confirmed via high-pressure x-ray diffraction experiments. Furthermore, the in situ electrical measurements indicate that the newly found Pnma phase has a semiconducting character, which is also consistent with the electronic band structure calculations. Finally, it was shown that this pressure-induced phase transition is a general phenomenon in ScF_(3), VF_(3), CrF_(3), and MnF_(3), offering valuable insights into the high-pressure phases of transition metal trifluorides.展开更多
The amount of sulfur in SO2 discharged in volcanic eruptions exceeds that available for degassing from the erupted magma.This geological conun drum,known as the"sulfur excess",has been the subject of conside...The amount of sulfur in SO2 discharged in volcanic eruptions exceeds that available for degassing from the erupted magma.This geological conun drum,known as the"sulfur excess",has been the subject of considerable interests but remains an open question.Here,in a systematic computational investigation of sulfur-oxygen compounds under pressure,a hitherto unknown S_(3)O_(4) compound containing a mixture of sulfur oxidation states+11 and+IV is predicted to be stable at pressures above 79 GPa.We speculate that S_(3)O_(4) may be produced via redox reactions involving subducted S-bearing minerals(e.g.,sulfates and sulfides)with iron and goethite under high-pressure conditions of the deep lower mantle,decomposing to SO2 and S at shallow depths.S_(3)O_(4) may thus be a key intermediate in promoting decomposition of sulfates to release SO2,offering an alter native source of excess sulfur released during explosive eruptions.These findings provide a possible resolution of the"excess sulfur degassing"paradox and a viable mechanism for the exchange of S between Earth's surface and the lower mantle in the deep sulfur cycle.展开更多
基金supported by the National Key Research and Development Program of China (2020YFB1506400)the National Natural Science Foundation of China (11974257)Jiangsu Distinguished Young Talent Funding (BK20200003)。
基金Jilin Provincial Science and Technology Development Joint Fund Project(YDZJ202201ZYTS581)Scientific and Technological Research Project of Jilin Province Education Department(Grant No.JJKH20240077KJ)。
文摘密度是决定含能材料爆轰性能的重要参数。为评估现有CHON类含能材料密度的计算方法,对等电子密度面法、分子表面静电势法、基团加和法、晶体堆积法、定量构效关系法、经验公式法等进行分析和归类。结果表明,基于分子体积预测方法的精度取决于分子间和分子内相互作用对密度影响描述的准确度。其中,准确描述氢键和van der Waals作用充满了挑战性。基于晶体体积计算密度的核心在于晶体结构的准确预测,结构搜索要面对巨大的状态空间和高度复杂的能量曲面的困难,预测效率是亟待解决的问题。体积加和法和经验公式法存在无法区分同分异构体和晶型的缺点,且对新发现的具有特殊结构的分子由于缺乏实验数据难以获得准确的经验参数,计算结果偏差较大。引入人工神经网络、遗传算法以及支持向量机等机器学习算法后,定量构效关系法在含能化合物性能与结构关系研究中取得很大成就,模型精度进一步提高将为基于材料基因组模式的含能材料设计研发奠定基础,这也是今后密度预测方法发展的主要方向。
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12034009, 91961204, and 11974134)。
文摘As a fundamental thermodynamic variable, pressure can alter the bonding patterns and drive phase transitions leading to the creation of new high-pressure phases with exotic properties that are inaccessible at ambient pressure. Using the swarm intelligence structural prediction method, the phase transition of TiF_(3), from R-3c to the Pnma phase, was predicted at high pressure, accompanied by the destruction of TiF_6 octahedra and formation of TiF_8 square antiprismatic units. The Pnma phase of TiF_(3), formed using the laser-heated diamond-anvil-cell technique was confirmed via high-pressure x-ray diffraction experiments. Furthermore, the in situ electrical measurements indicate that the newly found Pnma phase has a semiconducting character, which is also consistent with the electronic band structure calculations. Finally, it was shown that this pressure-induced phase transition is a general phenomenon in ScF_(3), VF_(3), CrF_(3), and MnF_(3), offering valuable insights into the high-pressure phases of transition metal trifluorides.
基金supported by the National Natural Science Foundation of China(12034009,91961204,11774127,12174142,11404128,11822404,52090024 and 11974134)the Program for Science and Technology Innovative Research Team of Jilin University。
文摘The amount of sulfur in SO2 discharged in volcanic eruptions exceeds that available for degassing from the erupted magma.This geological conun drum,known as the"sulfur excess",has been the subject of considerable interests but remains an open question.Here,in a systematic computational investigation of sulfur-oxygen compounds under pressure,a hitherto unknown S_(3)O_(4) compound containing a mixture of sulfur oxidation states+11 and+IV is predicted to be stable at pressures above 79 GPa.We speculate that S_(3)O_(4) may be produced via redox reactions involving subducted S-bearing minerals(e.g.,sulfates and sulfides)with iron and goethite under high-pressure conditions of the deep lower mantle,decomposing to SO2 and S at shallow depths.S_(3)O_(4) may thus be a key intermediate in promoting decomposition of sulfates to release SO2,offering an alter native source of excess sulfur released during explosive eruptions.These findings provide a possible resolution of the"excess sulfur degassing"paradox and a viable mechanism for the exchange of S between Earth's surface and the lower mantle in the deep sulfur cycle.
