11:00 〜 11:30
[SEM15-07] 超高速遊星ボールミルを用いた衝突格子圧縮プロセスによる高圧無機物質・材料創製
★招待講演
キーワード：カーボンナノ材料、炭素系宇宙塵、格子圧縮イルメナイト－ヘマタイト固溶体、惑星磁気異常
We report a simple shock event approach inspired by the Allende meteorite to produce sophisticated carbon nanomaterials. It is demonstrated that unique carbon nanostructures, including carbon nanotubes, carbon onions, and new carbon nanorings are synthesized by high-speed ball-milling of steel balls. The carbon nanorings have diameter of several ten nanometers. It is considered that the carbon nanomaterials are formed from around the surface of steel balls under local high temperatures induced by the collision energy in ball-milling process.
Also, we report that defective graphitic nanostructures prepared by high-energy collisions exhibit an ultraviolet (UV) absorption feature at 220 nm that we suggest accounts for the UV interstellar extinction at 217.5 nm. The morphology of some graphitic nanostructures is similar to that of nanocarbons discovered in the Allende meteorite. The similarity between the absorption feature of the defective graphitic nanostructures and UV interstellar extinction indicates strong correlation between the defective graphitic nanostructures and interstellar dust.
Then, we report a compressed ilmenite–hematite solid solution as a new potential source of Earth’s magnetic anomalies. The 0.5FeTiO3·0.5Fe2O3 solid solution compressed by collision synthesis with super-high-energy ball milling showed a decrease in molar volume of approximately 1.8%. Consequently, the sample showed a saturation magnetization of 1.5 Am2/kg at 300 K, a Curie temperature of 990 K and a magnetic exchange bias below 100 K, e.g., 1.7 × 105 A/m at 60 K. Ilmenite–hematite solid solutions are common mineral systems in most mafic igneous and metamorphic rocks, and the compressive force in the rocks is generated by the high pressure in the upper mantle or by shock events with high pressure such as the collision of these rocks with meteorites. Therefore, we consider that the compressed ilmenite–hematite solid solution is an additional candidate source of other planetary magnetic anomalies including those in the Moon and Earth.
References
[1] S. Ohara, Z. Tan, J. Noma, T. Hanaichi, K. Sato, and H. Abe, “Collision Synthesis of Unique Carbon Nanomaterials Inspired by the Allende Meteorite”, Solid State Comm., 150, p.198-200, (2010).
[2] Z. Tan, H. Chihara, C. Koike, H. Abe, K. Kaneko, K. Sato, and S. Ohara, “Interstellar Analogues from Defective Carbon Nanostructures Account for Interstellar Extinction”, Astronomical Journal, 140, p.1456-1461, (2010).
[3] T. Hashishin, Z. Tan, K. Yamamoto, Q. Nan, J. Kim, C. Numako, T. Naka, J.-C. Valmalette, and S. Ohara, “Quenching Ilmenite with a High-Temperature and High-Pressure Phase using Super-High-Energy Ball Milling”, Scientific Reports, 4, p.4700-1-6, (2014).
[4] S. Ohara, T. Naka, K. Sunakawa, S. Kubuki, M. Senna, and T. Hashishin, “Emergence of Ferromagnetism due to Charge Transfer in Compressed Ilmenite Powder using Super-High-Energy Ball Milling”, Scientific Reports, 10, p.5293-1-7, (2020).
[5] S. Ohara, T. Naka, and T. Hashishin, “Ferromagnetism and exchange bias in compressed ilmenite–hematite solid solution as a source of planetary magnetic anomalies”, Science Advances, 8, eabj2487, (2022).
Also, we report that defective graphitic nanostructures prepared by high-energy collisions exhibit an ultraviolet (UV) absorption feature at 220 nm that we suggest accounts for the UV interstellar extinction at 217.5 nm. The morphology of some graphitic nanostructures is similar to that of nanocarbons discovered in the Allende meteorite. The similarity between the absorption feature of the defective graphitic nanostructures and UV interstellar extinction indicates strong correlation between the defective graphitic nanostructures and interstellar dust.
Then, we report a compressed ilmenite–hematite solid solution as a new potential source of Earth’s magnetic anomalies. The 0.5FeTiO3·0.5Fe2O3 solid solution compressed by collision synthesis with super-high-energy ball milling showed a decrease in molar volume of approximately 1.8%. Consequently, the sample showed a saturation magnetization of 1.5 Am2/kg at 300 K, a Curie temperature of 990 K and a magnetic exchange bias below 100 K, e.g., 1.7 × 105 A/m at 60 K. Ilmenite–hematite solid solutions are common mineral systems in most mafic igneous and metamorphic rocks, and the compressive force in the rocks is generated by the high pressure in the upper mantle or by shock events with high pressure such as the collision of these rocks with meteorites. Therefore, we consider that the compressed ilmenite–hematite solid solution is an additional candidate source of other planetary magnetic anomalies including those in the Moon and Earth.
References
[1] S. Ohara, Z. Tan, J. Noma, T. Hanaichi, K. Sato, and H. Abe, “Collision Synthesis of Unique Carbon Nanomaterials Inspired by the Allende Meteorite”, Solid State Comm., 150, p.198-200, (2010).
[2] Z. Tan, H. Chihara, C. Koike, H. Abe, K. Kaneko, K. Sato, and S. Ohara, “Interstellar Analogues from Defective Carbon Nanostructures Account for Interstellar Extinction”, Astronomical Journal, 140, p.1456-1461, (2010).
[3] T. Hashishin, Z. Tan, K. Yamamoto, Q. Nan, J. Kim, C. Numako, T. Naka, J.-C. Valmalette, and S. Ohara, “Quenching Ilmenite with a High-Temperature and High-Pressure Phase using Super-High-Energy Ball Milling”, Scientific Reports, 4, p.4700-1-6, (2014).
[4] S. Ohara, T. Naka, K. Sunakawa, S. Kubuki, M. Senna, and T. Hashishin, “Emergence of Ferromagnetism due to Charge Transfer in Compressed Ilmenite Powder using Super-High-Energy Ball Milling”, Scientific Reports, 10, p.5293-1-7, (2020).
[5] S. Ohara, T. Naka, and T. Hashishin, “Ferromagnetism and exchange bias in compressed ilmenite–hematite solid solution as a source of planetary magnetic anomalies”, Science Advances, 8, eabj2487, (2022).