Challenge to elemental magnetic separation method based on equilibrium phase diagram in strong magnetic field

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K18833
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 26:Materials engineering and related fields
• Research Institution: Kagoshima University
• Principal Investigator: KOYAMA Keiichi 鹿児島大学, 理工学域理学系, 教授 (70302205)
• Co-Investigator(Kenkyū-buntansha): 三井 好古 鹿児島大学, 理工学域理学系, 准教授 (90649782)
• Project Period (FY): 2021-07-09 – 2024-03-31
• Keywords: 強磁場 / 合成 / 分離

Outline of Final Research Achievements

Equilibrium phase diagrams including magnetic phases can be controlled by a strong magnetic field. A strong magnetic field preferentially synthesizes ferromagnetic materials from raw materials in the direction that maximizes the magnetic energy gain, thermally stabilizing them and suppressing thermal decomposition. A new magnetic separation technique was attempted by applying a strong magnetic field to a sample containing multiple elements, selectively synthesizing ferromagnetic compounds and eliminating other elements. In particular, in Mn-Bi-Sn-based samples, no compound synthesis occurs at low temperatures, but when a strong magnetic field is applied, the ferromagnetic MnSb phase is preferentially synthesized, with Mn and Bi remaining. At high temperatures, Mn2Sb is synthesized and Bi can be separated. This research has revealed new magnetic field effects, such as reaction rate control, reactant selection, and element concentration by applying a strong magnetic field.

Free Research Field

磁気物理学

Academic Significance and Societal Importance of the Research Achievements

磁性化合物の合成において、従来は原料組成比と熱処理温度を制御し目標物質を合成してきた。本研究によって、化合物に強磁性が含まれる場合、温度と磁場を制御すれば、組成比の異なる化合物が選択的に合成でき、合成に関与しない元素が分離できることを初めて示すことができた。この成果は磁場が温度や組成比と同様に、物質合成の重要な熱力学的パラメータの一つであること意味し、磁場中物質合成の新しい手法として学術的及び社会的意義は大きい。