Nd-Fe-B 永久磁石の電極です. パラマグネティック体力の理論的評価と実験的実証
Nicholas Leventis1, Xuerong Gao
1Department of Chemistry, University of Missouri-Rolla, 226 Schrenk Hall, Rolla, Missouri 65409, USA.
Journal of the American Chemical Society
|February 7, 2002
まとめ
ネオジミウム・鉄・ボロン (Nd-Fe-B) マグネット電極を用いたサイクルボルトメトリーは,従来の電極とは異なり,パラマグネット力による二磁性種に対する拡散制御です. これらの力,F (ΔB) とF (ΔC) は,自然コンベクションと磁気水力ダイナミックなを防ぐ.
科学分野:
- 電気化学 電気化学について
- 物理化学 物理化学
- マテリアルサイエンス 材料科学
背景:
- 従来の貴金属の電極を用いたサイクルボルトメトリーは,しばしば自然コンベクションを示し,拡散研究を複雑にします.
- ネオジム・鉄・ボロン (Nd-Fe-B) マグネット電極は,ユニークな磁場特性を有しています.
- コンベクティブ効果を理解することは,正確な電気化学分析に不可欠です.
研究 の 目的:
- Nd-Fe-B磁石電極を用いた二磁性還元活性種の電気化学的行動を調査する.
- 磁石電極の近くの質量輸送を制御するパラマグネット力の役割を明らかにする.
- 周期電圧測定における磁石電極と従来の電極の性能を比較する.
主な方法:
- サイクルボルトメトリーは, Nd-Fe-B ディスク磁石電極 (3.2 mm 直径) を用いて,スロー・スイープ・レート (<または = 0.01 V s(-1)) で実施した.
- 実験は,二磁性還元活性種 (TMPDなど) の濃縮溶液 (例えば80mM) で行われました.
- 分析には,磁場梯度に基づいて,磁気水力動力 (MHD) 力とパラ磁気体力 (F(ΔB,F(ΔC)) を評価することが含まれていた.
主要な成果:
- Nd-Fe-B電極と二磁性種を用いたサイクル電圧測定は,拡散制御であり,従来の電極で観測される拡散波は存在しない.
- MHDの振動がないのは,電流 (i) と磁場 (B) のベクトルが並列に並べられ,i x B の力を最小限に抑えるためです.
- マグネット電極から発生するパラマグネット体力,F (ΔB) とF (ΔC) は,自然コンベクションを効果的に抑制します. F ((ΔC) は平均してF ((ΔB) よりも強いことが判明しました.
- F ((ΔB) は,パラマグネティック・リドックス・アクティブ種が使用されたときに支配的になる.
- コンベクト的行動は,外部の反射磁石を導入することによって,ダイアマグネティックな種で誘導することができます.
結論:
- Nd-Fe-B磁石電極は,特定の条件下で,パラマグネット力による自然コンベクションを抑制することによって,拡散制御サイクル電圧測定を可能にします.
- 磁場グラデーションと濃度グラデーションの相互作用は,磁石電極の近くの質量輸送現象を決定する.
- 外部磁場操作は,電気化学システムにおけるコンベクティブ効果を制御するための方法を提供します.
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