PAPER: Thermal stability of magnetite particles made by an electrochemical method, 電気化学法で合成した磁気粒子の熱安定性

JOURNAL: Advanced Powder Technology, Available online 3 December 2012.

電気化学法による磁気ナノ粒子を合成し、その粒子の「熱安定性」を調べた研究。
(磁石の信頼性を評価するのに、熱安定性は重要な項目である)

For product’s durability (lifespan)
= To be durable and long‑lasting…

http://www.sciencedirect.com/science/article/pii/S0921883112001574

Thermal stability of silica-coated magnetite nanoparticles prepared by an electrochemical method
Fauziatul Fajaroh, Heru Setyawan, Adrian Nur, I. Wuled Lenggoro
– Department of Chemistry, Faculty of Mathematics and Natural Science, Malang State University, Malang, Indonesia
– Department of Chemical Engineering, Faculty of Industrial Technology, Sepuluh Nopember Institute of Technology (ITS), Surabaya, Indonesia.
– Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Tokyo, Japan

fauziah-figure2012

Magnetite nanoparticles have been prepared by electrooxidation of iron in water. Surface modifications have been conducted by coating the nanoparticles with silica by a one-step synthesis in dilute sodium silicate solution. The mean size of particles was approximately 10–30 nm for the uncoated particles and 9–12 nm for the coated particles. The results obtained from thermal gravimetric/differential thermal analysis (TG/DTA) revealed that the silica layer formed by the electrochemical method was stable and could serve as a protective layer. Annealing the nanoparticles at 550 °C converts magnetite into maghemite for the silica-coated particles, and it further converts the uncoated particles into hematite. The conversions cause the saturation magnetization to decrease for all samples.

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