Effect of Heat-Treatment Temperatures on Magnetite Oxidation in
20SiO2.50FeO.30CaO Glass Ceramic Prepared by the Sol-Gel Method

rastgoo oskoui, parisa; rezvani, mohammad; kianvash, Abbas

doi:10.22068/ijmse.3238

Volume 20, Issue 2 (June 2023) IJMSE 2023, 20(2): 1-11 | Back to browse issues page

‎ 10.22068/ijmse.3238

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rastgoo oskoui P, rezvani M, kianvash A. Effect of Heat-Treatment Temperatures on Magnetite Oxidation in 20SiO2.50FeO.30CaO Glass Ceramic Prepared by the Sol-Gel Method. IJMSE 2023; 20 (2) :1-11
URL: http://ijmse.iust.ac.ir/article-1-3238-en.html

Effect of Heat-Treatment Temperatures on Magnetite Oxidation in 20SiO2.50FeO.30CaO Glass Ceramic Prepared by the Sol-Gel Method

Parisa Rastgoo oskoui

, Mohammad Rezvani

, Abbas Kianvash

Abstract: (7690 Views)

Abstract
The effect of different heat-treatment temperatures on the magnetic, crystallization, and structural properties of 20SiO2.50FeO.30CaO (mol%) glass ceramics was studied. The initial glass was synthesized by the sol-gel method at 25℃ with a precursors to solvent ratio of 1/5. After aging the resulted gel for 24 h at room temperature, it was dried in an electric dryer at 110 ℃ . By heat treatment at different temperatures, different phases such as magnetite, maghemite, and hematite were crystallized in the glass. The maximum stability temperature of magnetite and maghemite were 360℃ and 440℃ respectively. By increasing the heat treatment temperature to higher than 440℃ , the oxidation of maghemite to hematite was occureds. The highest magnetization amount (1.9 emu/g) belonged to sample heat treated at 680℃ . By increasing the heat treatment temperature to 840℃ , the magnetization decreased to 0.8 emu/g, due to the oxidation of maghemite. By increasing the heat treatment temperature from 440℃ to 680℃ , crystalline size of maghemite was increased from 40 to 200 nm. By forther increment of temperature to 840℃ , the size of maghemite crystals decreased to 17nm, due to the oxidation of maghemite to hematite.
Abstract
The effect of different heat-treatment temperatures on the magnetic, crystallization, and structural properties of 20SiO2.50FeO.30CaO (mol%) glass ceramics was studied. The initial glass was synthesized by the sol-gel method at 25℃ with a precursors to solvent ratio of 1/5. After aging the resulted gel for 24 h at room temperature, it was dried in an electric dryer at 110 ℃ . By heat treatment at different temperatures, different phases such as magnetite, maghemite, and hematite were crystallized in the glass. The maximum stability temperature of magnetite and maghemite were 360℃ and 440℃ respectively. By increasing the heat treatment temperature to higher than 440℃ , the oxidation of maghemite to hematite was occureds. The highest magnetization amount (1.9 emu/g) belonged to sample heat treated at 680℃ . By increasing the heat treatment temperature to 840℃ , the magnetization decreased to 0.8 emu/g, due to the oxidation of maghemite. By increasing the heat treatment temperature from 440℃ to 680℃ , crystalline size of maghemite was increased from 40 to 200 nm. By forther increment of temperature to 840℃ , the size of maghemite crystals decreased to 17nm, due to the oxidation of maghemite to hematite.

Keywords: Bioactive Glass-Ceramic, Magnetic properties, Sol-Gel, Hyperthermia, Maghemite