A Study of Magnetic Properties of Coprecipitated NiAl Ferrite

• Main Authors: Chen, Zhong-Ren, 陳中仁
• Other Authors: Chang Yen-Hwei
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/31762052161109175737

碩士 === 國立成功大學 === 材料科學(工程)學系 === 84 === Ferrite is a complexing compound, its major composition is Fe2O3. Ferrite can change its intrinsic magnetic intensity by adding or substituting M2+, for example, Ni2+, Mn2+, Mg2+, Co2+, Cu2+ and Zn2+ etc. Nickel ferrite is one of the earlier discovered ferrite. It has the inverse spinel type structure. It has some important properties, for example, high Curie temperature(about 570℃) and high electroresistance factor(＞10E8Ω-cm). But it has defects, like higher loss and lower squarness ratio,too. The coprecipitated Nickle Ferrite-Aluminate powders by hydroxide method has been investigated. Sodium hydroxide was used as precipitant, and the coprecipitated powders were prepared at room temperature in a solution of pH=9 by titration with a constant rate. The particle size of the precipitated powders were uniform with a distribu- tion between 0.3 and 0.5 micrometer. From the experimental result, it was found that the increase of Al content decreased the magnetization and the permeability of the ferrites , but the coer- cive force was increased. Rising the sintering temperature, the magnetization and permeability increase, but the coercive force decreased. After sintering at 1350℃ to 4 hours, the ferrite NiAl0.05Fe1.95 O4, possesses best densitification and better properties . The addition of Bi2O3 could reduce the sintering temperature by 100℃. For example, the sample, NiAl0.05Fe1.95O4, sintered at 1250℃ for 8 hours, has better properties than that of discussed before.