Barium ferrite magnetic properties

Magnetic properties Barium ferrite, iron oxide Ba, Fe... 

Hydrothermal Method. Iron [Fe(III)], barium, and the dopants are precipitated as their hydroxides and reacted with an excess of sodium hydroxide solution (up to 6 mol/L) at 250-350 °C in an autoclave. This is generally followed by an annealing treatment at 750-800°C to obtain products with the desired magnetic properties. Many variations of the process have been described [5.36]-[5.40], the earliest report being from 1969 [5.41], In later processes, hydrothermal synthesis is followed by coating with cubic ferrites, a process resembling the cobalt modification of iron oxides (see Section 5.1.2). The object is to increase the saturation magnetization of the material [5.42]-[5.44],... 

Magnetic Recording Properties. Typical values of physical properties of barium ferrite pigments used in magnetic recording are given in Table 38. 

The flocculating properties of resins from barium ferrite and y-iron oxide are similar. Even diough the magnetized resin is flocculated, the floes break up readily when stirred so that the particles react more rapidly than standard-sized resin beads which are 300-1200 pm in diameter (Fig. 2). The shell configuration of whisker-type resins also enhances reaction r tes. Because of the magnetic flocculation phenomenon the magnetized beads separate out much more rapidly than the unmagnetized ones (Fig. 3). 

Kakizaki, K., and Hiratuka, N., Magnetic properties and crystal structures of acicular barium ferrite particles, J. Magn. Soc. Jpn., 22(suppl. SI), 129, 1998. Lemke, J.U., Ultra high density recording with new heads and tapes, IEEE Trans. Magn., 15, 1561, 1979. 

Barium ferrites do not affect the mechanical properties of natural rubber and hence are useful in magnetic apphcations. Cure rates are increased considerably but ferrites may cause reversion problem. " The magnetic properties increase almost linearly with the amount of ferrite added. 

Kaczmarek, W. A., Ninham, B. W. Calka, A. (1991). Structure and magnetic properties of aerosol synthesized barium ferrite particles. Journal of Applied... 

Pillai, V, Kumar, R, Shah, D.O. Magnetic properties of barium ferrite synthesized using a microemulsion mediated process. J. Magn. Magn. Mater. 116, L299-L304 (1992)... 

PUlai, V, Kumar, P, Multani, M.S., Shah, D.O. Structure and magnetic properties of nanoparticles of barium ferrite synthesized using microemulsion processing. CoU. Surf. A 80, 69-75 (1993)... 

Barium ferrite LICA 38 Thermoplastic natural mbber Improved electrical and magnetic properties [64]... 

Coprecipitation of ferric chloride in excess NaOH and in the presence of barium carbonate forms a mixture of mixed hydroxides and basic carbonates which, upon calcination at 710°C, form the barium ferrite. The magnetic properties are optimized by subsequent heat treament at 950 °C. This method produces plateletshaped particles with an average size of 0.3 pm [110]. Another technique involves oxidation of feirous oxalate by hydrogen peroxide in the presence of excess oxalic acid. The addition of barium carbonate (Ba/Fe = 1/12) forms.mixed complexes of... 

Fu] Fu, YP, Lin, C.H., Pan, K.Y., Fe/Ba Ratio Effect on Magnetic Properties of Barium Ferrite Powders Prepared by Microwave-Induced Combustion , Japan. J. Appl. Phys., 42(5A), 2681-2684 (2003) (Experimental, Magn. Prop., Phase Relations, 13)... 

---