Barium hexaferrite

Shafi KVPM, Felner I, Mastai Y, Gedanken A (1999) Olympic ring formation from newly prepared barium hexaferrite nanoparticle suspension. J Phys Chem B 103 3358-3360... 

Steier, H.P. Requema, J. Moya, J.S. (1999) Transmission electron microscopy study of barium hexaferrite formation from barium carbonate and hematite. J. Mat. Res. 14 3647-3652... 

Fig. 9.33 Microstructure of an oriented barium hexaferrite. (Courtesy of Philips Technical Review.)...

Fig. 9.34 Demagnetization curves for an oriented barium hexaferrite (curve A) and an isotropic hexaferrite (curve B).

Fig. 9.35 The dependence of coercivity on the particle size of a barium hexaferrite powder.

Ataie, A. et al. (1995) Effect of hydrothermal synthesis environment on the particle morphology, chemistry and magnetic properties of barium hexaferrite, J. Mater. Sci., 30, 5600-6. 

Favre A, et al. Catalytic combustion of methane over barium hexaferrites. Catal Lett. 1998 49(3—4) 207—11. 

Plate 13—Lattice image of MYMYe intergrowth phase in the barium hexaferrite system (from ref. 92). 

Femandes-Rodriges, Morales, Tirado synthesized mechanochemically lithium ferrite and lithium cobaltite from lithium hydroxide and corresponding oxihydroxide 5-FeOOH or CoOOH [37]. Similarly, barium hexaferrite BaFei20i9, including that doped with titanium and cobalt, was obtained from Ba(0H)2-H20 and y-FeOOH [38]. 

Barium hexaferrite. Barium hexaferrite, BaFei20 <<, is used as a ceramic permanent magnet. It is conventionally prepared by firing an appropriate mixture of a-Fe203 with BaCOs at high temperatures (1150-1250°C). To reduce the particle size, thus obtained ferrite should be ground. 

The ferromagnetic material barium hexaferrite, BaFe Oig, also known as BaM, is an important component in permanent magnets [270], It can be prepared by the MOCVD of a mixture of [Ba(thd)2]4 (thd" 7) and ferrocene, Cp2Fe [273]. 

Table 2.8. Cation substitutions in barium hexaferrite M Fei2-yB y 0ig.

Lacroix, E., Gerard, P., Marest, G. Dupuy, M. (1991). Substrate effects on the crystalline orientation of barium hexaferrite films. Journal of Applied Physics, 69, 4770-2. 

Stablein, H. Willbrand, J. (1972). Texture and reaction mechanism in the formation of barium hexaferrite. In Proceedings of the Seventh International Symposium on the Reactivity of Solids, Bristol, July 1972. Eds J. S. Anderson, M. W. Roberts and F. S. Stone. Chapman Hall, London, pp. 589-97. 

Yuan, M. S., Glass, H. L. Adkins, L. R. (1988). Epitaxial barium hexaferrite on sapphire, by sputter deposition. Applied Physics Letters, 53, 340-1. 

K. Watanabe and K. Hoshi, Crystallisation Kinetics of Fine Barium Hexaferrite, BaFei20i9, Particles in a Glass Matrix, Phys. Chem. Glasses 40, 75-78 (1999). 

Synonyms Barium ferrate Barium hexaferrite Barium iron oxide... 

Barium hexaferrite. See Barium ferrite Barium hexafluorosilicate Barium hexafluorosilicate (2-). See Barium fluosilicate Barium hydroxide. See Barium hydroxide lime Barium hydroxide lime CAS 17194-00-2 (anhyd.) 12230-71-6 (octahydrate) EINECS/ELINCS 241-234-5 Synonyms Barium dihydroxide Barium hydroxide Caustic baryta Definition Mixt. of barium hydroxide octahydrate and calcium hydroxide Empirical BaH202 Formula Ba(OH)2... 

Ataie, A., Heshmati-Manesh, S., Kazempour, H. Synthesis of barium hexaferrite by the coprecipitation method using acetate precursor. J. Mater. Sci. 37, 2125-2128 (2002)... 

Pillai etal. [301] reported synthesis of barium hexaferrite (BaFei20i9) via a two-microemulsion process. The surfactant used was CTAB with 1-butanol as a co-surfactant, and n-octane as the continuous oil phase. The aqueous phases in the two microemulsions were (i) a solution of 0.0IM Ba(N03)2 and 0.12M Fe(N03)3 and (ii) a 0.19M solution of (NH4)2C03. The microemulsions were mixed under constant stirring, leading to the precipitation of barium iron carbonate. The precipitate was washed with 1 1 methanol and chloroform, followed by only methanol and dried at 100°C. The dried carbonate thus obtained was calcined at 950°C/12h for obtaining a phase-pure barium hexaferrite. However, the Fe Ba ratio was found to be slightly more than the stoichiometric, because of preferential dissolution of barium carbonate in water. As a result, the samples also contained some amorphous iron oxide impurities. The precursor particles had a size range... 

Fig. 3.5. TEM micrograph showing rings of barium hexaferrite nanocrystals. The rings intersect with each other forming Olympic rings. The scale bar is 0.7jim (reproduced with permission from [408])...

Aguas, M.D., Affleck, L., Parkin, I.P., Kuznetsov, M.V., Steer, W.A., Pankhurst, QA Femfindez-Barqufn, L Roberts, MA Boamfti, M.I., and Perenboom, JA.A.J. (2000) The effect of large magnetic fields on solid state combustion reactions novel microstructure, lattice contraction and reduced coercivity in barium hexaferrite. /, Mater. Chem, 10, 235-237. 

Ataie A, Zojaji SE (2007) Synthesis of barium hexaferrite nanoparticles via a mechano-combustion rroute. J Alloys Comp 431 331-336... 

In this chapter, first the ionic reaction equilibrium, phase behavior, and solubility of metal oxides in supercritical water are discussed. Next, the specific features of hydrothermal synthesis under supercritical conditions are discussed based on the experimental results. The supercritical hydrothermal crystallization method was applied to the production of functional materials, barium hexaferrite (BaFei20i9), metal-doped oxide [Al5(Y- -Tb)30i2, YAG Tb], and Li ion battery cathode material (LiC02O4). The importance of understanding the chemical reaction equilibrium and phase behavior is discussed. 

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