Magnetic Fluids :: GCSE Chemistry

1.1 PRELUDEThe phenomenon of ferromagnetism is associated only with the substantialness state of function like iron, nickel, cobalt and some rare earth metals and their eachoys. Thus, up to now, at that place is no intrinsic homogeneous fluid having ferro magnetic properties although, theories admit the opening of ferromagnetism in the liquid state, and suggest that there is no inherent origin why they should not exist 1-3,5. Ferromagnetism occurs when paramagnetic ions in a solid lock together in such a way that their spins all intimate (on the average) in the same direction . At a real temperature this locking breaks down and ferromagnetic reals become paramagnetic. This transition temperature is called the Curie point (TC), which is invariably well below the melting point of the corresponding material 1,8,12.1.2 MAGNETIC FLUIDSMagnetic fluids ( MF ) are stable colloidal suspensions of ultra exquisitely ferro- or ferri- magnetic particles ( D100Ao ), coated with a surfacta nt like oleic acid, in a suitable liquid carriers such as Isopar-M, kerosene, decalin, etc., 1,2. The idea of MF was depute forward independently and almost simultaneously by several investigators. The low prepared MF was developed by Stephen Papell of the National Aeronautics and set Administration (NASA) in the early 1960s. After that, Ronald E. Rosensweig and his colleagues succeeded in formulating MFs that were 10 quantify as strong magnetically as Papells original MF 1.The special feature of magnetic fluids is given by the fact, that they combine linguistic rule liquid behavior with superparamagnetic properties, as will be discussed later. The possibility of magnetic fluid control gave rise to the development of many technical applications in our everyday life 1-3.Mixtures are classified into three kinds colloidal suspensions, suspensions, and solutions, and unity of the principal features that differentiate one kind of mixture from another is the size of it of the parti cles 6. Colloidal suspensions (also called colloids) are mixtures that are intermediate between solutions and suspensions. Typically the rung of the particle is of the order 100Ao. Since this is much smaller than the size of a maven magnetic domain in bulk solids, which is about , the magnetization of the private particle is saturated, but the direction of the magnetic moment is subject to thermal agitation 1,2,5. The particles used are commonly Fe3O4, Fe, Co and Ni.MF is a two-phase system with three components, which combines magnetic properties, carried by the solid magnetic fine particles, with fluidity of the carrier liquid.