Ferrofluid
<p><font size="3">A <b>ferrofluid</b> (from the Latin <i><a class="extiw" title="wiktionary:ferrum" href="http://en.wiktionary.org/wiki/ferrum">ferrum</a></i>, meaning iron) is a liquid which becomes strongly polarised in the presence of a </font><a title="Magnetic field" href="http://en.wikipedia.org/wiki/Magnetic_field"><font size="3">magnetic field</font></a><font size="3">.</font></p><p><font size="3">Ferrofluids are composed of </font><a title="Nanoscale" href="http://en.wikipedia.org/wiki/Nanoscale"><font size="3">nanoscale</font></a><font size="3">
</font><a title="Ferromagnetic" href="http://en.wikipedia.org/wiki/Ferromagnetic"><font size="3">ferromagnetic</font></a><font size="3"> particles suspended in a </font><a class="extiw" title="wiktionary:carrier" href="http://en.wiktionary.org/wiki/carrier"><font size="3">carrier</font></a><font size="3">
</font><a title="Fluid" href="http://en.wikipedia.org/wiki/Fluid"><font size="3">fluid</font></a><font size="3">, usually an organic solvent or water. The ferromagnetic nano-particles are coated with a </font><a title="Surfactant" href="http://en.wikipedia.org/wiki/Surfactant"><font size="3">surfactant</font></a><font size="3"> to prevent their agglomeration (due to </font><a title="Van der Waals force" href="http://en.wikipedia.org/wiki/Van_der_Waals_force"><font size="3">van der Waals</font></a><font size="3"> and magnetic forces). Although the name may suggest otherwise, ferrofluids do not display </font><a title="Ferromagnetism" href="http://en.wikipedia.org/wiki/Ferromagnetism"><font size="3">ferromagnetism</font></a><font size="3">, since they do not retain magnetisation in the absence of an externally applied field. In fact, ferrofluids display </font><a title="Paramagnetism" href="http://en.wikipedia.org/wiki/Paramagnetism"><font size="3"><i>para</i>magnetism</font></a><font size="3">, and are often referred as being "superparamagnetic" due to their large </font><a title="Magnetic susceptibility" href="http://en.wikipedia.org/wiki/Magnetic_susceptibility"><font size="3">magnetic susceptibility</font></a><font size="3">. Truly ferromagnetic fluids are difficult to create at present, requiring high temperatures and electromagnetic levitation.</font></p>[attach]6424[/attach]<br/>
