Superparamagnetic solid particles
AssigneeBASF SE
InventorsGunther Mair, Werner Steck
Life of this patent
Estimating the term…
Abstract
Superparamagnetic solid particles of the general formula I M.sub.v Mn.sub.w Zn.sub.x Fe.sub.y O.sub.z (I) where M is Co and/or Ni, v and w are each from 0 to 0.998, x is from 0.001 to 0.998, y is from 2.001 to 2.998, z is from 3.001 to 4, v+w+x is from 0.002 to 0.999, v+w+x+y is 3, v.noteq.0 if w=0 and w.noteq.0 or v=0, polar and nonpolar superparamagnetic liquids which contain the surfactant-coated superparamagnetic solid particles I in the form of a colloidal dispersion in polar or nonpolar liquid media, and processes for the preparation of polar and nonpolar superparamagnetic liquids.
Claims4
Superparamagnetic cubic ferrite particles of the formula
- M.sub.v Mn.sub.w Zn.sub.x Fe.sub.y O.sub.z (I)
- where M is selected from the group consisting of Co and Ni, v and w are each from 0 to 0.998, x is from 0.001 to 0.998, y is from 2.001 to 2.998, z is from 3.001 to 4, v+w+x is from 0.001 to 0.999, v+w+x+y is 3, v.noteq.0 if w=0, and w.noteq.0 if v=0;
- having a BET inner surface area of from 40 to 130 m.sup.2 /g and a saturation magnetization M.sub.s of larger than 60 nTm.sup.3 /g in a magnetic field of 160 kA/m, said particles displaying a hysteresis-free reversible magnetization and demagnetization behavior when dispersed colloidally in a liquid.
Dependencies are inferred from the claim text.