A method of controlling the electrical properties of a quantity of magnetite particles comprises the step of oxidising at least some of the quantity of magnetite particles by heating the said quantity of magnetite particles in an oxygen rich environment for a period of time.

A method of controlling the electrical properties of a quantity of magnetite particles comprises the step of oxidising at least some of the quantity of magnetite particles by heating the said quantity of magnetite particles in an oxygen rich environment for a period of time.

[Problem]

A novel method for producing a nanoparticle having a metal particle which contains iron oxide to which one or more hydrophilic ligands are coordination bonded is provided, where the nanoparticle is useful as a contrast agent for magnetic resonance imaging.

[Means for Solution]

As the novel method for producing a nanoparticle having a metal particle which contains iron oxide to which one or more hydrophilic ligands are coordination bonded, by performing ligand exchange to a hydrophilic ligand from an iron oxide nanoparticle having a surface to which a hydrophobic ligand is coordination bonded in one step using a phase transfer catalyst, it is possible to expect shortening of production processes and reduction of hydrophilic ligands used.

Furthermore, by producing an iron oxide nanoparticle having a surface to which a hydrophobic ligand is coordination bonded using a dropwise addition method, it is possible to avoid a rapid temperature rise and a reaction at a high temperature of 200° C. or higher, which is more advantageous for industrial production.

[Problem]

A novel method for producing a nanoparticle having a metal particle which contains iron oxide to which one or more hydrophilic ligands are coordination bonded is provided, where the nanoparticle is useful as a contrast agent for magnetic resonance imaging.

[Means for Solution]

As the novel method for producing a nanoparticle having a metal particle which contains iron oxide to which one or more hydrophilic ligands are coordination bonded, by performing ligand exchange to a hydrophilic ligand from an iron oxide nanoparticle having a surface to which a hydrophobic ligand is coordination bonded in one step using a phase transfer catalyst, it is possible to expect shortening of production processes and reduction of hydrophilic ligands used.

Furthermore, by producing an iron oxide nanoparticle having a surface to which a hydrophobic ligand is coordination bonded using a dropwise addition method, it is possible to avoid a rapid temperature rise and a reaction at a high temperature of 200° C. or higher, which is more advantageous for industrial production.

Magnetic beads comprise a plurality of magnetic nanoparticles, dispersed in a non-magnetic matrix. The magnetic beads have an average particle size of 0.1 μm to 100 μm. The matrix may comprise an inorganic metal oxide or a polymer. The magnetic beads have a specific surface area of at least 40 m.sup.2/g.

Magnetic beads comprise a plurality of magnetic nanoparticles, dispersed in a non-magnetic matrix. The magnetic beads have an average particle size of 0.1 μm to 100 μm. The matrix may comprise an inorganic metal oxide or a polymer. The magnetic beads have a specific surface area of at least 40 m.sup.2/g.

A method of purifying a plurality of metal oxide particles produced from a synthesis process comprising the step of washing a plurality of metal oxide particles in a first solvent composition comprising of at least one aliphatic ether, and at least one flocculant. In one embodiment, the plurality of metal oxide particles are iron oxide particles produced from a thermal decomposition synthesis process between an iron-oleate complex and oleic acid in 1-octadecene, wherein the first solvent composition comprises a 1:1 (vol/vol) ratio of an aliphatic ether in the form of diethyl ether and a flocculant in the form of methanol. The washed iron oxide particles are further washed in a second solvent composition comprising a 1:1 (vol/vol) ratio of hexane and ethanol, and then finally dispersed in hexane. The resulting iron oxide particles find use as a contrast agent for magnetic resonance imaging (MRI) or as magnetic particles in magnetic separation, magnetism-directed targeting or magnetism-induced heating.

A method of purifying a plurality of metal oxide particles produced from a synthesis process comprising the step of washing a plurality of metal oxide particles in a first solvent composition comprising of at least one aliphatic ether, and at least one flocculant. In one embodiment, the plurality of metal oxide particles are iron oxide particles produced from a thermal decomposition synthesis process between an iron-oleate complex and oleic acid in 1-octadecene, wherein the first solvent composition comprises a 1:1 (vol/vol) ratio of an aliphatic ether in the form of diethyl ether and a flocculant in the form of methanol. The washed iron oxide particles are further washed in a second solvent composition comprising a 1:1 (vol/vol) ratio of hexane and ethanol, and then finally dispersed in hexane. The resulting iron oxide particles find use as a contrast agent for magnetic resonance imaging (MRI) or as magnetic particles in magnetic separation, magnetism-directed targeting or magnetism-induced heating.

Disclosed is a method and system for recovering at least rare earth elements from within an object A consisting of at least one first rare earth portion or a mixture of rare earth elements and a second metal portion. The method includes a solvothermal treatment step that places the object in contact with a fluid for causing at least one rare earth portion and/or mixture of rare earth elements and the metal portion to oxidize in order to separate same, the value of the reaction temperature Tr is selected according to the nature of the object, the reaction following a R-M.fwdarw.R(X)x+M(X)y scheme, where R is the rare earth element or a mixture of rare earth elements, M is the transition metal, and (X) is a group which depends on the fluid used.

Disclosed is a method and system for recovering at least rare earth elements from within an object A consisting of at least one first rare earth portion or a mixture of rare earth elements and a second metal portion. The method includes a solvothermal treatment step that places the object in contact with a fluid for causing at least one rare earth portion and/or mixture of rare earth elements and the metal portion to oxidize in order to separate same, the value of the reaction temperature Tr is selected according to the nature of the object, the reaction following a R-M.fwdarw.R(X)x+M(X)y scheme, where R is the rare earth element or a mixture of rare earth elements, M is the transition metal, and (X) is a group which depends on the fluid used.