IRON-BASED NANOPARTICLES AND METHODS OF PROCESSING
Methods and compositions including iron-based nanoparticles are provided herein. A method of processing an iron-based nanoparticle to form a capped iron-based nanoparticle may include introducing a cation and introducing an anion. The cation may bond to a portion of an outer region of the iron-based nanoparticle to define an intermediate nanoparticle. The anion may react with the intermediate nanoparticle to form a cation-anion coating, or a shell, on one or more portions of the outer region of the intermediate nanoparticle to form an iron-based capped nanoparticle. The cation-anion coating may cover only a portion of the outer region.
1 . A method comprising:
introducing a cation to an iron-based nanoparticle having an outer region, the cation bonding to a portion of the outer region and defining an intermediate nanoparticle; and
introducing an anion to the intermediate nanoparticle, the anion reacting with the intermediate nanoparticle to form a cation-anion coating on one or more portions of the outer region of the intermediate nanoparticle to form an iron-based capped nanoparticle.
2 .- 10 . (canceled)
11 . A method comprising:
suspending iron-based nanoparticles in a fluid;
exposing the iron-based nanoparticles to a cation to form a mixture;
mixing the mixture; and
exposing the mixture to an anion such that the anion reacts with the cation to form a precipitate on a portion of an outer region of the iron-based nanoparticle to form a capped nanoparticle.
12 .- 16 . (canceled)
17 . A composition comprising:
an iron-based nanoparticle having an outer region; and
a shell covering at least a portion of the outer region, the shell including a cation-anion pair.
18 . The composition of claim 17 , wherein the iron-based nanoparticle has a mean aggregate size of less than 2 microns.
19 . The composition of claim 17 , wherein the iron-based nanoparticle has a size of approximately 5 nanometers or greater.
20 . The composition of claim 17 , wherein the iron-based nanoparticle has a size of approximately 40 nanometers or less.
21 . The composition of claim 17 , wherein the cation-anion pair includes a metal cation including at least one of an alkali metal, an alkaline earth metal, or a transition metal.
22 . The composition of claim 17 , wherein the cation-anion pair includes an anion including at least one of an oxide, hydroxide, and a carbonate.
23 . The composition of claim 17 , wherein the cation-anion pair includes at least one of ammonium carbonate, sodium carbonate, ammonium hydroxide, sodium hydroxide, trisodium phosphate, manganese hydroxide (Mn(OH) 2 ), manganese dioxide (MnO 2 ), or ammonium phosphate.
24 . The composition of claim 17 , wherein the cation-anion pair includes a chloride.
25 . The composition of claim 17 , wherein the shell covers 99% or less of the outer region of the iron-based nanoparticle.
26 . The composition of claim 17 , wherein the iron-based nanoparticle includes iron oxide.
27 . The composition of claim 26 , wherein the iron oxide includes any of Fe 3 O 4 or Fe 2 O 3 .
28 . A composition comprising:
an iron-based nanoparticle having an outer region including a grain boundary; and
an insoluble precipitate attached to at least a portion of the grain boundary, wherein 99% or less of the grain boundary is covered by the insoluble precipitate.
29 . The composition of claim 28 , wherein the insoluble precipitate includes at least one of an insoluble hydroxide or insoluble carbonate.
30 . The composition of claim 28 , wherein the iron-based nanoparticle includes iron oxide.
31 . The composition of claim 30 , wherein the iron oxide includes any of Fe 3 O 4 or Fe 2 O 3 .
32 . The composition of claim 28 , wherein the insoluble precipitate includes a cation-anion pair.
33 . A mixture comprising:
at least one iron-based nanoparticle having an outer region; and
an anion-cation pair bonded to a first portion of the outer region,
wherein a second portion of the outer region is uncovered by the anion-cation pair.
34 . The mixture of claim 33 , wherein the iron-based nanoparticle has a size of approximately 5 nanometers or greater.
35 . The mixture of claim 33 , wherein the iron-based nanoparticle has a size of approximately 40 nanometers or less.
36 . The mixture of claim 33 , wherein the anion-cation pair cover 99% or less of the outer region of the iron-based nanoparticle.