CN101497463A

CN101497463A - Method for preparing gamma-Fe2O3 nanoparticle by two-step precipitation

Info

Publication number: CN101497463A
Application number: CNA2009101033336A
Authority: CN
Inventors: 李建; 高荣礼; 韩芍娜
Original assignee: Southwest University
Current assignee: Southwest University
Priority date: 2009-03-06
Filing date: 2009-03-06
Publication date: 2009-08-05
Anticipated expiration: 2029-03-06
Also published as: CN101497463B

Abstract

The invention provides a method for preparing gamma-Fe2O3 nanoparticles by a two-step precipitation method, which comprises the following steps: 1, a coprecipitation method is adopted to prepare an FeOOH/Mg(OH)2 precursor; and 2, hydroxide precursor is subjected to heat treatment in an FeCl2 solution, and the obtained product is cooled to the room temperature and then precipitates again to produce the gamma-Fe2O3 nanoparticles. The geometric median particle diameter of the gamma-Fe2O3 nanoparticles is around 8nm, and is 70emu/g higher than that of saturated magnetization intensity. The method has the advantages of unique formation mechanism, low cost of raw materials, and easy operation of the preparation process; and the prepared gamma-Fe2O3 nanoparticles are mainly spherical, and have small particle diameters and high saturated magnetization intensity.

Description

The two-step precipitation legal system is equipped with γ-Fe 2O 3The method of nanoparticle

Technical field

The invention belongs to technical field of nano material, be specifically related to ferromagnetic γ-Fe ₂O ₃The preparation of nanoparticle.

Background technology

Particle diameter is that the magnetic nanometer particles of 1～100nm scope is important nano material, wherein γ-Fe ₂O ₃Magnetic nanometer particles is because chemical property is stable, magnetic is strong and be used for biomedicine field (as the separation of mark magnetic carrier, biochemical product, nuclear magnetic resonance contrast-enhancing agent etc.) and other technical field, as high-density magnetic memory device, magnetic cooling system and magnetic liquid.γ-Fe ₂O ₃The technology of preparing of nanoparticle has coprecipitation method, microemulsion method, thermal decomposition method, hydrothermal method and evaporation-condensation method etc.Wherein coprecipitation method be use the most general method, this legal system is equipped with γ-Fe ₂O ₃Its specific saturation magnetization of nanoparticle is about 50emu/g, and how much median particle diameters are about 10nm.

Summary of the invention

The present invention proposes the two-step precipitation legal system and be equipped with γ-Fe ₂O ₃The method of nanoparticle.This method has unique formation mechanism, and material cost is low, the preparation process easy handling.Prepared γ-Fe ₂O ₃Nanoparticle is spherical substantially, and particle diameter is little, the saturation magnetization height.

Preparation method of the present invention is specific as follows:

The first step precipitation: presoma preparation

In alkaline medium, co-precipitation Fe ³⁺-Mg ²⁺The mixture of the aqueous solution is to obtain oxyhydroxide presoma throw out.

(1) FeCl of configuration 2-4M concentration ₃Mg (the NO of the aqueous solution (solution 1), 1-3M concentration ₃) ₂(solution 2 is by every liter of Mg (NO for the aqueous solution ₃) ₂The ratio of 5 moles of HCl of solution adds HCl).Dispose the NaOH aqueous solution (solution 3) of 0.7M concentration in addition

(2) be that 1～3:1 chooses an amount of solution 1 and solution 2 according to Fe, Mg mol ratio, with solution 1 pour into obtain in the solution 2 solution 2 '.Again according to solution 2 ' with the volume ratio of solution 3 be that 1:10 chooses an amount of solution 3.Under agitation solution 2 ' pour into is fast obtained in the solution 3 solution 3 '.

(3) heated solution 3 ' extremely boiling under agitation.Keep boiling 1 minute, stop heating then, naturally cool to room temperature.After 1 hour, precipitation of hydroxide is come out.

(4) outwell clear liquid, stay throw out.With 0-0.01M HNO ₃The aqueous solution repeatedly cleans, to pH=7～8.

The second step precipitation: produce γ-Fe ₂O ₃Particulate

(1) FeCl of configuration 0.1-0.5M concentration ₂The aqueous solution (solution 4)

(2) oxyhydroxide that the first step precipitation is obtained is poured in the solution 4, gets solution 5, and the volume ratio of throw out and solution 4 is 1:10;

(3) under agitation heated solution 5 to boiling.Keep boiling 5～60 minutes, stop heating then, be cooled to room temperature.After 1 hour, new throw out-γ-Fe ₂O ₃Particulate produces.

(4) clean three times with distilled water.

(5) with acetone dehydration, drying, make γ-Fe ₂O ₃Nanoparticle.

Prepared γ-Fe ₂O ₃The particle diameter of nanoparticle is at 3-18nm, and specific saturation magnetization is higher than 70emu/g.

Present method material cost is low, the preparation process easy handling, prepared γ-Fe ₂O ₃Nanoparticle is spherical substantially, and particle diameter is little, the saturation magnetization height.

Description of drawings

Fig. 1 is that this law prepares γ-Fe ₂O ₃The transmission electron microscope image of particulate

Fig. 2 is the γ-Fe of this law preparation ₂O ₃The magnetzation curve of nanoparticle

Embodiment one:

One, precipitate for the first time: coprecipitation method prepares presoma

1. the configuration of solution

(1) solution 1.: FeCl ₃The aqueous solution (40ml, 1mol/L)

(2) solution 2.: Mg (NO ₃) ₂(10ml, 2mol/L), other adds the HCl of 0.05mol to the aqueous solution

(3) solution is 3.: and the NaOH aqueous solution (500ml, 0.7mol/L)

2. mix

(1) solution 1. pour into solution obtain in 2. solution 2. '

(2) solution 3. pour into solution 2. ' obtain solution 3. '

3. reaction

(1) with solution 3. ' on electric furnace, be heated to boiling, do not stop in the heat-processed to stir.

(2) boiling was taken off from process furnace after 5 minutes, naturally cooling, and the reddish-brown precipitation that engenders in the process of cooling, postprecipitation finished in about 2 hours.

4. clean

(1) scavenging solution configuration

0.01mol/L HNO ₃The aqueous solution

(2) clean

Mix for the 1:5 ratio with scavenging solution volume ratio in throw out, fully stir ((1～1.2) * 10 of centrifugation then ³Rev/min).After outwelling upper clear supernate, add scavenging solution more equally and clean.Repeated multiple times is until PH～7-8.

Two, precipitate for the second time: FeCl ₂Processing of Preparation γ-Fe ₂O ₃Nanoparticle

1. solution preparation

Solution is 4.: FeCl ₂The aqueous solution (400ml, 0.25mol/L)

2. mix

4. the throw out that obtains in the settling step first time is mixed with solution, obtain solution 5.

3. reaction

(1) 5. solution is heated to boiling on electric furnace, keeps boiling 30 minutes.Keep uninterrupted the stirring therebetween.

(2) take off naturally cooling from electric furnace.Engender black precipitate in the process of cooling.

4. clean

Clean three times with distilled water

5. dry

(1) be that sedimentary 4～5 times acetone mixes with volume, centrifugation is dewatered then, and this step repeats 2～3 times.

(2) dewatered product is changed in the moisture eliminator.Can obtain anhydrous exsiccant γ-Fe after 24 hours ₂O ₃Particulate

Embodiment two:

One, precipitate for the first time: coprecipitation method prepares presoma

Identical with embodiment one.

1. solution preparation

Solution is 4.: FeCl ₂The aqueous solution (400ml, 0.5mol/L)

2-5 is identical with embodiment one.

Embodiment three:

One, precipitate for the first time: coprecipitation method prepares presoma

Identical with embodiment one.

1-2 is identical with embodiment one.

3. reaction

(1) 5. solution is heated to boiling on electric furnace, keeps boiling 45 minutes.Keep uninterrupted the stirring therebetween.

4-5 is identical with embodiment one.

The form of particulate and particle diameter

The form that obtains particulate with transmission electron microscope is spherical substantially, as shown in Figure 1.By analysis, diameter of particle is lognormal distribution, how much median particle diameter d _gBe 7.9nm, distribution bias ln σ _gBe 0.29.

The specific magnetising moment of particulate

Carry out the measurement of the specific magnetising moment with vibrating sample magnetometer, obtained the magnetzation curve of specific magnetization σ and magnetic field H relation, as shown in Figure 2, by analysis, its specific saturation magnetization σ _sBe 75emu/g.

Claims

1. the two-step precipitation legal system is equipped with γ-Fe ₂O ₃The method of nanoparticle comprises following two steps:

The first step: presoma preparation

In alkaline medium, co-precipitation Fe ³⁺One Mg ²⁺The mixture of the aqueous solution, to obtain oxyhydroxide presoma throw out:

(1) FeCl of configuration 2-4M concentration ₃The aqueous solution, ie in solution 1; Mg (the NO of configuration 1-3M concentration ₃) ₂The aqueous solution, ie in solution 2, and by every liter of Mg (NO ₃) ₂The ratio of 5 moles of HCl of solution adds HCl; Dispose the NaOH aqueous solution of 0.7M concentration in addition, ie in solution 3;

(2) be that 1～3:1 chooses solution 1 and solution 2 according to Fe, Mg mol ratio. with solution 1 pour into obtain in the solution 2 solution 2 '; Again according to solution 2 ' with the volume ratio of solution 3 be that 1:10 chooses solution 3, under agitation solution 2 ' pour into is fast obtained in the solution 3 solution 3 ';

(3) under agitation heated solution 3 ' to boiling, maintenance boiling 1 minute stops heating then, naturally cools to room temperature, and after 1 hour, precipitation of hydroxide is come out;

(4) outwell clear liquid, stay throw out, use HNO ₃The aqueous solution repeatedly cleans, to pH=7～8;

Second step: γ-Fe ₂O ₃Nanoparticle forms

(1) FeCl of configuration 0.1 1 0.5M concentration ₂The aqueous solution, ie in solution 4

(2) oxyhydroxide that the first step precipitation is obtained is poured in the solution 4, gets solution 5; The volume ratio of throw out and solution 4 is 1:10;

(3) under agitation heated solution 5 keeps boiling 5～60 minutes to boiling, stops heating then, is cooled to room temperature, after 1 hour, and new throw out-γ-Fe ₂O ₃Particulate produces;

(4) throw out that (3) are obtained cleans with distilled water, with acetone dehydration, drying, makes γ-Fe again ₂O ₃Nanoparticle.

2. two-step precipitation legal system according to claim 1 is equipped with γ-Fe ₂O ₃Nanoparticle, its characteristics are prepared γ-Fe ₂O ₃The particle diameter of nanoparticle is at 3-18nm, and specific saturation magnetization is higher than 70emu/g.