CN1116976A - Lasser gas-phase synthesis of gamma ferric oxide nanometer micropowder - Google Patents

Abstract

The prepn techn of superfine Gamma-Fe2O3 powder uses SF6 or C2H4 as photosensitive gas and uses Fe(CO)5 as iron source. The photosensitive gas is passed through iron source at 30-70 deg.C and enters laser reaction chamber of argon or nitrogen atmosphere. Under the action of continuous CO2 laser beam, gaseous pyrolysis produces Alpha-Fe powder which is then oxidized in the atmosphere containing 5-20% oxygen at 200-400 deg.C for 20-40 min. The present invention can produce high pure and homogeneous superfine nanon-grade Gamma-Fe2O3 powder.

Description

The Lasser gas-phase synthesis of gamma ferric oxide nano powder

The present invention's step and γ-Fe ₂O ₃The synthetic α of technology of preparing, particularly laser Gaseous-Fe micro mist, generate γ-Fe through oxidation processes again ₂O ₃The technology of nano powder.

γ-Fe ₂O ₃Micro mist is the most a kind of magnetic recording material of using in the present industry, has good stability, and the characteristics such as excellent magnetic are processed by mixing Co, Ni etc. and coating in addition, can increase substantially its magnetic property.Manufacture γ-Fe in the at present industry ₂O ₃Method, at first be that its crystalline state is aciculiform, becomes α-Fe after the dehydration with the artificial synthetic iron oxide yellow (alpha-feooh) of chemical method ₂O ₃, after reduction, oxidation, form γ-Fe ₂O ₃Needle-shaped particle, it is of a size of 200～800nm, mix on this basis other metals such as the elements such as Co, Ni, with the raising coercivity, this method complex process, the production cycle is long, the cost height.

The object of the present invention is to provide a kind of production technology simple, and the product purity height, the tiny uniform γ-Fe of granularity ₂O ₃The nano powder synthetic method.

The invention provides a kind of γ-Fe ₂O ₃The technology of preparing of ultrafinepowders is characterized in that: this method is finished through two steps of oxidation with the synthetic α of laser Gaseous-Fe micro mist again, and technical process and parameter are as follows:

(1) α-Fe micro mist forms:

---with SF ₆Or C ₂H ₄Make photosensitive gas;

---with Fe (CO) ₅Make source of iron;

---photosensitive gas enters into the laser reactive chamber of argon gas or blanket of nitrogen, at continuous CO by being heated to 30～70 ℃ source of iron ₂Under the laser beam effect, the vapour-phase pyrolysis reaction generates α-Fe, and the technology ginseng is imitated and is:

Laser power density: 500～5000W/cm ²

Chamber pressure: 0.2～0.8atm

Photosensitive gas velocity: 20～100ml/min

(2) particulate oxide:

Above-mentioned α-Fe micro mist in the atmosphere of oxygen level 5～20wt% under 200～400 ℃, oxidation 20～40 minutes.

The present invention is because 1) use CWCO ₂Laser is at sensitising agent C ₂H ₄Or SF ₆Effect is lower, brings out Fe (CO) ₅Pyrolytic reaction, prepare nanometer α-Fe particle, have high-purity, ultra-fine (10～50nm), the feature such as particle size distribution is even, and particle connects to chain, favourable to improving magnetic property.2) by control oxidizing atmosphere and oxidizing temperature, with the basic powder of α-Fe, oxidation generates γ-Fe ₂O ₃Change of granularity before and after the nano powder, oxidation is very little, and distribution characteristics is constant.This kind γ-Fe ₂O ₃Particulate mostly is single domain particle, has more excellent magnetic recording property.Below by embodiment in detail the present invention is described in detail.

The principle of device synoptic diagram of accompanying drawing 1 during for the synthetic α of laser Gaseous-Fe particle;

Accompanying drawing 2 is the γ-Fe of preparation ₂O ₃The nanometer powder shape appearance figure.

Embodiment 1

At first with the synthetic α of laser vapor phase method-Fe micro mist, device is seen Fig. 1, source of iron Fe (CO) ₅Be placed in one jar (1); photosensitive gas is taken away source of iron and is entered into reaction chamber (2) by jar (1); laser beam focuses on the reaction gas flow place; under the reaction gas flow corresponding to a collection tube (3); collection tube (3) links to each other with vacuum pump by a strainer (4); relative with laser beam inlet eyeglass (5) is laser absorption sheet (6), and eyeglass (5) nearby is protection gas inlet, can feed argon gas or nitrogen with the protection eyeglass.

The preset parameter of reactor is: nozzle diameter 3mm, focus point be the 3.5mm place below nozzle region, spot diameter 5mm.

With SF ₆Make sensitising agent, flow velocity is 40ml/min, laser power 300W, source of iron is heated to 30 ℃, chamber pressure 0.4atm prepares particle diameter and is the α of 20～30nm-Fe particulate, then with α-Fe at the N that contains air 20～30% ₂Middle oxidation, 250 ℃ of temperature, time 30min can obtain chain γ-Fe ₂O ₃The nanopowder pattern see Fig. 2.

Embodiment 2

α-Fe prepares the same, with α-Fe passivation in containing the inert gas of a small amount of air, forms earlier the iron oxide film on its surface, is containing 5～15%O then ₂N ₂In oxidation, temperature is 300 ℃, time 20min can obtain the γ-Fe of chain form equally ₂O ₃Ultramicron.

Claims (2)

1. γ-Fe ₂O ₃The technology of preparing of ultrafinepowders is characterized in that: this method is finished through two steps of oxidation with the synthetic α of laser Gaseous-Fe micro mist again, and technical process and parameter are as follows:

(1) α-Fe micro mist forms:

---with SF ₆Or C ₂H ₄Make photosensitive gas;

---with Fe (CO) ₅Make source of iron;

---photosensitive gas enters into the laser reactive chamber of argon gas or blanket of nitrogen, at continuous CO by being heated to 30～70 ℃ source of iron ₂Under the laser beam effect, the vapour-phase pyrolysis reaction generates α-Fe, and the technology ginseng is imitated and is:

Laser power density: 500～5000W/cm ²

Chamber pressure: 0.2～0.8atm

Photosensitive gas velocity: 20～100ml/min

(2) particulate oxide:

Above-mentioned α-Fe micro mist in the atmosphere of oxygen level 5～20% under 200～400 ℃, oxidation 20～40 minutes.

2. by the described γ-Fe of claim 1 ₂O ₃The technology of preparing of powder is characterized in that: slowly pass into air earlier before the micro mist oxidation and carry out passivation.

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