CN103204546A

CN103204546A - Method for preparing nano cobalt ferrite

Info

Publication number: CN103204546A
Application number: CN2013101335309A
Authority: CN
Inventors: 张旭东
Original assignee: Lanzhou University
Current assignee: Lanzhou University
Priority date: 2013-04-17
Filing date: 2013-04-17
Publication date: 2013-07-17
Anticipated expiration: 2033-04-17
Also published as: CN103204546B

Abstract

The invention discloses a method for preparing nano-powder of nano cobalt ferrite (CoFe2O4) with a spinel structure at a low temperature. The preparation method comprises the steps of weighing ferric trichloride and cobaltous chloride in proportion, and mixing to prepare water solution A; evenly mixing the prepared NaOH or HOK aqueous alkali, and then dropwise adding N2H4.H2O to obtain solution B; rapidly stirring the water solution A obtained in the step 1 at 20-40 DEG C, and slowly dropwise adding the mixed solution B prepared in the step 2 into the water solution A to react, so as to obtain cobalt ferrite (CoFe2O4) powder sediment with a black spinel structure.

Description

A kind of method for preparing the nanometer vectolite

Technical field

The present invention relates to a kind of preparation method's, particularly a kind of spinel structure of nanometer vectolite powder nanometer vectolite CoFe ₂O ₄The preparation method.

Background technology

The vectolite of spinel type is a kind of magneticsubstance of excellent property, has high saturation magnetization, plurality of advantages such as outstanding corrosion resistance nature and abrasion resistance properties.Its aspect magnetic recording, magnetics and magnetic fluid aspect are existing uses widely.In addition because its high resistivity and significant Kerr magnetooptical effect make it aspect absorbing material and the novel magneto-optic recording material great application potential arranged.Referring to: [1] " vectolite preparation and research thereof ", Zhang Chao, He'nan University's master thesis; [2] chemical method preparation technology and the absorbing property thereof of vectolite micro mist, Che Renchao, Li Yongqing etc., " aerospace material technology ",, the 6th phase in 1999; [3] Synthesis and characterization of size-controlled cobalt-ferrite-based ionic ferrofluids, Journal of Magnetism and Magnetic Materials, 225 (2001) 37-40.

At present, the preparation method of cobalt ferrite powder mainly contains sol-gel method, microemulsion method, solid reaction process and coprecipitation method etc., human sol-gel methodes such as Lee J G synthesize the nanometer vectolite, prepared vectolite nanoparticle mean sizes is about 30nm after 500 ℃ of calcinings of this method, referring to: Lee J G, Kim C S, Lee H M, et a1. Magnetic properties of CoFe2O4 powers and thin films by a sol-gel method [J]. J Magn Mater, 1998,177 (2): 900-902..T. human hydrothermal method such as Pannaparayil has prepared vectolite between 135 ~ 175 ℃, particle size is at 100 ~ 300nm, referring to: T. Pannaparayil and S. Komarneni, SYNTHESIS AND CHARACTERIZATION OF ULTRAFINE COBALT FERRITES, IEEE TRANSACTIONS ON MAGNETICS, VOL. 25, and NO. 5, SEPTEMBER 1989,4233-4235.N. human microemulsion method such as Moumen has prepared the vectolite particle of size at 2 ~ 5nm, referring to: N. Moumen and M. P. Pileni, New Syntheses of Cobalt Ferrite Particles in the Range 25 nm:Comparison of the Magnetic Properties of the Nanosized Particles in Dispersed Fluid or in Powder Form, Chem. Mater., 1996,8 (5), pp 1128 – 1134.Solid reaction process and sol-gel method all need the calcination process of comparatively high temps in the preceding method, referring to Chinese patent application 200410018797.8(publication number: CN101168452A) and Chinese patent application 201010045635.5(publication number: CN 101786668 A); The temperature of reaction of hydrothermal method is higher; Granule-morphology and the size of microemulsion method preparation are better, but complex process, productive rate are low, and residual organic matter is arranged.Coprecipitation method is the simple relatively method of a kind of technology, but general coprecipitation method also need just can be converted into spinel structure vectolite [3 under the temperature condition at boiling water or more than 60 ℃, 9] referring to Synthesis and characterization of size-controlled cobalt-ferrite-based ionic ferrofluids, Journal of Magnetism and Magnetic Materials, 225 (2001) 37-40 and Chinese patent application 200510018262.1(publication number: CN1657490A).Yeong Il Kim etc. directly prepare vectolite with NaOH precipitation molysite and cobalt salt solution, and by the controlling reaction temperature particle size, but be amorphous particle rather than ferrospinel what obtain below 60 ℃, referring to: Yeong Il Kim, Don Kim, Choong Su Lee, Synthesis and characterization of CoFe2O4 magnetic nanoparticles prepared by temperature-controlled coprecipitation method, PhysicaB337 (2003) 42 – 51.People such as M.Rajendran have provided a kind of method for preparing vectolite with NaOH and H2O2 mixing solutions co-precipitation molysite and cobalt salt solution, but the crystallization in the time of 20 ℃ of this method is relatively poor, referring to M.Rajendran, R.C.Pullar, A.K.Bhattacharya, D.Das S.N.Chintalapudi, C.K.Majumdar, Magnetic properties of nanocrystalline CoFe2O4 powders prepared at room temperature:variation with crystallitesize, Journal of Magnetism and Magnetic Materials, 232 (2001), 71 – 83.

Summary of the invention

The invention provides a kind of prior art deficiency that overcomes, can under lower temperature, prepare the method for cobalt ferrite powder with coprecipitation method.

Preparation spinel structure nanometer vectolite CoFe of the present invention ₂O ₄Method be:

1) is hybridly prepared into water solution A after taking by weighing iron trichloride and cobalt dichloride in proportion;

2) preparation NaOH or KOH alkaline solution, the back that stirs is to wherein dripping N ₂H ₄.H ₂O is to obtain solution B;

3) 20 ~ 40 ℃ of following water solution A of obtaining of quick whipping steps 1, and with step 2) the mixing solutions B for preparing slowly is added drop-wise to and reacts in the water solution A, obtains black precipitate;

4) the chocolate precipitation that step 3) reaction is produced with distilled water fully wash to the pH value be 7, use washing with alcohol again, drying treatment obtains the vectolite CoFe of spinel structure then ₂O ₄Powder.

Among the embodiment that the present invention provides, preparation spinel structure nanometer vectolite CoFe ₂O ₄The iron trichloride of Shi Suoyong is FeCl ₃.6H ₂O, used cobalt dichloride are CoCl ₂.6H ₂O, FeCl during preparation A solution ₃.6H ₂O and CoCl ₂.6H ₂The mol ratio of O is 2: 1, and prepared NaOH or KOH alkaline concentration are 1.5 ~ 2.5 mol/L, and the concentration of hydrazine hydrate is 4 ~ 7mol/L in the solution B of preparation.

Concentration of metal ions is 0.01M ~ 0.05M in the solution A in the embodiment of the invention.

Method of the present invention can be prepared vectolite CoFe at (between 20 ℃ to 40 ℃) under the lower temperature ₂O ₄Nanometer powder, and the resulting granules crystallization is better, and transmission electron microscope (TEM) photo shows that particle mean size is 3 ~ 9nm, and the grain-size of calculating with the X-ray diffraction spectrum meets, and is single crystal particle.Vibrating sample magnetometer (VSM) test shows particle at room temperature is superparamagnetism, and the specific magnetising moment is 11 ~ 40 emu/g under 1.2 T foreign fields.

Description of drawings

Fig. 1 is the X-ray diffraction spectrum of embodiment 1 product and embodiment 2 products.

Fig. 2 is TEM photo and the selected area electron diffraction figure (SAED) of embodiment 1 product.

Fig. 3 is TEM photo and the selected area electron diffraction figure (SAED) of embodiment 2 products.

Fig. 4 is the magnetic hysteresis loop that embodiment 1 product is measured with vibrating sample magnetometer (VSM).

Fig. 5 is the magnetic hysteresis loop that embodiment 2 products are measured with vibrating sample magnetometer (VSM).

Embodiment

The invention provides following specific embodiment.

Embodiment 1.

1) take by weighing 0.1784g(0.00066mol with mol ratio 2:1) FeCl ₃.6H ₂O and 0.07815g(0.00033mol) CoCl ₂.6H ₂O is dissolved in the 50ml distilled water, abundant stirring and dissolving, and concentration of metal ions is 0.02M.

2) taking by weighing 1.6g(0.04mol) NaOH is dissolved in the 20ml distilled water, and NaOH concentration is 2M.Stir the back to wherein dripping N ₂H ₄.H ₂The O(85% hydrazine hydrate) 10ml, N ₂H ₄.H ₂O concentration is 5.6mol/L.

3) exist Room temperatureFollowing (20 ^oC) stirring fast under the condition, with step 2) alkali that disposes and the mixing solutions of hydrazine hydrate slowly be added drop-wise in the solution of Fe, Co salt, reacted 2 hours.

4) black precipitate that the step 3) reaction is produced is fully washed to pH value about 7 with distilled water, uses washing with alcohol again 2 ~ 3 times, and seasoning or vacuum-drying then namely obtains the CoFe2O4 particle.

The X-ray diffraction of this routine gained sample spectrum shows the spinel nano crystal structure that crystal grain is in the accompanying drawing 1, and the grain-size of being calculated by diffraction peak is about 3 nm, and shows that particle size is consistent in the TEM photo of Fig. 2, is single crystal particle.Among Fig. 1 among X-ray diffraction spectrum and Fig. 2 SAED scheme all to show the particle well-crystallized.Fig. 4 routine sample for this reason at room temperature uses the measured magnetic hysteresis loop of VSM, is superparamagnetism under the show sample ability room temperature as a result, and the specific magnetising moment under 1.2 T foreign fields is 17 emu/g.

Embodiment 2.

3) exist 40 ^o CStirring fast under the water bath condition, with step 2) alkali that disposes and the mixing solutions of hydrazine hydrate slowly be added drop-wise in the solution of Fe, Co salt, reacted 2 hours.

4) black precipitate that the step 3) reaction is produced is fully washed to pH value about 7 with distilled water, uses washing with alcohol again 2 ~ 3 times, and seasoning or vacuum-drying then namely obtains the CoFe2O4 particle.Average particle size particle size is 9nm, is superparamagnetism under the room temperature, and 1.2 T are specific magnetising moment 40emu/g after the match outward.

The X-ray diffraction of this routine gained sample spectrum shows the spinel nano crystal structure that crystal grain is in the accompanying drawing 1, and the particle size of being calculated by diffraction peak is about 9 nm, and shows that particle size is consistent in the TEM photo of Fig. 3, is single crystal particle.Among Fig. 1 among X-ray diffraction spectrum and Fig. 3 SAED figure all show the particle well-crystallized, TEM photo demonstration particles dispersed is good.Fig. 5 routine sample for this reason at room temperature uses the measured magnetic hysteresis loop of VSM, is superparamagnetism under the show sample ability room temperature as a result, and the specific magnetising moment under 1.2 T foreign fields is 40 emu/g.

Embodiment 3.

2) take by weighing 1.2g(0.03mol) NaOH is dissolved in the 20ml distilled water, and NaOH concentration is 1.5M.Stir the back to wherein dripping N ₂H ₄.H ₂The O(85% hydrazine hydrate) 14ml, N ₂H ₄.H ₂O concentration is 7mol/L.

3) exist 20 ^o CStirring fast under the water bath condition, with step 2) alkali that disposes and the mixing solutions of hydrazine hydrate slowly be added drop-wise in the solution of Fe, Co salt, reacted 3 hours.

4) black precipitate that the step 3) reaction is produced is fully washed to pH value about 7 with distilled water, uses washing with alcohol again 2 ~ 3 times, and seasoning or vacuum-drying then namely obtains the CoFe2O4 particle.Average particle size particle size is 3nm, is superparamagnetism under the room temperature, and 1.2 T are specific magnetising moment 11emu/g after the match outward.

Embodiment 4.

2) take by weighing 2g(0.05mol) NaOH is dissolved in the 20ml distilled water, and NaOH concentration is 2.5M.Stir the back to wherein dripping N ₂H ₄.H ₂The O(85% hydrazine hydrate) 6ml, N ₂H ₄.H ₂O concentration is 3.8mol/L.

4) black precipitate that the step 3) reaction is produced is fully washed to pH value about 7 with distilled water, uses washing with alcohol again 2 ~ 3 times, and seasoning or vacuum-drying then namely obtains the CoFe2O4 particle.Average particle size particle size is 5nm, is superparamagnetism under the room temperature, and 1.2 T are the specific magnetising moment 13 emu/g after the match outward.

Above-described embodiment shows that method provided by the invention can at room temperature be prepared the nanocrystalline vectolite of good crystallization spinel structure, and particle size is below 10 nanometers, and particles dispersed is good.This method technology is simple, and cost is lower, for preparation and the application of nanometer cobalt ferrite powder provides a kind of valuable selection.

Claims

1. one kind prepares spinel structure nanometer vectolite CoFe ₂O ₄Method, it is characterized in that:

2) prepared NaOH or KOH alkaline solution, the back that stirs is to wherein dripping N ₂H ₄.H ₂O is to obtain solution B;

2. preparation spinel structure nanometer vectolite CoFe according to claim 1 ₂O ₄Method, it is characterized in that: used iron trichloride is FeCl ₃.6H ₂O, used cobalt dichloride are CoCl ₂.6H ₂O, FeCl during preparation A solution ₃.6H ₂O and CoCl ₂.6H ₂The mol ratio of O is 2: 1, and prepared NaOH or KOH alkaline concentration are 1.5 ~ 2.5 mol/L, and the concentration of hydrazine hydrate is 4 ~ 7mol/L in the solution B of preparation.

3. concentration of metal ions is 0.01M ~ 0.05M in the right 2 described solution A.