CN100522872C

CN100522872C - Method for preparing nano spinel ferrite with equal grain size

Info

Publication number: CN100522872C
Application number: CNB200710121823XA
Authority: CN
Inventors: 李峰; 顾智军; 项顼
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2007-09-14
Filing date: 2007-09-14
Publication date: 2009-08-05
Anticipated expiration: 2027-09-14
Also published as: CN101157549A

Abstract

The invention relates to a preparation method of particle size homogeneous nanometer spinel ferrite, which belongs to the art of the metal oxides preparation. Metallic ion is first deoxidized into highly scattered nanometer metallics in a colloid mill, and then the blended solution containing the nanometer metallics is transferred into a Teflon gallbladder for water hot crystallization under high-pressured reaction so as to form the spinel ferrite particle with a diameter of 5 to 200 nanometers. The invention has the advantages that the high-speed shearing action of the colloid mill ensures that the deoxidized metallics are highly dispersed, thereby enabling the particle size homogeneous nanometer spinel ferrite. The reaction is carried in the solution, and the diameter of the nanometer particle can be controlled through adjusting the reactant density, the reaction temperature and the reaction time; since no need for high-temperature roasting process in the reaction, the operation becomes quite easy. Moreover, the invention has low cost and low energy consumption, thereby being favorable for industrialized application.

Description

A kind of preparation method of nano spinel ferrite of uniform particle diameter

Technical field

The invention belongs to and belong to the preparation of metal oxides technical field, particularly a kind of preparation method of nano spinel ferrite of uniform particle diameter is at the controlled preparation particle diameter of cold condition.

Background technology

The composite oxides that ferrite is made up of iron and other one or more metals are widely used in every field such as communication broadcasting, radar navigation, space travel, medical biotechnology.In recent years, along with the continuous development of Materials science, the R and D of nano material also are used to prepare Ferrite Material, make the performance of Ferrite Material be greatly improved and improve.Because the distinctive specific surface effect of nano material, small-size effect, interfacial effect and macroscopic quantum effect, show physical propertiess such as the light different, electricity, heat, magnetic with conventional material, make material have many new special functions, thereby cause people's very big concern.

The ceramic post sintering method is mainly adopted in present ferritic preparation, and promptly product is by behind the mixed grinding obtaining metal oxide, carbonate or nitrate by a certain percentage in high-temperature roasting.Because the reaction mixture reaction not exclusively need be with sample regrinding and roasting usually.Because active relatively poor, the mixture homogeneity and the fineness of these firing precursor raw materials are not high, therefore exist and react the defective that is difficult for complete, whole homogeneity difference in the ferritic process of preparation, finally have influence on ferritic performance.When adopting this method, because the structure of reactant and resultant exists than big-difference, relate to the reorganization of chemical bond in the solid state reaction, need between the atom to move the formation crystal phase structure that to interact through long-range, so generally need higher temperature (more than 900 ℃), the time (more than the 12h) and the repeatedly roasting of length, this is disadvantageous on industrial production.Simultaneously, therefore in the process of material preparation, there is the defective of reacting incomplete, whole homogeneity difference, finally has influence on the performance and the application of material because active relatively poor, the mixture homogeneity of these firing precursor raw materials and fineness are not high.Therefore, explore new synthetic method and seem particularly important.At this situation, people have carried out preparation technology's improvement energetically, as document D.Arcos, R.Valeuzuela, M.Vazquez, et al.Chemical homogeneity of nanocrystalline Zn-Mn spinel ferrites obtained by high-energyball milling.J Solid State Chem, 1998,141:10-16. mills by high energy and has prepared the nano spinel ferrite that cation dispersion is different from traditional method; Document T.Valdes-solis, G.Marban, A.B.Fuertes.Preparation of nanosized perovskite and spinels through a silica xerogel template Route.Chem.Mater, 2005,17 (8): it is template that 1919-1922 adopts the silicon gel, has prepared the nanometer ferrite that has than bigger serface.But because above these synthetic methods adopt mixture roasting system, the mixture homogeneity of firing precursor and fineness can't largely be adjusted from microcosmic, cause also existing the inhomogeneous of The Nomenclature Composition and Structure of Complexes in the product, and then have influence on the physical and chemical performance of product.Simultaneously, be difficult in the high-temperature calcination process size of particles of product is control effectively, energy consumption is big, is unfavorable for industrial applications.In addition, document C.Liu, B.Zou, A.J.Rondinone, and Z.J.Zhang, Reverse Micelle Synthesis and Characterization ofSuperparamagnetic MnFe2O4 Spinel Ferrite Nanocrystallites, J.Phys.Chem.B, Vol.104, No.6,2000 also the report utilize the reverse microemulsion legal system to be equipped with the nanostructured manganese ferrite.Owing to when synthetic, need consume a large amount of organic surface active agents, have that operation easier is big, preparation cost is high, the environmental pollution important disadvantages,

Summary of the invention

The object of the present invention is to provide a kind of preparation method of nano spinel ferrite of uniform particle diameter, the solution problem that operation easier is big, preparation cost is high, environmental pollution is serious of knowing clearly has realized the nano spinel ferrite of controlled preparation uniform particle diameter under the cold condition.

The present invention utilizes the high dispersive effect of colloidal mill and the reductibility of sodium borohydride, obtains the nano metal particles colloidal sol of high dispersing, generates even-grained ferrospinel nanoparticle afterwards in the process of hydrothermal crystallizing.By the control preparation condition, can realize regulation and control to the size of ferrospinel nanoparticle.A kind of novel method for preparing the ferrospinel nano material is provided.

Ferrospinel is a class and natural magnesium aluminate (MgAl ₂O ₄) have a ferrite of analog structure.The Mg of natural magnesium aluminate and Al ion can be by other divalence (Ni ²⁺, Co ²⁺, Fe ²⁺, Mn ²⁺Deng) or trivalent (Fe ³⁺, Cr ³⁺Deng) ion substitution.MgAl ₂O ₄Spinel belongs to isometric system, and spacer is Dh7-F3dm, comprises 56 ions in each unit cell, and wherein the divalent metal ion is 8,16 of 3 valence metal ions, 32 oxonium ions.In the structure cell of spinel, 32 Sauerstoffatoms constitute the face-centered cubic closest packing, comprising its 64 tetrahedron spaces and 32 octahedral interstices.Metal ion occupies 8 tetrahedron spaces (A position) and 16 octahedral interstices (B position) wherein respectively.The subcell that occupies the A position is arranged by tetrahedron, and the subcell that occupies the B position is arranged by the complementary tetrahedron.If the A position is all occupied by divalent ion, be called positive spinel, if the A position is all occupied by trivalent ion, be called inverse spinel.

The present invention utilizes the polymolecularity of colloidal mill simultaneously by earlier metal ion being reduced to nano metal particles in solution, makes the nano metal particles that is reduced disperse to form colloid at the solution camber.By the hydrothermal crystallizing oxidising process, form the uniform nanometer ferrite metal oxide of particle diameter afterwards.

Concrete steps are as follows:

A. preparation contains the mixing solutions of the soluble salt of metal ions M and M2.The volumetric molar concentration of each metal ion species is respectively M1:0.1～0.5M, M2:0.2～1.0M; Take by weighing a certain amount of sodium borohydride (NaBH ₄) and tensio-active agent, be mixed with mixing solutions.Wherein, the concentration of sodium borohydride is 0.4～2.0M, and surfactant concentrations is 1.5～6.0g/L;

B. the mixing solutions of isopyknic mixing salt solution and sodium borohydride and tensio-active agent is together poured in the colloidal mill of high speed rotating (3000-6000 rev/min), stirred 5-10 minute, metal ion is fully reduced, obtain containing the mixing solutions of nano metal particles;

C. the mixing solutions that obtains is changed in the autoclave of polytetrafluoroethylliner liner,, naturally cool to room temperature afterwards in 120-240 ℃ of hydrothermal crystallizing 3-48 hour.Filter, wash, obtaining median size is the ferrospinel particle of 5 to 200 nanometers.

M1 in the steps A is Co ²⁺, Mn ²⁺, Cu ²⁺, Ni ²⁺In 1～4 kind; M2 is Fe ²⁺Or Fe ³⁺In a kind of; Acid ion in the mixed salt solution is Cl ^-, NO ₃ ^-Or SO ₄ ^2-In any 1～3 kind; Tensio-active agent is a kind of in polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA) or the oleic acid (OA).

The present invention has following unusual effect:

1, Zhi Bei nano spinel ferrite has advantages such as particle diameter is little, even particle size distribution, has overcome raw material that traditional solid state reaction exists and has mixed inhomogeneous, active low, product and have the shortcomings such as ununiformity on the The Nomenclature Composition and Structure of Complexes;

2, carry out owing to being reflected in the solution, can be by adjusting conditions such as concentration of reactants, temperature of reaction, reaction times, the size of control material realizes the controlled preparation to the ferrospinel material;

3, owing to do not need high-temperature calcination process, reduce energy consumption, saved cost, be fit to suitability for industrialized production.

Embodiment

Embodiment 1:

By the accurate weighing Co of stoichiometric ratio (NO ₃) ₃6H ₂O, Fe (NO ₃) ₃9H ₂O is mixed with mixing salt solution with deionized water, and GOLD FROM PLATING SOLUTION belongs to ionic concentration and is respectively: [Co ²⁺]=0.2M, [Fe ³⁺]=0.4M inserts this mixing solutions in the beaker.Other prepares NaBH ₄And the mixing solutions of polyvinylpyrrolidone (PVP), wherein [NaBH ₄]=1.5M, [PVP]=1.8g/L.With isopyknic mixing salt solution and NaBH ₄Together pour (6000 rev/mins) in the atwirl colloidal mill, vigorous stirring 5 minutes into the mixing solutions of PVP.Afterwards, the nano-metal particle that reduction obtains is transferred in the autoclave of polytetrafluoroethylliner liner, in 120 ℃ of hydrothermal crystallizings 12 hours.After naturally cooling to room temperature, will obtain precipitate with deionized water and be washed till neutrality.In 40 ℃ of dryings 12 hours, obtain the CoFe that median size is 18nm ₂O ₄The spinel nano particle.

Embodiment 2:

By the accurate weighing Ni of stoichiometric ratio (NO ₃) ₃6H ₂O, Fe (NO ₃) ₃9H ₂O is mixed with mixing salt solution with deionized water, and GOLD FROM PLATING SOLUTION belongs to ionic concentration and is respectively: [Ni ²⁺]=0.25M, [Fe ³⁺]=0.5M inserts this mixing solutions in the beaker.Other prepares NaBH ₄And the mixing solutions of polyvinyl alcohol (PVA), wherein [NaBH ₄]=1.0M, [PVA]=3.2g/L.With isopyknic mixing salt solution and NaBH ₄Together pour (4500 rev/mins) in the atwirl colloidal mill, vigorous stirring 5 minutes into the mixing solutions of PVA.Afterwards, the nano-metal particle that reduction obtains is transferred in the autoclave of polytetrafluoroethylliner liner, in 200 ℃ of hydrothermal crystallizings 24 hours.After naturally cooling to room temperature, will obtain precipitate with deionized water and be washed till neutrality.In 40 ℃ of dryings 12 hours, obtain the NiFe that median size is 52nm ₂O ₄The spinel nano particle.

Embodiment 3:

By the accurate weighing Co of stoichiometric ratio (NO ₃) ₃6H ₂O, Fe (NO ₃) ₃9H ₂O, Cu (NO ₃) ₂3H ₂O is mixed with mixing salt solution with deionized water, and GOLD FROM PLATING SOLUTION belongs to ionic concentration and is respectively: [Co ²⁺]=0.4M, [Fe ³⁺]=1.0M, [Cu ²⁺]=0.1M inserts this mixing solutions in the beaker.Other prepares NaBH ₄And the mixing solutions of polyvinylpyrrolidone (PVP), wherein [NaBH ₄]=1.2M, [PVP]=4.0g/L.With isopyknic mixing salt solution and NaBH ₄Together pour (3000 rev/mins) in the atwirl colloidal mill, vigorous stirring 7 minutes into the mixing solutions of PVP.Afterwards, the nano-metal particle that reduction obtains is transferred in the autoclave of polytetrafluoroethylliner liner, in 150 ℃ of hydrothermal crystallizings 6 hours.After naturally cooling to room temperature, will obtain precipitate with deionized water and be washed till neutrality.In 40 ℃ of dryings 12 hours, obtain the Co that particle diameter is 27nm _0.8Cu _0.2Fe ₂O ₄The spinel nano sheet.

Embodiment 4:

By the accurate weighing Ni of stoichiometric ratio (NO ₃) ₃6H ₂O, FeCl ₂4H ₂O, Cu (NO ₃) ₃3H ₂O is mixed with mixing salt solution with deionized water, and GOLD FROM PLATING SOLUTION belongs to ionic concentration and is respectively: [Ni ²⁺]=0.3M, [Cu ²⁺]=0.2M, [Fe ²⁺]=1.0M inserts this mixing solutions in the beaker.Other prepares NaBH ₄And the mixing solutions of oleic acid (OA), wherein [NaBH ₄]=1.0M, [OA]=1.5g/L.With isopyknic mixing salt solution and NaBH ₄Together pour (3500 rev/mins) in the atwirl colloidal mill, vigorous stirring 10 minutes into the mixing solutions of OA.Afterwards, the nano-metal particle that reduction obtains is transferred in the autoclave of polytetrafluoroethylliner liner, in 240 ℃ of hydrothermal crystallizings 48 hours.After naturally cooling to room temperature, will obtain precipitate with deionized water and be washed till neutrality.In 40 ℃ of dryings 12 hours, obtain the Ni that median size is 158nm _0.6Cu _0.4Fe _.2O ₄The spinel nano particle.

Embodiment 5:

By the accurate weighing MnCl of stoichiometric ratio ₂4H ₂O, Co (NO ₃) ₃6H ₂O, FeCl ₃6H ₂O is mixed with mixing salt solution with deionized water, and GOLD FROM PLATING SOLUTION belongs to ionic concentration and is respectively: [Mn ²⁺]=0.3M, [Co ²⁺]=0.2M, [Fe ³⁺]=1.0M inserts this mixing solutions in the beaker.Other prepares NaBH ₄And the mixing solutions of polyvinylpyrrolidone (PVP), wherein [NaBH ₄]=1.7M, [PVP]=3g/L.With isopyknic mixing salt solution and NaBH ₄Together pour (4000 rev/mins) in the atwirl colloidal mill, vigorous stirring 8 minutes into the mixing solutions of PVP.Afterwards, the nano-metal particle that reduction obtains is transferred in the autoclave of polytetrafluoroethylliner liner, in 180 ℃ of hydrothermal crystallizings 16 hours.After naturally cooling to room temperature, will obtain precipitate with deionized water and be washed till neutrality.In 40 ℃ of dryings 12 hours, obtain the Co that median size is 31nm _0.4Mn _0.6Fe ₂O ₄The spinel nano particle.

Claims

1. the preparation method of the nano spinel ferrite of a uniform particle diameter is characterized in that, processing step is:

A. contain the mixing solutions of the soluble salt of metal ions M 1 and M2 according to the mol ratio preparation of M1:M2=1:2, wherein the volumetric molar concentration of each metal ion species is respectively M1:0.1～0.5M, M2:0.2～1.0M; The mixing solutions of preparation sodium borohydride and tensio-active agent, wherein the concentration of sodium borohydride is 0.4～2.0M, surfactant concentrations is 1.5～6.0g/L; M1 is Co ²⁺, Mn ²⁺, Cu ²⁺, Ni ²⁺In 1～4 kind; M2 is Fe ²⁺Or Fe ³⁺In a kind of; Acid ion in the mixed salt solution is Cl ^-, NO ₃ ^-Or SO ₄ ^2-In any 1～3 kind; Tensio-active agent is a kind of in polyvinylpyrrolidone, polyvinyl alcohol or the oleic acid;

B. the mixing solutions of isopyknic mixing salt solution and sodium borohydride and tensio-active agent is together poured in 3000-6000 rev/min the colloidal mill, stirred 5-10 minute, metal ion is reduced, obtain containing the mixing solutions of nano metal particles;

C. the mixing solutions of B step is transferred in the autoclave of polytetrafluoroethylliner liner,, naturally cooled to room temperature afterwards in 120-240 ℃ of hydrothermal crystallizing 3-48 hour; After filtration, the washing, obtaining particle diameter is the ferrospinel particle of 5～200 nanometers.