Method of one-step synthesis of hexagonal barium ferrite nanometer crystal by microwave-assistant sol-gel spontaneous combustion

A microwave-assisted, barium ferrite technology, applied in chemical instruments and methods, iron compounds, inorganic chemistry, etc., can solve the problems of difficult control of grain size, agglomeration and adhesion of grains, and avoid difficult control and dispersion of grain size. Good performance and uniform particle size

Inactive Publication Date: 2009-10-21
NANJING UNIV OF TECH
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Problems solved by technology

[0005] The present invention aims to solve the need to carry out secondary heat treatment on the combustion product at a higher temperature when the existing general sol-gel self-combustion method is used to prepare the hexagonal barium ferrite powde

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  • Method of one-step synthesis of hexagonal barium ferrite nanometer crystal by microwave-assistant sol-gel spontaneous combustion
  • Method of one-step synthesis of hexagonal barium ferrite nanometer crystal by microwave-assistant sol-gel spontaneous combustion
  • Method of one-step synthesis of hexagonal barium ferrite nanometer crystal by microwave-assistant sol-gel spontaneous combustion

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Embodiment 1

[0030] 1) Using analytically pure barium nitrate and ferric nitrate as raw materials, press BaFe 12 o 19 The stoichiometric relationship of the middle components means that an appropriate amount of barium nitrate and ferric nitrate are dissolved in an appropriate amount of deionized water to obtain barium nitrate and ferric nitrate solutions, and their concentrations are respectively: [Ba 2+ ]=0.02M, [Fe 3+ ]=0.24M;

[0031] 2) Add complexing agents ethylenediaminetetraacetic acid (EDTA), citric acid (CA) and ethylene glycol (EG) to the above solution, the amount of which is added according to (ME DTA+ m CA ) / M Ba+Fe =1.5, M EDTA / M CA = 1 / 6 and M EG / (M EDTA+ m CA )=1.2, then stirred until all dissolved. Further, ammonium nitrate was added according to the oxidation degree Q=0.8, and the pH value of the solution was adjusted to 7.0 with ammonia water, and the reaction was refluxed and stirred at 25°C for 2 hours to obtain a completely reacted uniform sol;

[0032] ...

Embodiment 2

[0035] 1) Using analytically pure barium nitrate and ferric nitrate as raw materials, press BaFe 12 o 19 The stoichiometric relationship of the middle components is called an appropriate amount of barium nitrate and ferric nitrate and is dissolved in an appropriate amount of deionized water respectively to obtain barium nitrate and ferric nitrate solutions, and their concentrations are respectively: [Ba 2+ ]=0.01M, [Fe 3+ ]=0.12M;

[0036] 2) Add ethylenediaminetetraacetic acid (EDTA) and urea (Ur) to the solution of barium nitrate and ferric nitrate in the solution, the addition amount is according to M EDTA / M Ba+Fe =1.0, M Ur / M Ba+Fe =1.0 equimolar ratio. Add ammonium nitrate to the solution according to the degree of oxidation Q=1.0, and adjust the pH value of the solution to 6.5 with concentrated ammonia water, then stir and react at room temperature (20° C.) for 2 hours to ensure sufficient reaction, and obtain a completely reacted uniform sol;

[0037] 3) Slowly...

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Abstract

The invention provides a preparation method of one-step synthesis of hexagonal barium ferrite (BaFe12O19) nanometer crystal by microwave-assistant sol-gel spontaneous combustion process. The technical scheme comprises the following steps: 1) nitrate Ba(NO3)2 and Fe(NO3)3 are taken as the raw materials; water solution with certain concentration is prepared according to barium ferrite chemometry; citric acid, ethylene diamine tetraacetic acid, urea, glucose and glycol and other organic reagents or compound thereof are taken as complexing agent of metal ion and hydrocarbon fuel required by sol-gel spontaneous combustion; ammonium nitrate and ammonium hydroxide are in addition added to adjust content of systematic oxidizer and PH value; even sol is formed by complexation. 2) xerogel which with desirable residual moisture content is prepared by using liquid nitrogen quick-freezing sol and vacuum condensation drying process. 3) the xerogel is compressed to form a block which is put into a quartz reaction chamber with microwave absorptive character; the xerogel is induced for spontaneous combustion in a microwave field, single-phase barium ferrite nanometer crystal is synthesized in one step which is precise in components and even in granule size; the invention can be used to prepare quasi-single crystal texture millimeter wave gyromagnetic ferrite.

Description

Technical field: [0001] The invention relates to a microwave-assisted sol-gel self-combustion method for one-step synthesis of barium hexagonal barium ferrite nanocrystals, which belongs to the technical field of advanced functional material preparation. Background technique: [0002] M-type barium hexagonal ferrite (BaFe 12 o 19 , BaM) has gradually become one of the most commonly used oxide permanent magnets because of its low preparation cost and high magnetic product energy since it was first synthesized by J.L.Went in 1952. In recent years, people have begun to pay attention to the characteristics of high coercive field, saturation magnetization, magnetocrystalline anisotropy field and good chemical corrosion resistance of M-type barium hexagonal ferrite, and have been widely used as radar wave absorbing materials, high-performance vertical Research on the synthesis, preparation and application of recording materials and gyromagnetic materials for millimeter wave devi...

Claims

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Application Information

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IPC IPC(8): C01G49/00
Inventor 曾燕伟刘俊亮张伟
Owner NANJING UNIV OF TECH
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