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Preparation method of perovskite composite oxide La1-xCaxFeO3 superfines

A composite oxide and ultra-fine powder technology, applied in the direction of iron oxide/iron hydroxide, etc., can solve the problems of high crystallization temperature, difficult drying of wet gel, large product size, etc., to achieve the effect of low melting point and avoid hydrolysis segregation

Inactive Publication Date: 2012-08-01
SHANXI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Commonly used sol-gel processes include alcohol salt hydrolysis method and complex sol-gel method. The existing complex sol-gel method uses citric acid as complexing agent, which has high crystallization temperature, large product size, and wet gel difficult to dry

Method used

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  • Preparation method of perovskite composite oxide La1-xCaxFeO3 superfines
  • Preparation method of perovskite composite oxide La1-xCaxFeO3 superfines

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Embodiment 1: weigh 4.33g lanthanum nitrate, 4.04g ferric nitrate and 22.75g stearic acid. First melt the stearic acid, then add solid lanthanum nitrate and iron nitrate to the molten stearic acid, and stir at 75°C for 5 hours until a sol is formed. Benzene was added to the sol for azeotropic distillation and natural drying to obtain a gel. Then the gel was placed in a muffle furnace and pre-calcined at 500°C for 2 hours to obtain a powdery precursor, which was taken out and fully ground. Finally, put it in a muffle furnace and calcinate it at 700°C for 5 hours to get LaFeO 3 powder. The sample is LaFeO with a perovskite structure 3 , the degree of crystallization is good, and no impurity phase appears (see figure 1 a). LaFeO 3 The particle size of the powder reaches about 150nm (see figure 2 a).

Embodiment 2

[0016] Embodiment 2: weigh 4.11g lanthanum nitrate, 0.12g calcium nitrate, 4.04g ferric nitrate and 22.75g stearic acid. First melt stearic acid, add lanthanum nitrate, calcium nitrate and iron nitrate solids into the molten stearic acid, stir at 70°C for 7 hours until a sol is formed. Benzene was added to the sol for azeotropic distillation and natural drying to obtain a gel. Then the gel was placed in a muffle furnace and pre-calcined at 400°C for 2 hours to obtain a powdery precursor, which was taken out and fully ground. Finally, put it in a muffle furnace and calcinate at 800°C for 5 hours to obtain La 0.95 Ca 0.05 FeO 3 powder. The crystal phase contained in the sample is mainly perovskite structure, which does not change the LaFeO 3 The preferred orientation of the crystal planes of the crystal increases the intensity of the diffraction peaks of each crystal plane, reduces the distance between each crystal plane and the average linear size of crystal grains. (See ...

Embodiment 3

[0017] Embodiment 3: weigh 3.90g lanthanum nitrate, 0.24g calcium nitrate, 4.04g ferric nitrate and 25.60g stearic acid. First melt stearic acid, add lanthanum nitrate, calcium nitrate and iron nitrate solids to the molten stearic acid, stir at 72°C for 6 hours until a sol is formed. Benzene was added to the sol for azeotropic distillation and natural drying to obtain a gel. Then the gel was placed in a muffle furnace and pre-calcined at 450°C for 2 hours to obtain a powdery precursor, which was taken out and fully ground. Finally, put it in a muffle furnace and calcinate at 750°C for 5 hours to obtain La 0.9 Ca 0.1 FeO 3 powder. The sample has a perovskite structure, the degree of crystallization is good, and no impurity phase appears (see figure 1 c). La 0.9 Ca 0.1 FeO 3 The particle size of the powder reaches about 200nm (see figure 2 c).

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Abstract

The invention provides a preparation method of perovskite composite oxide La1-xCaxFeO3 superfines, comprising the following steps: heating and melting stearic acid; adding lanthanum nitrate, calcium nitrate and ferric nitrate; at the temperature of 70-75 DEG C, stirring for more than 5 hours until sol is formed; adding benzene; carrying out azeotropic distillation, naturally drying and obtaining gel; performing precalcination for 2 hours at the temperature of 400-600 DEG C; fully grinding; and finally calcining for 5 hours at the temperature of 600-800 DEG C to obtain the product. The invention adopts stearic acid as complexing agent, and overcomes the problems of high crystallization temperature, large product size, difficult drying of wet gel and the like of the traditional sol gel process; a precursor and benzene carry out azeotropic distillation to remove moisture in wet gel as much as possible, thus avoiding powder agglomeration during calcination. The sample prepared by the invention has perovskite structure, so that crystallization degree is favourable, no impurity phase appears, dopant atom CA enters the node position of LaFeO3, and the grain diameter of the product is within 100-200nm.

Description

technical field [0001] The present invention relates to a perovskite type composite oxide, in particular to a perovskite type composite oxide La 1-x Ca x FeO 3 Preparation method of ultrafine powder. Background technique [0002] Perovskite composites have special optical, electrical, thermal and magnetic properties, and can be used as superconducting materials, ferromagnets, ferroelectrics, piezoelectric ceramics, thermistors, oxygen electrodes, etc. Yue Guang occupies a very important position in material science and is a new type of functional material with a wide range of uses. Perovskite-type composite oxides have aroused widespread interest because of their special stable crystal structure, properties and broad application prospects. Such as La 1-x A x MnO 3 Due to its special electromagnetic properties, it has been widely used in solid fuel cells, solid electrolytes, sensors and catalysts. And La x Ba 1-x CoO 3 Conductive ceramics can be used in many aspect...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01G49/02
Inventor 赵晓红杨丽萍董川
Owner SHANXI UNIV
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