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Method for preparing La2-xBaxCuO4 powder by sol-gel method

A gel method and powder technology, applied in chemical instruments and methods, copper compounds, inorganic chemistry, etc., can solve problems such as time-consuming and unclear explanations, and achieve controllable morphology, easy-to-control reaction process, and composition evenly distributed effect

Active Publication Date: 2014-04-16
启东市滨化供水有限公司
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Problems solved by technology

Since the discovery of the first high-temperature superconducting oxide La by Bednoldz and Müller 2-x Ba x CuO 4 (LBCO), LBCO has been widely and deeply studied, and later people gradually found that in La 2-x Ba x CuO 4 In the system, when x is close to 1 / 8, Tc is strongly suppressed, and its normal physical properties are also relative to La 2-x Sr x CuO 4 In terms of abnormal behavior, that is, "1 / 8 anomaly", in the LBCO system, when x is around 1 / 8, there is a structural phase transition at low temperature, that is, from low-temperature orthorhombic (LTO) to low-temperature tetragonal phase (LTT) transition (from high temperature to low temperature), in La 2-x Ba x CuO 4 In superconductors, when La is replaced by 0.125 (1 / 8), the problem that the superconducting transition temperature is suppressed has always been a research hotspot, but the physical mechanism has not been explained clearly so far, and it is necessary to continue to study
[0003] Currently, the reported preparation of La 2-x Ba x CuO 4 The method is mainly solid phase method [HU Baofu, WANG Yanwen.STUDY OF La 2-x Ba x CuO 4 SUPERCONDUCTOR BY PAT[J].CHINESE JOURNAL OF LOW TEMPERATURE PHYSICS, 2005, 27(5):555-558.], [ZHANG Heng, DONG Xinfa, LIN Weiming.Synthesis and Oxygen Permeability of La 2-x Ba x CuO 4 Ceramic Membranes[J].Chinese Rare earths, 2007,28(2):30-32.], but in order to obtain the target product with high purity by solid state reaction method, the reactant powder should be fine enough, and it needs to be roasted at high temperature for a long time And many times of intermediate grinding, this method is time-consuming, and there are more impurity phases in the product

Method used

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  • Method for preparing La2-xBaxCuO4 powder by sol-gel method

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] 1) Get 50ml distilled water and add in the beaker, press La: Ba: Cu=1.9: 0.1: 1 molar ratio will analyze pure lanthanum nitrate (La(NO 3 ) 3 ·6H 2 O), barium nitrate (Ba(NO 3 ) 2 ) and copper nitrate (Cu(NO 3 ) 3 ·3H 2 O) add magnetic force stirring in the beaker and be configured to the solution A that the lanthanum nitrate concentration is 0.2mol / L until dissolving completely;

[0016] 2) The mol ratio of citric acid and metal cation sum is 1.2: 1 with analytically pure citric acid (C 6 h 8 o 7 ·H 2 O) add in solution A, stir at room temperature to obtain solution B;

[0017] 3) Add ammonia water with a mass percentage of 4% to solution B dropwise, adjust the pH to 2.1, and obtain solution C;

[0018] 4) Put the solution C into a blast drying oven, and dry it at a constant temperature of 80°C to obtain a xerogel;

[0019] 5) Grind the dry gel into powder with a mortar, put it into a crucible, put it into a muffle furnace, raise the temperature from room te...

Embodiment 2

[0022] 1) Get 35ml distilled water and add in the beaker, press La: Ba: Cu=1.98: 0.02: 1 molar ratio will analyze pure lanthanum nitrate (La(NO 3 ) 3 ·6H 2 O), barium nitrate (Ba(NO 3 ) 2 ) and copper nitrate (Cu(NO 3 ) 3 ·3H 2 O) add magnetic force stirring in the beaker and be mixed with solution A that the lanthanum nitrate concentration is 0.1mol / L until dissolving completely;

[0023] 2) The mol ratio of citric acid and metal cation sum is 2: 1 with analytically pure citric acid (C 6 h 8 o 7 ·H 2 O) add in solution A, stir at room temperature to obtain solution B;

[0024] 3) Add ammonia water with a mass percentage of 3% to solution B dropwise, adjust the pH to 1.5, and obtain solution C;

[0025] 4) Put the solution C into a blast drying oven, and dry it at a constant temperature of 60°C to obtain a xerogel;

[0026] 5) Grind the dry gel into powder with a mortar, put it into a crucible, put it into a muffle furnace, raise the temperature from room temperatu...

Embodiment 3

[0028] 1) Get 70ml distilled water and add in the beaker, press La: Ba: Cu=1.8: 0.2: 1 molar ratio will analyze pure lanthanum nitrate (La(NO 3 ) 3 ·6H 2 O), barium nitrate (Ba(NO 3 ) 2 ) and copper nitrate (Cu(NO 3 ) 3 ·3H 2 O) add magnetic force stirring in the beaker and be configured to the solution A that the lanthanum nitrate concentration is 0.3mol / L until dissolving completely;

[0029] 2) The mol ratio of citric acid and metal cation sum is 0.5: 1 with analytically pure citric acid (C6 h 8 o 7 ·H 2 O) add in solution A, stir at room temperature to obtain solution B;

[0030] 3) adding 5% ammonia water dropwise to solution B to adjust the pH to 4 to obtain solution C;

[0031] 4) Put the solution C into a blast drying oven, and dry it at a constant temperature of 110°C to obtain a xerogel;

[0032] 5) Grind the dry gel into powder with a mortar, put it into a crucible, put it into a muffle furnace, raise the temperature from room temperature to 900 °C at a h...

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Abstract

The invention relates to a method for preparing La2-xBaxCuO4 powder by a sol-gel method. The method comprises the steps that lanthanum nitrate, barium nitrate and copper nitrate are added into distilled water to obtain solution A, and citric acid is added into the solution A to obtain solution B; ammonia water is added into the solution B, and the pH is regulated to 1.5 to 4 to obtain solution C; the solution C is placed in a blowing drying box for constant-temperature drying to obtain dried gel; and the dried gel is ground into powder by a mortar, the powder is added in a crucible and is placed in a muffle furnace for heating reaction, then, the powder is cooled to the room temperature, substances in the powder are ground into the powder, and the La2-xBaxCuO4 powder is obtained. The low-cost sol-gel method in an inorganic system is adopted for preparing the La2-xBaxCuO4 powder, and the method has the advantages that the distribution of different components in the gel is uniform, the molecular level or the atomic level is reached, the reaction process is easy to control, the powder with larger specific surface area can be obtained, in addition, the equipment requirement is low, and the operation is simple. The obtained powder is the powder with the advantages that the grain diameter distribution is narrower, the appearance is controllable, and the component distribution is uniform. The method is an excellent method for preparing micron (nanometer)-level La2-xBaxCuO4 powder.

Description

technical field [0001] The present invention relates to a kind of La 2-x Ba x CuO 4 The preparation method of powder, be specifically related to a kind of sol-gel method and prepare La 2-x Ba x CuO 4 powder method. Background technique [0002] La 2-x m x CuO 4 Oxygen-deficient perovskite structures such as (M=Ca, Sr, Ba) have been extensively studied. Since the discovery of the first high-temperature superconducting oxide La by Bednoldz and Müller 2-x Ba x CuO 4 (LBCO), LBCO has been widely and deeply studied, and later people gradually found that in La 2-x Ba x CuO 4 In the system, when x is close to 1 / 8, Tc is strongly suppressed, and its normal physical properties are also relative to La 2-x Sr x CuO 4 In terms of abnormal behavior, that is, "1 / 8 anomaly", in the LBCO system, when x is around 1 / 8, there is a structural phase transition at low temperature, that is, from low-temperature orthorhombic (LTO) to low-temperature tetragonal phase (LTT) transiti...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01G3/00
Inventor 黄剑锋李意峰李碧曹丽云吴建鹏
Owner 启东市滨化供水有限公司