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Method for preparing nano superfine rare-earth hexaboride powder

The technology of hexaboride and ultrafine powder is applied in the field of preparation of rare earth hexaboride nanometer ultrafine materials, which can solve the problems of high cost of reaction vessel, difficulty of hexaboride and high product cost, and achieves low pressure and low price. , the effect of good appearance

Inactive Publication Date: 2011-01-19
SHANDONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since the reaction temperature is 400-600°C, if the pressure in the system is very high, there will be higher requirements for the closed reaction vessel, which will make it difficult to scale up the preparation of hexaboride in the closed system.
The applicant used rare earth / alkaline earth metal oxides to react with boron sources such as boron oxide / boron powder / boric acid through iodine-assisted magnesium co-reduction, and synthesized a variety of hexaborides under mild conditions (170-500°C). See ZL200910014675 .0 "Method for synthesizing lanthanum hexaboride nanopowders at low temperature by solid phase reaction" and CN201010178836.2 "Method for synthesizing metal boride nanopowders by solid state reaction with iodine-assisted magnesium co-reduction", but there are still Therefore, due to safety factors during scale-up preparation and application, it is necessary to consider the requirements of the material and pressure resistance of the reaction vessel, resulting in a relatively high cost of the reaction vessel
In addition, the auxiliary agent used, such as: I 2 The cost is relatively high, resulting in high product cost, so it is necessary to further optimize the preparation conditions, reduce the preparation cost, so that it can be produced at a lower temperature (<650°C) and without pressure (or lower pressure, such as normal pressure) or close to atmospheric pressure) to achieve low-cost macro-scale preparation

Method used

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  • Method for preparing nano superfine rare-earth hexaboride powder
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  • Method for preparing nano superfine rare-earth hexaboride powder

Examples

Experimental program
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Effect test

Embodiment 1

[0044] Embodiment 1. synthetic LaB 6

[0045] The source of lanthanum is lanthanum chloride and lanthanum oxychloride, with LaCl 3 Based on the LaOCl mixture, the molar ratio is 5:1. After uniformly mixing 156g of lanthanum source, 250g of magnesium powder, and 223g of boron oxide, they are placed in a 500mL reactor. The opening was compacted, placed in a resistance crucible boiler, and reacted at 600 ° C for 10 hours; the reactor was naturally cooled to room temperature; the initial product and ice were mixed according to a mass ratio of 1:2, and then a small amount of hydrochloric acid (hydrochloric acid 0.3 times Mg molar amount in the raw material), after stirring for 10 minutes, add hydrochloric acid in several times to make the final concentration of hydrochloric acid in the system 3mol / L, and the temperature is ≤95°C; heat the solution containing the initial product after preliminary hydrochloric acid treatment and maintain it at 50-90 °C, after 1-5 hours of treatment...

Embodiment 2

[0047] Example 2. Synthesis of CeB 6

[0048] The source of cerium is cerium chloride and cerium oxide, with CeO 2 and CeCl 3 According to the molar ratio of 1:6, 0.80g of cerium source, 1.25g of magnesium powder, and 1.02g of boron oxide were uniformly mixed, put in a 25mL reactor, and kept at 600°C for 10 hours, because the amount of the initial product was relatively small , The heat generated by the use of hydrochloric acid and the initial product is relatively small compared to the system, which will not cause the system to boil, so it is only acid-washed with 3 mol of hot hydrochloric acid (40 ° C), filtered, washed with alcohol solvent, and vacuum-dried. Obtain cubic CeB with an average particle size of 50 nm or less 6 . Figure 4 For its XRD, due to the small particle size of the obtained product, the diffraction peaks are slightly shifted to high angles, but ten of the peaks can be indexed as CeB in the body-centered cubic system 6 According to Scherrer's formula...

Embodiment 3

[0049] Embodiment 3. synthetic LaB 6

[0050] Lanthanum source is lanthanum chloride, LaCl 3 2.474g, 2.076g of magnesium powder, and 1.715g of boron oxide were mixed, placed in a 20mL reactor, and kept at 650°C for 8 hours. Since the amount of the initial product is relatively small, the heat generated by using hydrochloric acid and the initial product is relatively small, thus the system temperature will not be caused to rise sharply. Therefore, after it is cooled down to room temperature, it is treated in hot dilute hydrochloric acid (45 ° C), filtered after pickling, washed with alcohol, and dried in vacuum to obtain a compound containing LaB 6 of powder. Image 6 It is the X-ray diffraction spectrum of the product obtained in Example 3. Depend on Image 6 It can be seen that the product contains LaB 6 The product, the weaker impurity peak is LaOCl.

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Abstract

The invention relates to a method for preparing nano superfine rare-earth hexaboride powder. In the presence of a reducing agent, a metal resource raw material and a boron source raw material react in a reactor at the temperature of between 500 and 650 DEG C to form a product. In the method, the nano superfine rare-earth hexaboride powder is prepared by solid phase reaction under the conditions of lower temperature and no obvious pressure. Compared with the conventional boron thermal reduction and carbon thermal reduction technology, the method of the invention has the advantages of lower reaction temperature, no need of pressure, low raw material cost and probability of realizing mass production.

Description

technical field [0001] The invention belongs to the technical field of preparation of rare earth hexaboride nano-ultrafine materials, in particular to a method for synthesizing hexaboride ultra-fine nano-powder materials at relatively low temperature and low pressure by solid phase reaction. Background technique [0002] Rare earth metal hexaboron compound (RB 6 ) has the structure of CsCl, the difference is that B 6 Octahedral clusters occupy the Cl positions in the CsCl structure. The strong covalent bonds between B atoms in the structure make it form a tight space network, so RB 6 Compounds generally have the characteristics of low volatility, low work function, high melting point, high strength and high stability, which make them important field emission materials and are widely used in cutting-edge instruments such as electron microscope filaments. due to B 6 The octahedral space network structure needs two electrons to make it stable, and the metal elements with di...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B35/04
Inventor 钱逸泰王连成徐立强马小健
Owner SHANDONG UNIV
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