CN104525940A - Bismuth micron particle and manufacturing method thereof - Google Patents

Abstract

The invention provides a bismuth micron particle. The particle is a bismuth elementary substance, the particle size of the particle is 1 micron to 3 microns, and the particle is spherical or polyhedral. The method for manufacturing the particle comprises the following steps that a bismuth source and template agents are added to glycol and stirred to be completely dissolved, then the pH value of a solution is adjusted to be larger than 10 while stirring is carried out, after solute is completely dissolved, the solution is transferred into a closed polytetrafluoroethylene lining high-pressure reaction still, a reaction is carried out for more than 10 h under the condition of 160 DEG C to 200 DEG C, a product is centrifuged or filtered after the reaction is finished, residual solute is removed through washing, and the bismuth micron particle can be obtained through drying and cooling. The positive colossal magnetoresistance of the bismuth micron particle is more than 700 percent at low temperature, the positive colossal magnetoresistance of the bismuth micron particle is more than 180 percent at indoor temperature, and the manufacturing method of the bismuth micron particle is simple.

Description

A kind of bismuth microparticle and preparation method thereof

technical field

The invention provides a bismuth micron particle, in particular to a method for preparing a high giant magnetic effect bismuth micron particle in an alkaline environment, and belongs to the technical fields of chemical engineering and functional micro-nano materials.

Background technique

The giant magnetoresistance effect refers to the phenomenon of huge changes in material resistance caused by an external magnetic field, which can be used in information technology fields such as magnetic recording, magnetic head readout, magnetic information storage, giant magnetoresistance sensors, and magnetoelectronics.

Bismuth is a semimetal with unique electrical properties due to its high anisotropic Fermi surface, low carrier concentration, and small carrier effective mass. Because bismuth has a large Fermi wavelength and a long carrier mean free path, a lot of research has focused on its quantum transport and size confinement effects. The extremely small carrier effective mass and mean free path make bismuth have a very good giant magnetoresistance effect. Bismuth elemental substances including thin films, bulks and nanomaterials with various shapes have been successfully synthesized and studied. The synthesis process includes chemical or physical vapor deposition, electrochemical deposition, solution reduction method and so on. Among them, the giant magnetic effect of bismuth elemental micron single crystal thin film is the most excellent, while the giant magnetoresistance of bulk and nanomaterials with various shapes is difficult to reach more than 300%. Bi microparticles with extremely high crystallinity have a longer mean free path of carriers, so they have a better giant magnetoresistance effect compared to bulk materials or nanomaterials, and the synthesis of bismuth microparticles and bismuth simple There is no literature report yet.

Contents of the invention

The invention provides a bismuth microparticle, which solves the deficiency in the background technology. The bismuth microparticle has a positive giant magnetoresistance of more than 700% at low temperature and a positive giant magnetoresistance of more than 180% at room temperature, and its preparation method is simple.

The technical scheme adopted to realize the above-mentioned purpose of the present invention is:

A bismuth micron particle, the particle is bismuth simple substance, the particle size is 1-3 μm, the particle is spherical or polyhedral, prepared by the following method: add bismuth source and template agent to ethylene glycol, stir until completely dissolved , and then adjust the pH value of the solution to greater than 10 while stirring. After the solute is completely dissolved, transfer the solution to a closed polytetrafluoroethylene-lined high-pressure reactor, and react at 160-200°C for more than 10 hours. After the end, the obtained product is centrifuged or filtered, washed to remove residual solute, dried and cooled to obtain bismuth microparticles.

The bismuth source is bismuth nitrate or bismuth acetate, the template is CTAC, or a double surfactant mixed with CTAC and PVP, and the molar ratio of the bismuth source to the template is 0.5-3:1.

The pH of the solution was adjusted to greater than 10 using KOH in ethylene glycol.

Compared with the prior art, the preparation method of the bismuth microparticles provided by the invention is simple, and the elemental bismuth crystal microparticles are prepared under alkaline conditions. Its shape is relatively uniform, spherical or polyhedral, with a particle size of 1-3 μm. The prepared bismuth microparticles have a positive giant magnetoresistance of 700% at low temperature and a giant magnetoresistance of about 180% at room temperature.

Description of drawings

Fig. 1 is the SEM photograph of the bismuth microparticle provided by the embodiment of the present invention;

Fig. 2 is the XRD figure of the bismuth microparticle provided by the embodiment of the present invention;

Fig. 3 is the magnetic field intensity-magnetoresistance curve (T=10K, 300K) of the target product.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following embodiments.

Example 1

The bismuth microparticles prepared in this example were prepared by the following method: 3 mmol bismuth nitrate and 3 mmol CTAC were added to 60 mL of ethylene glycol, stirred at 500 r/min until dissolved, and then 1 mol/L of KOH was added dropwise therein. Ethylene glycol solution, to a pH greater than 10. After obtaining a clear solution, continue stirring for 1 hour, transfer the solution to a closed polytetrafluoroethylene-lined high-pressure reactor, and place it in a blast oven at 180°C for 12 hours, take it out after natural cooling, and filter the obtained product with suction. Wash with deionized water until neutral, and use ethanol to wash away the template agent. Finally, the filtered product was vacuum-dried at 60° C. for 12 h to obtain the target product.

The field emission scanning electron microscope photo of the bismuth microparticles provided in this embodiment is shown in Figure 1, as can be seen from Figure 1, the particle diameter of the bismuth microparticles is 1 to 3 μm, and the particles are spherical or polyhedral . The XRD pattern of the bismuth microparticles prepared in this example is shown in FIG. 2 . The magnetic field strength-magnetoresistance curve of the bismuth microparticles prepared in this embodiment is shown in Figure 3, as can be seen from Figure 3, the positive giant magnetoresistance of the bismuth microparticles at low temperature (10K) is more than 700% , the positive giant magnetoresistance is above 180% at room temperature (300K).

Example 2

The bismuth microparticles prepared in this example were prepared by the following method: 3 mmol bismuth acetate and 2.5 mmol CTAC were added to 60 mL of ethylene glycol, stirred at 500 r/min until dissolved, and then 1 mol/L of KOH was added dropwise ethylene glycol solution to a pH greater than 10. After obtaining a clear solution, continue stirring for 1 hour, transfer the solution to a closed polytetrafluoroethylene-lined high-pressure reactor, and place it in a blast oven at 160°C to react for 12 hours, take it out after natural cooling, and filter the obtained product with suction. Wash with deionized water until neutral, and use ethanol to wash away the template agent. Finally, the filtered product was vacuum-dried at 60° C. for 12 h to obtain the target product.

Example 3

The bismuth microparticles prepared in this example were prepared by the following method: 3 mmol bismuth nitrate and 1 mmol CTAC were added to 60 mL of ethylene glycol, stirred at 500 r/min until dissolved, and then 1 mol/L of KOH was added dropwise Ethylene glycol solution, to a pH greater than 10. After obtaining a clear solution, continue stirring for 1 hour, transfer the solution to a closed polytetrafluoroethylene-lined high-pressure reactor, and place it in a blast oven at 160°C to react for 12 hours, take it out after natural cooling, and filter the obtained product with suction. Wash with deionized water until neutral, and use ethanol to wash away the template agent. Finally, the filtered product was vacuum-dried at 60° C. for 12 h to obtain the target product.

Example 4

The bismuth microparticles prepared in this example were prepared by the following method: 3mmol bismuth nitrate and 3mmolCTAC were added to 35mL ethylene glycol, stirred at 500r/min until dissolved, and then 1mol/L of KOH was added dropwise Ethylene glycol solution, to a pH greater than 10. After obtaining a clear solution, continue to stir for 1 hour, transfer the solution to a closed polytetrafluoroethylene-lined high-pressure reactor, and place it in a blast oven at 180 ° C for 24 hours, take it out after natural cooling, and filter the obtained product with suction. Wash with deionized water until neutral, and use ethanol to wash away the template agent. Finally, the filtered product was vacuum-dried at 60° C. for 12 h to obtain the target product.

Example 5

The bismuth microparticles prepared in this example were prepared by the following method: 3 mmol of bismuth nitrate, 3 mmol of CTAC and 1 g of PVP were added to 60 mL of ethylene glycol, stirred at 500 r/min until dissolved, and then 1 mol/L of KOH in ethylene glycol to a pH greater than 10. A clear solution was obtained, and after stirring for 1 hour, the solution was transferred to a closed polytetrafluoroethylene-lined high-pressure reactor, and placed in a blast oven at 180°C for 24 hours, cooled naturally, then taken out, and the obtained product was separated by a centrifuge For washing, the rotation speed is 1500-4000r/min, the centrifugation time is 5min, and the deionized water is used to wash until neutral, and the template agent is washed away with ethanol. Finally, the filtered product was vacuum-dried at 60° C. for 12 h to obtain the target product.

Claims (4)

1. A kind of bismuth micron particle, it is characterized in that: described particle is bismuth simple substance, and its particle diameter is 1～3 μ m, and particle is spherical or polyhedral shape, adopts following method to prepare: bismuth source and templating agent are added ethylene glycol , stirred until completely dissolved, and then adjusted the pH value of the solution to greater than 10 while stirring. After the solute was completely dissolved, the solution was transferred to a closed polytetrafluoroethylene-lined high-pressure reactor. Under the condition of reacting for more than 10 hours, after the reaction is completed, the obtained product is centrifuged or filtered, washed to remove residual solute, dried and cooled to obtain bismuth microparticles. 2. bismuth micron particle according to claim 1, is characterized in that: described bismuth source is bismuth nitrate or bismuth acetate, and described templating agent is CTAC, or the double surfactant that CTAC and PVP are mixed, The molar ratio of the bismuth source to the template agent is 0.5-3:1. 3. The bismuth microparticle according to claim 1, characterized in that: the pH value of the solution is adjusted to be greater than 10 by using KOH in ethylene glycol solution. 4. The bismuth microparticles according to claim 1, characterized in that: the positive giant magnetoresistance of the bismuth microparticles is more than 700% at low temperature, and the positive giant magnetoresistance is more than 180% at room temperature.