KR101220402B1 - The method of magnesium oxide nanorod coated with tin oxide and magnesium oxide nanorod coated with tin oxide prepared thereby - Google Patents

Abstract

The present invention relates to a method for preparing magnesium oxide nanorods coated with tin oxide for preventing pollution and oxidation and improving fluorescence characteristics, and magnesium oxide nanorods prepared thereby, more specifically magnesium nitride (Mg ₃ N ₂ ) Thermal vaporizing the powder to form magnesium oxide nanorods (step 1); Coating tin oxide (SnO ₂ ) on the magnesium oxide (MgO) nanorod formed in step 1 (step 2); The method of manufacturing a tin oxide coated magnesium oxide nanorods and the oxidation produced by the method comprising the step (step 3) of heat-treating the magnesium oxide nanorods coated with tin oxide by the step 2 in a reducing atmosphere By providing magnesium nanorods, it exhibits improved light emission characteristics, and has an effect of manufacturing excellent optoelectronic devices or electronic devices using magnesium oxide nanorods by improving lifetime and reliability.

Description

The method of magnesium oxide nanorod coated with tin oxide and magnesium oxide nanorod coated with tin oxide prepared according to the manufacturing method of magnesium oxide nanorod coated with tin oxide

The present invention relates to a method for producing magnesium oxide nanorods coated with tin oxide, and to a magnesium oxide nanorod coated with tin oxide prepared thereby.

Recently, carbon nanotubes (CNT), oxide nanotubes, nanorods, nanowires, nanosheets, nanoribbons, nanoribbons or nano-thick hollow particles (Hollow) Research into devices using various types of low-dimensional nanostructures, such as spheres, is being actively conducted. Such nanostructures have attracted great attention not only for their excellent properties such as physical and chemical properties, but also for being able to realize various effects of nanomaterials while being a basic unit useful for constructing nanodevices. .

These nanostructures are synthesized by laser ablation, sputtering, chemical vapor deposition, or sol-gel. In addition, impurities may be added to the nanostructure, or may be synthesized into a dual structure or a core-shell structure to improve its characteristics as an element. In addition, research on nano devices forming field effect transistors (FETs), lasers, chemical sensors, bio sensors, and the like using nanostructures is being conducted.

Magnesium oxide has been widely applied to heat-resistant structural materials, flame retardant materials, light transmissive materials, insulating materials, etc., due to its high heat resistance, light transmittance, and electrical insulation. Recently, it is used as a dielectric protective film material of plasma display panel (PDP) to improve the lifetime of the dielectric, and excellent secondary electron emission characteristics, which plays a big role in lowering the discharge voltage and power consumption and improving the luminous efficiency and lifetime of the phosphor. . As described above, a dielectric protective film, which is recognized as a core material of PDP, is generally applied by depositing magnesium oxide pellet (sintered body, target) on a dielectric by sputtering or two-beam method. The magnesium oxide target is manufactured by sintering magnesium oxide powder at high temperature to form a compact sintered body, and by growing and crushing magnesium oxide single crystal to make a target of a certain size. Polycrystalline magnesium oxide sintered bodies made of magnesium powder as raw materials have been reported to have excellent properties.

Existing commercially available magnesium oxide nanoparticles are generally prepared by a sol-gel method using hydrolysis and polycondensation of magnesium alkoxides. Mn ^{3 +} ion, which is a transition element of about 10 ppmw, contained no photoluminescence phenomenon, and only one zero phonon line (ZPL) emission peak was observed in the case of bulk magnesium oxide. However, by adding a heat treatment process for burning the material in the air, a method for producing magnesium oxide nanoparticles having a characteristic of exhibiting two sharp ZPL emission peaks while maintaining an excited state has been developed [Korea Patent Application Publication No. 10-2005-0090539]. ].

In order to manufacture a one-dimensional nanostructures (nanorods, nanobelts, nanoribbons, nanoneedles, etc.) of magnesium oxide having a one-dimensional structure by using various techniques such as sol-gel template method, thermalization method, and pulse laser deposition method. Techniques have been studied. However, the nanostructures manufactured by the above method have a short lifespan because they do not have a protective film, are vulnerable to contamination, and have oxidation. Accordingly, the present inventors completed the present invention by confirming that the protective layer is coated on the magnesium oxide nanorods and then heat treated to prevent contamination and oxidation and to improve fluorescence characteristics.

An object of the present invention is to provide a method for producing magnesium oxide nanorods coated with tin oxide.

Another object of the present invention is to provide a magnesium oxide nanorod coated with tin oxide prepared by the production method.

In order to achieve the above object, the present invention comprises the steps of thermal vaporizing magnesium nitride (Mg ₃ N ₂ ) powder to form magnesium oxide nanorods (step 1); Coating tin oxide (SnO ₂ ) on the magnesium oxide nanorods formed in step 1 (step 2); And a step (step 3) of heat treating the magnesium oxide nanorods coated with the tin oxide in a reducing atmosphere by the step 2, which provides a method of manufacturing the magnesium oxide nanorods coated with the tin oxide.

In addition, the present invention provides a magnesium oxide nanorod coated with tin oxide prepared by the manufacturing method.

The tin oxide-coated magnesium oxide nanorods prepared according to the present invention exhibit improved light emission characteristics than the conventional magnesium oxide nanorods, and can manufacture electronic devices and optoelectronic devices using the nanorods by improving product reliability and lifespan. In this case, there is an effect of manufacturing a device having excellent performance and long life.

1 is a horizontal tube furnace for synthesizing magnesium oxide nanorods,
2 is a schematic view of atomic layer deposition equipment for synthesizing tin oxide,
3 is a SEM picture of the magnesium oxide nanorods according to the present invention,
4 is a TEM photograph of magnesium oxide nanorods according to the present invention,
5 is an X-ray diffraction graph of the synthesized magnesium oxide nanorods,
6 is a HR-TEM picture of magnesium oxide nanorods according to the present invention,
7 is an electron diffraction analysis photograph of magnesium oxide nanorods according to the present invention,
8 is a concentration profile of energy dispersive X-rays of magnesium oxide nanorods according to the present invention,
9 is a graph of luminescence spectroscopy analysis of the synthesized magnesium oxide nanorods.

Hereinafter, the present invention will be described in detail.

The present invention,

Thermal vaporizing the magnesium nitride (Mg ₃ N ₂ ) powder to form magnesium oxide nanorods (step 1);

Coating tin oxide (SnO ₂ ) on the magnesium oxide nanorods formed in step 1 (step 2); And

It provides a method of producing a tin oxide coated magnesium oxide nanorods comprising the step (step 3) of heat treating the magnesium oxide nanorods coated with tin oxide in a reducing atmosphere by the step 2.

Hereinafter, the present invention will be described in detail for each step.

Step 1 according to the present invention uses a horizontal tube furnace to thermally vaporize the magnesium nitride powder to form magnesium oxide nanorods. The horizontal tube furnace is shown in FIG. 1 and will be described in detail based on this. Alumina boat (3) containing magnesium nitride powder (5) is placed in the center of the quartz tube (2), and the silicon (Si) (4) substrate is positioned with the gold-coated surface facing down. The gas flow rate inside the horizontal tube furnace is set to 300 cubic centimeters per minute (N ₂ ) and 10 sccm of oxygen (O ₂ ) .The pressure is 1 Torr and the temperature in the horizontal furnace (1) zone is Maintain at 800 ~ 1000 ℃. After performing the thermalization process for 2 hours to prepare a magnesium oxide nanorods by cooling to room temperature.

In step 1, the magnesium oxide nanorods are formed by a vapor-liquid-solid (VLS) or vapor-solid (VS) growth mechanism. First, when the gold thin film and magnesium nitride, which are catalyst materials, are placed in a reactor and heated to a high temperature, magnesium nitride is converted into a gas phase so that gas adheres to the surface of the gold thin film, and a gold-magnesium mixed solution droplet is formed above the melting point. Afterwards, the nanowires grow in one direction from the solid-liquid boundary by the oversupply gas. Breaking the symmetry at the solid-liquid boundary by the over-supplied reaction gas is an important step in the formation of one-dimensional nanocrystals in the VLS synthesis technique. In addition, since the droplet of the mixed solution of the catalyst and the reaction gas acts as a kind of template when synthesizing the nanowires, the diameter of the synthesized nanowires can be controlled by controlling the size of the catalyst particles. Since the length of the nanowires is proportional to the reaction time, the nanowire length can also be controlled.

On the other hand, the VS mechanism means that the nanowires grow only in one direction due to the reaction gas binding to a specific crystal plane or the increase of reactivity toward a specific crystal plane in the nanowire synthesis, and the main mechanism of the anisotropic growth mechanism It is content. A differential defect-induced growth model is one in which reaction gases are better bound to a specific defect causing growth in one direction. While this VS growth mechanism is not clearly described in all cases, it is a useful technique for forming various types of nanostructures (nanoribbons, tetrapods, combs).

The one-dimensional structure of the magnesium oxide nanostructure of step 1 can be prepared by the VLS or VS growth mechanism using magnesium nitride as a precursor.

Magnesium oxide can be obtained by direct reaction of magnesium nitride with oxygen.

(Reaction 1) 2Mg ₃ N ₂ (s) + 3O ₂ (g) → 6MgO (s) + 2N ₂ (g)

Otherwise, magnesium nitride having a decomposition temperature of 800 ° C. is decomposed into magnesium vapor at a substrate temperature of 900 ° C.

(Reaction 2) Mg ₃ N ₂ (s) → ₃ Mg (g) + N ₂ (g)

(Reaction 3) Mg (s) + O ₂ (g) ↔ 2MgO (s)

The decomposed magnesium vapor reacts with oxygen gas to form magnesium oxide nanorods, and the reaction 3 is a reaction in which the production and decomposition of magnesium oxide are simultaneously performed.

In fact, the formation of magnesium oxide from the magnesium nitride precursor can be judged to be formed on the surface of the alumina boat through reactions 2 and 3 as a magnesium oxide layer, which is magnesium oxide nano because the reaction temperature of reactions 2 and 3 is lower than reaction 1 The rod is grown to the nucleus of the magnesium oxide layer by reaction 1.

In the step 1, the thermalization process is preferably using a gold (Au) thin film as a catalyst. At this time, the gold thin film is deposited on the Si substrate by an RF magnetron sputter to a thickness of 3nm, Au ⁺ ions diffuse into the magnesium oxide nanorods from the gold thin film used as a catalyst. The blue light is improved in the fluorescence characteristics of the magnesium oxide nanorods because the density of the surface state of the tin oxide is reduced due to the coating of tin oxide. Therefore, it is possible to use magnesium oxide nanorods as fluorescent materials for displays such as LEDs and PDPs.

Step 2 according to the present invention is a step of coating tin oxide on the magnesium oxide nanorods formed in step 1. It is preferable to use a chemical vapor deposition method, an atomic layer deposition method, a sputtering method, etc., and it is more preferable to use an atomic layer deposition method. When tin oxide is coated using the atomic layer deposition method, it is possible to evenly coat tin oxide on the surface of the magnesium oxide nanorods.

The atomic layer deposition (ALD) technology is a deposition method capable of controlling the thickness of a single atomic layer by using a reaction consisting of a process of chemisorption and desorption on a substrate surface. ALD is similar to conventional chemical vapor deposition (CVD) in terms of chemical reaction. However, unlike CVD in which two or more reactants are mixed in a reactor and react in the gas phase under the conditions of temperature and pressure, or at the substrate surface, precursor materials are sequentially introduced into the reactor once during the ALD reaction. Injecting only one reaction gas into the reactor and removing the precursor remaining after the reaction through the inert gas.

Step 3 according to the present invention is a step of heat-treating the magnesium oxide nanorods coated with tin oxide by the step 2 in a reducing atmosphere, it is possible to improve the light emission characteristics of the magnesium oxide nanorods through the heat treatment. The heat treatment is a reducing atmosphere N ₂ It is an atmosphere formed by a mixed gas of / 3 mol% H ₂ , it is preferably carried out at a temperature of 400 ~ 700 ℃. If the temperature of the heat treatment is less than 400 ℃ tends to improve the degree of improvement of the light emission characteristics, if the temperature exceeds 700 ℃ there is a disadvantage that the crack in the tin oxide film may occur.

In addition,

It provides a magnesium oxide nanorods coated with tin oxide prepared according to the method. The tin oxide-coated magnesium oxide nanorods have an effect of extending the life and improving the reliability by preventing the tin oxide film is coated on the surface to prevent contamination or natural oxide film is formed. In addition, the tin oxide-coated magnesium oxide nanorod is N ₂ Heat treatment is performed in a reducing atmosphere of / 3 mol% H ₂ to show improved luminescence properties. Therefore, when the magnesium oxide nanorod coated with tin oxide is applied to an optoelectronic device and an electronic device, it is possible to manufacture an optoelectronic device and an electronic device having an improved effect on the lifetime and performance.

The thickness of the tin oxide coated on the magnesium oxide nanorods coated with tin oxide according to the present invention is preferably 2 to 10 nm, and the tin oxide is evenly coated on the entire magnesium oxide nanorods to protect the magnesium oxide nanorods therein. do. When the thickness of the tin oxide film is less than 2 nm, there is a problem in that the film is not coated locally. When the thickness of the tin oxide film is greater than 10 nm, light is absorbed by the film and thus the emission intensity of the nanorod is decreased.

Hereinafter, the present invention will be described in detail by way of examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

< Example  1> Magnesium oxide coated with tin oxide Nano-rod  Manufacturing I

Step 1. Magnesium Oxide Nanorod  Manufacturing stage

An alumina boat containing 50 g of magnesium nitride powder is placed in a horizontal tube furnace, and a Si substrate on which a 3 nm thick gold film is deposited is placed. The temperature of the furnace was maintained at 900 ℃, and the inside of the horizontal tube furnace was kept at a pressure of 1 torr while simultaneously putting 300 sccm of nitrogen gas and 10 sccm of oxygen gas. The heat vaporization was carried out for 1 hour and then cooled to room temperature to prepare magnesium oxide nanorods.

Step 2. Coating Tin Oxide

The atomic layer evaporator shown in FIG. 2 is alternately injected with tin precursor (SnCl ₄ ) and oxygen precursor (H ₂ O) every 2 seconds into the magnesium oxide nanorod prepared in step 1, and the chamber temperature is 350 ° C. The internal pressure was treated at a level of 0.1 torr and supplied with nitrogen at 100 sccm. The deposition process was performed in 1200 cycles to prepare a magnesium oxide nanorod coated with tin oxide.

Step 3. Magnesium Oxide Coated with Tin Oxide Nanorods  Step of heat treatment

Above with a magnesium oxide nanorods tin oxide coatings produced in the step 2, the heat treatment at 650 ℃ a reducing atmosphere of _{N 2/3 mol% H 2} 30 minutes to prepare a magnesium oxide nanorods tin oxide coating.

< Comparative example  1> magnesium oxide Nano-rod  Produce

Step 1 of Example 1 was carried out in the same manner to prepare magnesium oxide nanorods.

< Comparative example  2> magnesium oxide coated with tin oxide Nano-rod  Manufacture Ⅱ

Only Example 1 and 2 of Example 1 were carried out in the same manner to prepare a magnesium oxide nanorod coated with tin oxide.

< Comparative example  3> Magnesium oxide coated with tin oxide Nano-rod  Manufacturing III

Except for heat treatment in an argon atmosphere instead of a reducing atmosphere in step 3 of Example 1 was carried out in the same manner as in Example 1 to prepare a magnesium oxide nanorod coated with tin oxide.

< Comparative example  4> magnesium oxide coated with tin oxide Nano-rod  Manufacture IV

Except for heat treatment in an oxygen atmosphere instead of a reducing atmosphere in step 3 of Example 1 was carried out in the same manner as in Example 1 to prepare a magnesium oxide nanorod coated with tin oxide.

< Experimental Example  1> Scanning electron microscope SEM Shape analysis

In order to analyze the form of the magnesium oxide nanorods coated with zinc oxide film, the zinc oxide coated magnesium oxide nanorods prepared in Example 1 were analyzed by SEM, and the results are shown in FIG. 3.

As shown in Figure 3, Comparative Examples 1 and 2 are the SEM (FESEM, SEM) of magnesium oxide nanorods prepared by thermalization at 900 ℃ and magnesium oxide nanorods coated with tin oxide using ALD to the magnesium oxide nanorods Field emission scanning electron microscopy) shows that the nanorod tip particles are nanorods formed by the VLS mechanism. Statistically, the diameter of the magnesium oxide nanorods was 100-180 nm.

< Experimental Example  2> transmission electron microscope TEM State analysis using

In order to analyze the state of the magnesium oxide nanorods coated with the tin oxide film, the zinc oxide coated magnesium oxide nanorods prepared in Example 1 were analyzed using TEM, and the results are shown in FIG. 4.

As shown in FIG. 4, the low magnification TEM image of the magnesium oxide coated with the tin oxide film is an equiaxed nanorod, and the magnesium oxide is positioned inside and the tin oxide film is evenly coated with a thickness of 2 to 10 nm on the outside.

< Experimental Example  3> X-ray diffraction  Analysis of Crystal Structure

X-ray diffraction (XRD) analysis was performed on the zinc oxide-coated magnesium oxide nanorods prepared in Comparative Examples 2 and 1 to confirm the change in crystal structure due to heat treatment. XRD equipment was Rigaku DMAX 2500, using a Cu-Kα line with an incident angle of 0.5 °, the results are shown in FIG.

As shown in FIG. 5, the magnesium oxide nanorods coated with the tin oxide film are changed by heat treatment in an argon atmosphere. In the spectrum before heat treatment, the peak except for the peak related to gold is a peak of magnesium oxide and has a cubic structure (fcc, faced-centered cubic) structure. In addition, the spectrum after the heat treatment showed that the peak indicating the tetragonal crystals of SnO ₂ was not before the heat treatment. Accordingly, it can be seen from FIG. 5 that the tin oxide is not crystallized unless the tin oxide film-coated magnesium oxide nanorod is heat treated, but after the heat treatment, the crystalline mixture of the cubic structure and the tetragonal structure becomes a structure.

< Experimental Example  4> internal and surface analysis

In order to analyze the internal and surface morphology of the tin oxide film-coated tin oxide nanorods, the zinc oxide-coated magnesium oxide nanorods prepared in Example 1 were prepared by using a high-resolution transmission electron microscope (HR-TEM). The shape of was observed with respect to the white square part of FIG. 3, and the result is shown in FIG.

As shown in FIG. 6, it can be seen that there are two crystal structures, the interplanar spacing of tin oxide for {112} is 0.331 nm, and the interplanar spacing of magnesium oxide for {111} is 0.243 nm. there was.

< Experimental Example  5> Electronic diffraction analysis  Crystal structure check

In order to analyze the crystal structure of the zinc oxide coated magnesium oxide nanorods prepared in Example 1 was analyzed through a selected area (electron) diffraction (SAD) embedded in the TEM, the results are shown in FIG.

As shown in Figure 7, the pattern of the SAD shows that not only cubic system but also cubic structure coexist.

< Experimental Example  6> EDXS Energy distribution analysis

In order to determine the degree of energy dispersion, the zinc oxide-coated magnesium oxide nanorods prepared in Comparative Examples 2, 4, and Example 1 were analyzed by using electron diffraction x-ray spectroscopy (EDXS), and the results are illustrated in FIG. 8. Shown in

As shown in FIG. 8, it can be seen that the magnesium concentration ratio to the oxygen concentration of the nanorods (Comparative Example 4) heat-treated in an oxygen atmosphere is greater than the nanorods (Comparative Example 2) which are not heat treated. This is because a large amount of oxygen enters the oxygen vacancies in the center of the magnesium oxide nanorod through the tin oxide film in the oxygen atmosphere. In addition, it can be seen that the ratio of magnesium concentration to oxygen concentration of the nanorods heat-treated in the reducing atmosphere (Example 1) is larger than the nanorods heat-treated in the oxygen atmosphere (Comparative Example 4). This is because oxygen is released into gaseous water by the reaction between oxygen and hydrogen gas and oxygen vacancies are formed.

< Experimental Example  7> Luminescence spectroscopy  Color and intensity analysis

In order to determine the color and intensity of light, the zinc oxide-coated magnesium oxide nanorods prepared in Comparative Examples 2, 4, and Example 1 were analyzed using a light spectrometer (PL), and the results are shown in FIG. 9. It was. At this time, the height of the peak represents the intensity of light emitted and the wavelength of the peak represents the color of light emitted. In other words, the higher and narrower the peak, the higher the luminance of the emitted light.

As shown in FIG. 9, the tin oxide-coated magnesium oxide nanorods were mainly composed of orange light around 600 nm. At this time, the nanorods heat-treated in a reducing atmosphere composed of a mixed gas of nitrogen and hydrogen (Example 1) exhibited the strongest luminous efficiency, and the nanorods heat-treated in the oxygen atmosphere (Comparative Example 4) did not undergo heat treatment. Although the luminous efficiency was stronger than that of the nanorods (Comparative Example 2), the luminous efficiency was lower than that of the heat treatment in the reducing atmosphere (Example 1).

1: horizontal heating furnace 2: quartz tube
3: alumina boat 4: Si substrate
5: magnesium nitride

Claims (7)

Using magnesium nitride (Mg ₃ N ₂ ) powder deposited on a substrate as a catalyst to thermally vaporize it under oxygen supply to form magnesium oxide nanorods (step 1);
Coating tin oxide (SnO ₂ ) on the magnesium oxide (MgO) nanorods formed in step 1 (step 2); And
A step (step 3) of heat-treating the magnesium nanorods coated with oxide of tin oxide by the step ₂ N 2/3 in a mol% H ₂ in a reducing atmosphere that the composition by mixing the gas in a temperature range of 400 to 700 ℃ Method for producing a magnesium oxide nanorod coated with tin oxide for a light emitting device, characterized in that.
delete The tin oxide coating of claim 1, wherein the tin oxide coating of step 2 is performed by a method selected from the group consisting of chemical vapor deposition, atomic layer deposition, and sputtering. Method of manufacturing magnesium nanorods.
delete delete Magnesium oxide nanorods coated with a tin oxide for a light emitting device, which is prepared by the method of claim 1.
The tin oxide film coated with magnesium oxide nanorods according to claim 6, wherein the tin oxide film coated on the magnesium oxide nanorods has a thickness of 2 to 10 nm.

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