Magnesium oxide-based compound and preparation method thereof

Abstract

The present invention relates to a magnesium oxide-based composite comprising ytterbium (Yb) element and magnesium oxide (MgO) grains, and a method for preparing the same.

Description

Technical Field

[0001] This invention relates to a magnesium oxide-based composite and its preparation method. Background Technology

[0002] Electronic devices consist of electronic components such as laminates, printed circuit boards, and multilayer circuit boards. Recent electronic devices incorporate high-power components and are manufactured with high-density internal structures, thus requiring higher levels of heat dissipation and moisture resistance than before. The fillers used in traditional semiconductor packaging resin compositions are primarily silicon dioxide and alumina. However, silicon dioxide, due to its low thermal conductivity, has insufficient heat dissipation capacity to cope with the increased heat generation caused by high integration, high power, and high speed, thus posing a drawback for the stable operation of semiconductors. On the other hand, while alumina, with its higher thermal conductivity than silicon dioxide, improves heat dissipation, its excessive hardness leads to severe wear on mixing machines, molding machines, and molds.

[0003] Therefore, magnesium oxide, which has a higher thermal conductivity than silicon dioxide and aluminum oxide, is being studied as a material for resin fillers in semiconductor packaging. However, because magnesium oxide powder is more hygroscopic than silicon dioxide powder, it is difficult to maintain stable physical properties. Specifically, when magnesium oxide powder is used as a resin filler in semiconductor packaging, magnesium oxide reacts with moisture in the air to form magnesium hydroxide on the surface of the magnesium oxide, causing the filler to expand in volume, which can lead to cracking and decreased thermal conductivity. Therefore, it is necessary to study how to improve the moisture resistance of magnesium oxide to ensure long-term physical property stability.

[0004] [Existing Technical Documents]

[0005] Korean Patent Publication No. 10-1878963 Summary of the Invention

[0006] Technical issues

[0007] The present invention aims to provide a magnesium oxide-based composite that can improve the low moisture resistance of existing magnesium oxide to ensure long-term physical property stability, and a method for preparing the same.

[0008] However, the problems to be solved by the present invention are not limited to those mentioned above, and other problems not mentioned are clearly understood by those skilled in the art from the following description.

[0009] Technical solution

[0010] One embodiment of the present invention provides a magnesium oxide-based composite containing ytterbium (Yb) and magnesium oxide (MgO) grains.

[0011] Another embodiment of the present invention provides a method for preparing the magnesium oxide-based composite. Specifically, a method for preparing a magnesium oxide-based composite comprising the following steps is provided: (A) preparing a sintering mixture comprising magnesium oxide or a magnesium oxide precursor and ytterbium oxide; (B) pretreating the sintering mixture, the pretreatment comprising at least one of coating, granulation, stamping and injection molding; and (C) sintering the sintering mixture to form crystals.

[0012] Another embodiment of the present invention provides an organic-inorganic complex formed by dispersing particles of the magnesium oxide-based composite within a polymer matrix.

[0013] Invention Effects

[0014] The magnesium oxide-based composite of one embodiment of the present invention has excellent moisture resistance, which can solve the problems of poor physical properties caused by the low moisture resistance of existing magnesium oxide.

[0015] The effects of this invention are not limited to those mentioned above, and other effects not mentioned are clearly understood by those skilled in the art from the following content. Attached Figure Description

[0016] Figure 1 An example of the evaluation criteria at different sintering temperatures according to the embodiments and comparative examples is shown.

[0017] Figure 2 The weight gain rate after moisture absorption resistance test according to the Yb2O3 content and sintering temperature in Examples 1 to 11 is shown.

[0018] Figure 3 SEM images of the composites according to Examples 6 to 11 are shown at a sintering temperature of 1550°C.

[0019] Figure 4 The results of surface EDS analysis at the grain locations of the composite prepared according to the examples are shown.

[0020] Figure 5 The results of surface EDS analysis of the regions located at grain boundaries in the composites prepared according to the examples are shown.

[0021] Figure 6 Show Figure 5 The EDS mapping results of regions located at grain boundaries as independent phases.

[0022] Figure 7 The XRD analysis results of the composite according to Example 3 before and after the moisture resistance test are shown at a sintering temperature of 1550°C.

[0023] Figure 8 The XRD analysis results of the composite according to Example 6 before and after the moisture resistance test are shown at a sintering temperature of 1550°C.

[0024] Figure 9 SEM images of the composite surface of Example 6 at different sintering temperatures are shown. Detailed Implementation

[0025] The present invention will now be described in detail.

[0026] This invention can be modified in various ways and can have multiple embodiments. Specific embodiments will be illustrated in the accompanying drawings and described in detail in the text.

[0027] However, this is not to limit the invention to a specific embodiment, but should be understood to include all modifications, equivalents, and substitutions within the scope of the invention's concept and technology. In describing the invention, detailed descriptions of relevant prior art are omitted when it is determined that such descriptions may obscure the essence of the invention.

[0028] The terminology used in this specification is for describing specific embodiments only and is not intended to limit the scope of the invention. Unless the context clearly indicates otherwise, singular expressions include plural expressions.

[0029] In this specification, when it is said that a part "includes" a certain component, it means that other components are not excluded, and may be included, unless otherwise stated to the contrary.

[0030] In this specification, when it is said that a component is located "on" other components, this includes not only the case where the component is connected to other components, but also the case where there are other components between the two components.

[0031] In this specification, ytterbium oxides include ytterbium(II) (YbO) and ytterbium(III) (Yb2O3), specifically ytterbium(III).

[0032] The present invention will now be described in detail.

[0033] One embodiment of the present invention provides a magnesium oxide-based composite containing ytterbium (Yb) and magnesium oxide (MgO) grains.

[0034] The magnesium oxide-based composite of the present invention is characterized by the inclusion of ytterbium (Yb) in the magnesium oxide-based matrix. Due to the presence of ytterbium (Yb), the magnesium oxide-based composite of the present invention can significantly reduce or prevent the formation of magnesium hydroxide on the surface of magnesium oxide due to the absorption of moisture from the air. Therefore, the magnesium oxide-based composite of the present invention has the advantage of overcoming the limitation in the use of existing magnesium oxides due to their low moisture absorption resistance. Furthermore, the presence of ytterbium (Yb) in the magnesium oxide-based composite of the present invention also allows for a lower sintering temperature during preparation, thereby reducing manufacturing costs.

[0035] The magnesium oxide-based composite of the present invention can be a sintered body, using magnesium oxide containing ytterbium (Yb) as the base material, and can be a ceramic using magnesium oxide as the base material. Alternatively, the magnesium oxide-based composite of the present invention can be a solid solution containing ytterbium (Yb) within the crystalline structure of magnesium oxide. Furthermore, the magnesium oxide-based composite of the present invention can be a solid solution containing ytterbium (Yb) and other metallic elements within the crystalline structure of magnesium oxide.

[0036] According to one embodiment of the present invention, the ytterbium (Yb) element can replace the magnesium (Mg) element position in the magnesium oxide (MgO) crystal. More specifically, the ytterbium (Yb) element can replace Mg in the unit lattice of the magnesium oxide grain. 2+ At least a portion of Yb 2+ or Yb 3+ .

[0037] Furthermore, according to one embodiment of the present invention, the ytterbium (Yb) element may be contained in the form of ytterbium oxide at the interface and / or surface of the magnesium oxide (MgO) crystal. Specifically, the ytterbium oxide may exist as another phase at the magnesium oxide grain boundary. In this case, the ytterbium oxide may exist irregularly on the surface of the magnesium oxide-based composite.

[0038] According to one embodiment of the present invention, the ytterbium (Yb) element, while replacing the magnesium (Mg) element position in the magnesium oxide (MgO) crystal, may also be contained in the form of ytterbium oxide on the surface of the magnesium oxide (MgO) crystal.

[0039] According to one embodiment of the present invention, the content of ytterbium (Yb) relative to magnesium (Mg) (100 atomic percent of Mg) can be 0.02 atomic percent to 6 atomic percent. Specifically, the content of ytterbium (Yb) relative to magnesium (Mg) can be 0.02 atomic percent to 5 atomic percent, 0.02 atomic percent to 4 atomic percent, 0.02 atomic percent to 3 atomic percent, 0.02 atomic percent to 2 atomic percent, 0.04 atomic percent to 2 atomic percent, 0.04 atomic percent to 0.4 atomic percent, 0.1 atomic percent to 2 atomic percent, 0.09 atomic percent to 0.5 atomic percent, or 0.1 atomic percent to 0.4 atomic percent. When the content of ytterbium (Yb) is within the aforementioned range, the moisture resistance of the magnesium oxide-based composite can be greatly improved, thereby reducing the sintering temperature during preparation. In addition, when the content of the ytterbium (Yb) element is less than the specified range, the effect of improving the moisture resistance of the magnesium oxide-based composite will be insufficient. When the content of the ytterbium (Yb) element exceeds the specified range, the growth of magnesium oxide grains will be hindered due to the ytterbium (Yb) element or ytterbium oxide.

[0040] The content of the ytterbium (Yb) element can be measured according to methods known in the industry, such as energy dispersive spectroscopy (EDS), wavelength dispersive spectroscopy (WDS), electron probe microanalysis (EPMA), X-ray fluorescence spectroscopy (XRF), or Rietveld refinement of neutron and X-ray diffraction. Alternatively, it can be measured by inductively coupled plasma (ICP) analysis.

[0041] According to one embodiment of the present invention, the magnesium oxide-based composite may further include at least one other metallic element selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er and Al.

[0042] The other metallic elements may be derived from at least one other additive selected from the group consisting of oxides, hydroxides or carbonates, wherein the oxides, hydroxides or carbonates comprise at least one selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er and Al.

[0043] Specifically, as described above regarding ytterbium (Yb), the other metal elements may replace the magnesium (Mg) element position in the magnesium oxide (MgO) crystal and / or be located on the surface of the magnesium oxide (MgO) crystal in the form of other oxides or compounds (e.g., oxides of other metals; oxides of ytterbium (Yb) with other metals; oxides of magnesium with other metals; oxides of magnesium, ytterbium (Yb) and other metals; and at least one of their reactive oxide (compound) forms). These other metal elements may be applied together with the ytterbium (Yb) element to the magnesium oxide-based composite to improve moisture resistance and / or reduce sintering temperature, thereby saving manufacturing costs.

[0044] According to one embodiment of the present invention, the content of the other metal elements relative to the magnesium (Mg) element may be 0.02 atomic% to 5 atomic% or less. Specifically, the content of the other metal elements relative to the magnesium (Mg) element may be 0.02 atomic% to 5 atomic% or less, 0.02 atomic% to 4 atomic% or less, 0.02 atomic% to 3 atomic% or less, 0.02 atomic% to 2 atomic% or less, 0.02 atomic% to 1 atomic% or less, 0.05 atomic% to 5 atomic% or less, 0.05 atomic% to 4 atomic% or less, 0.05 atomic% to 3 atomic% or less, 0.05 atomic% to 2 atomic% or less, 0.05 atomic% to 1 atomic% or less, 0.05 atomic% to 0.5 atomic% or less, or 0.1 atomic% to 0.5 atomic% or less.

[0045] According to one embodiment of the present invention, when the magnesium oxide-based composite further comprises the other metal elements, the content of ytterbium (Yb) relative to magnesium (Mg) can be 0.02 atomic% to 1 atomic%, 0.02 atomic% to 0.5 atomic%, 0.02 atomic% to 0.25 atomic%, 0.02 atomic% to 0.15 atomic%, or 0.02 atomic% to 0.1 atomic%. When the magnesium oxide-based composite further comprises the other metal elements, the content of ytterbium (Yb) can be less than that of ytterbium (Yb) alone. When the magnesium oxide-based composite further comprises the other metal elements, the content of ytterbium (Yb) within the aforementioned range can not hinder or promote the growth of magnesium oxide grains in the magnesium oxide-based composite, thereby greatly improving moisture resistance.

[0046] According to one embodiment of the present invention, the weight gain of the magnesium oxide-based composite after a 72-hour moisture resistance test at 85°C and 85%RH is less than 1%. Specifically, the weight gain of the magnesium oxide-based composite after a 72-hour moisture resistance test at 85°C and 85%RH is less than 0.7% or less than 0.5%. For existing magnesium oxide, the weight gain after the moisture resistance test generally exceeds 10%, and even with an increase in sintering temperature, the weight gain exceeds 1%. In contrast, the magnesium oxide-based composite of the present invention shows a significantly improved moisture resistance compared to existing magnesium oxide.

[0047] According to one embodiment of the present invention, the content of magnesium oxide grains may be at least 90% by weight relative to the entire composite. Specifically, the content of magnesium oxide grains may be at least 92% by weight or 95% by weight relative to the entire composite.

[0048] According to one embodiment of the present invention, the magnesium oxide-based composite can be particles or structures of a specific shape having any of the following shapes: amorphous, spherical, elliptical, donut-shaped, and plate-like. Furthermore, the magnesium oxide-based composite can be in powder, film, or a specific bulk shape. Additionally, the magnesium oxide-based composite can be micro-particles or particulate powder having any of the following shapes: amorphous, spherical, elliptical, donut-shaped, and plate-like. When the magnesium oxide-based composite of the present invention is in powder form, it can have a particle size of 1 μm to 200 μm, or 2 μm to 150 μm. The particle size may refer to the average particle size of the powder.

[0049] The structure of a specific shape may be a structure formed by means of a mold used to achieve the specific shape.

[0050] Another embodiment of the present invention provides a method for preparing the aforementioned magnesium oxide-based composite.

[0051] Specifically, another embodiment of the present invention provides a method for preparing a magnesium oxide-based composite, comprising: (A) preparing a sintering mixture comprising magnesium oxide or a magnesium oxide precursor and ytterbium oxide; (B) pretreating the sintering mixture, the pretreating including at least one of coating, granulation, stamping and injection molding; and (C) sintering the sintering mixture to form crystals.

[0052] According to one embodiment of the present invention, the magnesium oxide precursor may include at least one of magnesium hydroxide powder, magnesium bicarbonate powder, magnesium carbonate powder, and magnesium oxide (MgO) powder.

[0053] According to one embodiment of the present invention, the method may further include: (A1) the step of dispersing the sintering mixture in a solvent. Specifically, this may involve adding the magnesium oxide precursor, ytterbium oxide, and optionally other additives described later into the solvent for dispersion and dissolution. As an example, when the magnesium oxide precursor is magnesium hydroxide powder, magnesium bicarbonate powder, and / or magnesium carbonate powder, the solvent may be water (distilled water). As yet another example, when the magnesium oxide precursor is magnesium oxide (MgO) powder, an organic solvent may be used to prevent reaction with water. The organic solvent may include, for example, anhydrous alcohols such as ethanol, methanol, and propanol; however, it is not limited thereto, and any organic solvent within the scope that does not affect the purpose and effect of the present invention may be used without limitation.

[0054] According to one embodiment of the present invention, the sintering mixture may further include a binder and / or a dispersant. The binder and / or dispersant may be further contained in the solvent and dispersed and dissolved therein.

[0055] According to one embodiment of the present invention, the binder may be an organic binder, which, when used, can be burned through sintering, thereby leaving no residue in the final magnesium oxide-based composite. Organic binders commonly used in the art can be used without limitation, and the organic binder may include at least one selected from the group consisting of cellulose binders, polyvinyl alcohol, polyvinylpyrrolidone, polyethylene glycol, gel binders, and starch.

[0056] According to one embodiment of the present invention, the dispersant may be added to make the constituent components added to the solvent uniformly dispersed, and commonly used dispersants in the art can be used without limitation. For example, ammonium polycarboxylate salts and ammonium alkyl alcohol salts can be used.

[0057] According to one embodiment of the present invention, step A1 can utilize a physical mixing method such as a ball mill to uniformly mix the components in the solvent. When a ball mill is used in step A1, it not only achieves the effect of homogeneously mixing the components in the solvent, but also has the advantage of being able to adjust the powder dispersed in the solvent to a more uniform size.

[0058] According to one embodiment of the present invention, the coating in step B is applicable to cases where the final magnesium oxide-based composite needs to be disposed on the surface of a specific electronic component or needs to be formed into a plate shape. Furthermore, the granulation in step B is applicable to cases where the final magnesium oxide-based composite needs to be formed into spherical particles. Additionally, the stamping in step B can be a method of forming by applying a predetermined pressure after placing the sintering mixture in a specific mold, and can employ various methods commonly used in the art. Further, the injection molding in step B can include any one of the following: slip casting method where the sintering mixture is formed into a slurry and then injected into a mold; injection molding method where the sintering mixture is formed into a slurry and then injected into an extruder, etc.; and cast molding method where the sintering mixture is poured into a mold for forming.

[0059] According to one embodiment of the present invention, step B may involve granulating the sintering mixture and then molding it into a specific shape. Specifically, step B may involve granulating the sintering mixture and then stamping or injection molding it. This allows for adjustment of the particle size and other properties of the sintering mixture before sintering, thereby shaping the sintered mixture into the desired shape.

[0060] According to one embodiment of the present invention, the granulation can be performed by spray drying the sintering mixture. When the spray drying method is used, more homogeneous particles with controlled particle size can be formed, thus having the advantage of being able to prepare magnesium oxide-based composites with spherical microparticles in a simple manner.

[0061] According to one embodiment of the present invention, the ytterbium oxide can function as a precursor of the ytterbium (Yb) element in the aforementioned magnesium oxide-based composite. According to one embodiment of the present invention, the content of the ytterbium oxide relative to 1 mole of magnesium oxide in the final magnesium oxide-based composite may be 0.01 mol% to 3 mol%. Specifically, relative to 1 mole of magnesium oxide in the final magnesium oxide-based composite, the ytterbium oxide may be 0.01 mol% to 2.5 mol%, 0.01 mol% to 2 mol%, 0.01 mol% to 1.5 mol%, 0.01 mol% to 1 mol%, 0.02 mol% to 1 mol%, 0.02 mol% to 0.2 mol%, 0.05 mol% to 1 mol%, 0.045 mol% to 0.25 mol%, or 0.05 mol% to 0.2 mol%. When the content of the ytterbium oxide is adjusted as described above, the content of the ytterbium (Yb) element in the magnesium oxide-based composite can also be adjusted as previously mentioned.

[0062] According to one embodiment of the present invention, the sintering mixture may further comprise at least one other additive selected from the group consisting of oxides, hydroxides, or carbonates, wherein the oxides, hydroxides, or carbonates comprise at least one selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er, and Al. Specifically, the other additive may be selected from TiO2, Ti(OH)4, and Ti(CO3). 2、 Nb2O5, ZrO2, Zr(OH)4, Zr(CO3) 2、 Ga2O3, B2O3, Fe2O3, SnO2, MnO2, Mn2O3, SiO2, V2O5, V2O3, VO2, VO, V(OH)5, V2(CO3) 5、 At least one of the group consisting of Ta2O5, Sb2O5, Y2O3, Eu2O3, Al2O3, Al(OH)3, and Al2(CO3)3. The other additives may be precursors of other metallic elements in the aforementioned magnesium oxide-based composite.

[0063] According to one embodiment of the present invention, the content of the other additives relative to 1 mole of magnesium oxide in the final magnesium oxide-based composite may be 0.01 mol% to 1 mol%. Specifically, relative to 1 mole of magnesium oxide in the final magnesium oxide-based composite, the other additives may be 0.02 mol% to 1 mol%, 0.02 mol% to 0.5 mol%, 0.02 mol% to 0.25 mol%, 0.02 mol% to 0.15 mol%, or 0.02 mol% to 0.1 mol%. When the content of the other additives is adjusted as described above, the content of other metal elements in the magnesium oxide-based composite may also be adjusted as previously mentioned.

[0064] According to one embodiment of the present invention, the total content of the ytterbium oxide and the other additives relative to 1 mole of magnesium oxide in the final magnesium oxide-based composite may be 0.01 mol% to 10 mol% or less. Specifically, when the other additives are also included, the total content of the ytterbium oxide and the other additives relative to 1 mole of magnesium oxide in the final magnesium oxide-based composite may be 0.01 mol% to 5 mol%, 0.01 mol% to 3 mol%, 0.01 mol% to 2 mol%, 0.02 mol% to 1 mol%, or 0.1 mol% to 0.5 mol%.

[0065] The content of the ytterbium oxide or the other additives is limited based on the magnesium oxide in the final magnesium oxide-based composite. This is to adjust the content of the ytterbium oxide regardless of the type of magnesium oxide precursor, since in the case of magnesium salts such as magnesium hydroxide powder, magnesium bicarbonate powder, and magnesium carbonate powder, they are all converted into the magnesium oxide phase by sintering.

[0066] According to one embodiment of the present invention, the sintering temperature in step C can be from 1000°C to 1800°C. Specifically, the sintering temperature can be adjusted according to the content of the ytterbium oxide. Depending on the content of the ytterbium oxide, the sintering temperature can be 1250°C to 1800°C, 1350°C to 1800°C, 1400°C to 1800°C, 1400°C to 1700°C, 1400°C to 1600°C, 1500°C to 1700°C, or 1500°C to 1600°C. Furthermore, when the ytterbium oxide is used together with the other additives, the sintering temperature in step C can be adjusted to a lower sintering temperature, such as 1000°C to 1500°C, 1200°C to 1600°C, or 1250°C to 1450°C, as the diffusion rate increases.

[0067] Another embodiment of the present invention provides an organic-inorganic complex formed by dispersing particles of the magnesium oxide-based composite within a polymer matrix.

[0068] According to one embodiment of the present invention, the polymer matrix may be formed from at least one resin selected from the group consisting of silicone-based resins, polyurethane-based resins, epoxy-based resins, and thermoplastic resins. The silicone-based resin, polyurethane-based resin, epoxy-based resin, and thermoplastic resin may be materials commonly used in the industry for forming the matrix. For example, the thermoplastic resin may include polyolefin resins and polyester resins. Additionally, the thermoplastic resin may include at least one of the following: general-purpose plastics such as polyethylene (PE), polypropylene (PP), polymethyl methacrylate (PMMA), polystyrene (PS), and acrylonitrile-butadiene-styrene (ABS); engineering plastics such as polybutylene terephthalate (PBT), polycarbonate (PC), polyphenylene ether (PPO), polyoxymethylene (POM), and nylon; super engineering plastics such as polyphenylene sulfide (PPS), polyimide (PI), polytetrafluoroethylene (PTFE), and polyetheretherketone (PEEK); and environmentally friendly plastics such as polybutylene adipate (PBAT) and polylactic acid (PLA).

[0069] According to one embodiment of the present invention, the magnesium oxide-based composite can be used as at least one of the following: thermally conductive material, heat dissipation material, wear-resistant material, insulating material, flame-retardant material, and reinforcing material. Specifically, the magnesium oxide-based composite has excellent thermal conductivity and moisture resistance, and therefore can be used as a heat dissipation layer or heat dissipation filler in semiconductor devices. However, it is not limited to this; it can be applied in the existing application fields of alumina and / or silicon dioxide. More broadly, it can be used without restriction as a polymer resin-based thermally conductive material, wear-resistant material, insulating material, flame-retardant material, and reinforcing material.

[0070] Preferred Implementation

[0071] The following detailed description provides examples to illustrate the invention. However, the embodiments of the invention can be modified in various ways and should not be construed as limiting the scope of the invention to the embodiments described below. The embodiments in this specification are provided to provide a more complete description of the invention to those skilled in the art.

[0072] Examples 1 to 13

[0073] Mg(OH)₂ powder (as a magnesium precursor), Yb₂O₃ powder, polyvinyl alcohol (PVA) as a binder, and ammonium polycarboxylate as a dispersant were added to distilled water and stirred to disperse and dissolve, thus preparing a mixture. The content of Yb₂O₃ powder was adjusted as shown in Table 1. Subsequently, the prepared mixture was further mixed and pulverized using a ball mill with ZrO₂ beads to prepare a slurry with a solid content of 20% by volume. Granulation was then carried out using spray drying at 230°C and 10,000 rpm. The granulated particles were then sintered at the temperatures shown in Table 1 to prepare a magnesium oxide-based composite. Furthermore, the moisture resistance of the prepared composite was tested for 72 hours at 85°C and 85% RH, and its weight gain is shown in Table 2. Table 2 also shows the content (atomic %) of Yb and other metal elements relative to Mg in the prepared composite.

[0074] Examples 14 and 15

[0075] MgO powder (as a magnesium precursor), Yb₂O₃ powder, polyvinylbutyral (PVB) resin (as a binder), and alkylammonium salt (as a dispersant) were added to ethanol and stirred to disperse and dissolve, preparing a mixture. The content of Yb₂O₃ powder was adjusted as shown in Table 1. The mixture was then further mixed and pulverized using a ball mill with ZrO₂ beads to prepare a slurry with a solid content of 20% by volume. Granulation was then performed using spray drying at 90°C and 8000 rpm. The granulated particles were then sintered at the temperatures shown in Table 1 to prepare a magnesium oxide-based composite. Furthermore, the moisture resistance of the prepared composite was tested for 72 hours at 85°C and 85% RH, and the weight gain is shown in Table 2. Table 2 also shows the Yb content (atomic %) relative to Mg in the prepared composite.

[0076] [Comparative Example 1]

[0077] Magnesium oxide sintered bodies were prepared using the same method as in Example 1, except that Yb₂O₃ powder was not used. Furthermore, the moisture resistance of the prepared sintered bodies was tested for 72 hours at 85°C and 85% RH, and the weight gain is shown in Table 2 below.

[0078] [Comparative Example 2]

[0079] Magnesium oxide sintered bodies were prepared using the same method as in Example 14, except that Yb₂O₃ powder was not used. Furthermore, the moisture resistance of the prepared sintered bodies was tested for 72 hours at 85°C and 85% RH, and the weight gain is shown in Table 2 below.

[0080] [Comparative Example 3]

[0081] Magnesium oxide sintered bodies were prepared using the same method as in Example 1, except that TiO2 and Nb2O5 were added in the amounts shown in Table 1 instead of Yb2O3 powder. Furthermore, the moisture resistance of the prepared sintered bodies was tested for 72 hours at 85°C and 85% RH, and the weight gain is shown in Table 2. Additionally, Table 2 also shows the content (atomic %) of the metal elements relative to Mg in the prepared composites.

[0082] [Table 1]

[0083]

[0084] [Table 2]

[0085]

[0086] In Table 1 above, the degree of sintering at different particle sintering temperatures is evaluated according to the following criteria.

[0087] - ××: A state in which no sintering has occurred and no grains have formed.

[0088] - ×: Only slight sintering occurs, grain growth is very low, and density is extremely insufficient.

[0089] - △: Sintering occurs to a certain extent, grain growth is low, and the density is normal or insufficient.

[0090] - ○: Sintering has occurred, the grains have grown sufficiently and are highly dense.

[0091] Figure 1 An example of the evaluation criteria at different sintering temperatures according to the embodiments and comparative examples is shown.

[0092] Figure 2 The weight gain is shown after moisture absorption resistance testing based on the Yb₂O₃ content and sintering temperature in Examples 1 to 11. (Reference) Figure 2 It can be seen that as the sintering temperature increases, the moisture resistance tends to increase accordingly. When the content of Yb2O3 relative to MgO is about 0.5 mol%, the moisture resistance tends to converge.

[0093] Figure 3 SEM images of the composites according to Examples 6 to 11 are shown, sintered at a temperature of 1550°C. (Reference) Figure 3 It was confirmed that ytterbium oxide exists as an independent phase on the surface of the prepared composite. Specifically, it was confirmed that with the increase of Yb2O3 content, the amount of ytterbium oxide existing as an independent phase on the surface of the prepared composite tends to increase, and excessive ytterbium oxide hinders grain growth, thereby leading to a decrease in the density of the sintered body.

[0094] Figure 4 The surface EDS analysis results at the grain locations of the composite prepared according to the examples are shown. Reference Figure 4 It was deduced that the crystals of the prepared composite were MgO crystals containing trace amounts of Yb.

[0095] Figure 5 The surface EDS analysis results of the regions located at grain boundaries in the composite prepared according to the examples are shown. Furthermore, Figure 6 Show Figure 5 The EDS mapping results for regions located at grain boundaries as independent phases. (Reference) Figure 5 and Figure 6 It was confirmed that the regions formed by independent phases were regions where ytterbium oxide and magnesium oxide coexisted, and it was inferred that they were ytterbium oxide grains containing trace amounts of Mg.

[0096] Figure 7 The XRD analysis results of the moisture resistance test of the composite according to Example 3 are shown before and after the test at a sintering temperature of 1550°C. Reference Figure 7 It was confirmed that the weight gain after the moisture absorption resistance test was 3.28%, and that magnesium hydroxide was formed on the surface of the composite according to Example 3 at a sintering temperature of 1550°C.

[0097] Figure 8 The XRD analysis results of the moisture resistance test of the composite according to Example 6 are shown before and after the test at a sintering temperature of 1550°C. Reference Figure 8 It was confirmed that the weight gain after the moisture resistance test was 0.47%, and no magnesium hydroxide was detected on the surface of the composite according to Example 6 at a sintering temperature of 1550°C.

[0098] Figure 9 SEM images of the composite surface of Example 6 at different sintering temperatures are shown. (Reference) Figure 9 It can be confirmed that the grain size tends to increase with increasing sintering temperature, and that due to the addition of Yb2O3, MgO grains still grow well even at lower temperatures below 1700℃.

Claims

1. A magnesium oxide-based composite comprising a ytterbium element and a magnesium oxide crystal grain.

2. The magnesium oxide-based composite according to claim 1, wherein the ytterbium element is provided to substitute for a magnesium element position of the magnesium oxide crystal.

3. The magnesium oxide-based composite according to claim 1, wherein the ytterbium element is contained on a surface of the magnesium oxide crystal in the form of ytterbium oxide.

4. The magnesium oxide-based composite according to claim 1, wherein the content of the ytterbium element is 0.02 atomic% or more and 6 atomic% or less with respect to the magnesium element.

5. The magnesium oxide-based composite according to claim 1, wherein the magnesium oxide-based composite further comprises at least one other metal element selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er, and Al.

6. The magnesium oxide-based composite according to claim 1, wherein the weight gain rate after a 72-hour hygroscopicity resistance test under an atmosphere of 85°C and 85% RH is less than 1%.

7. The magnesium oxide-based composite according to claim 1, wherein the content of the magnesium oxide crystal grain is at least 90% by weight with respect to the entire composite.

8. The magnesium oxide-based composite according to claim 1, wherein the magnesium oxide-based composite is a particle having any one of an amorphous shape, a spherical shape, an elliptical shape, a donut shape, and a plate shape, or a structure body of a specific shape.

9. A method for producing a magnesium oxide-based composite, comprising: (A) a step of preparing a sintering mixture containing a magnesium oxide or a magnesium oxide precursor, and ytterbium oxide; (B) a step of subjecting the sintering mixture to a pretreatment, the pretreatment including at least one of coating, granulation, press molding, and injection molding; and (C) a step of subjecting the sintering mixture to a sintering treatment to form a crystal.

10. The method for producing a magnesium oxide-based composite according to claim 9, wherein the content of the ytterbium oxide is 0.01 mol% or more and 3 mol% or less with respect to 1 mol of the magnesium oxide in the final magnesium oxide-based composite.

11. The method for producing a magnesium oxide-based composite according to claim 9, wherein the sintering temperature in the step (C) is 1000°C to 1800°C.

12. The method for producing a magnesium oxide-based composite according to claim 9, wherein the sintering mixture further contains at least one other additive selected from the group consisting of an oxide, a hydroxide, or a carbonate, the oxide, the hydroxide, or the carbonate containing at least one selected from the group consisting of Ti, Nb, Zr, Ga, Mn, B, Fe, Sn, Si, V, Ta, Sb, Y, Eu, Er, and Al.

13. The method for producing a magnesium oxide-based composite according to claim 12, wherein the content of the other additive is 0.01 mol% or more and 1 mol% or less with respect to 1 mol of the magnesium oxide in the final magnesium oxide-based composite.

14. The method for producing a magnesium oxide-based composite according to claim 12, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The total content of the ytterbium oxide and the other additives is 0.01 mol% or more and 10 mol% or less relative to 1 mol of magnesium oxide in the final magnesium oxide-based composite.

15. The method of producing a magnesium oxide-based composite according to claim 9, wherein, Also included are: (A1) a step of dispersing the sintering mixture in a water-soluble solvent.

16. The method for producing a magnesium oxide-based composite according to claim 9, wherein The granulation is granulation of the sintering mixture by a spray drying method.

17. An organic-inorganic composite formed by dispersing particles of the magnesium oxide-based composite according to claim 1 in a polymer matrix.

18. The organic-inorganic composite according to claim 17, wherein The polymer matrix is formed from at least one resin selected from the group consisting of a silicon-based resin, a polyurethane-based resin, an epoxy-based resin, and a thermoplastic resin.

Images