Nanoheterostructure and method for producing the same

Abstract

A nanoheterostructure includes a first inorganic component and a second inorganic component one of which is a matrix, and the other of which is three-dimensionally and periodically arranged in the matrix, and has a three-dimensional periodic structure whose average value of one unit length of a repeated structure is 1 nm to 100 nm.

Claims

1. A method for producing a nanoheterostructure, comprising: a first step of preparing a raw material solution by dissolving, in a solvent, a block copolymer comprising at least a first polymer block component and a second polymer block component which are immiscible but linked to each other, a first inorganic precursor having a solubility parameter different from that of the first polymer block component by 2 (cal/cm.sup.3).sup.1/2 or less, and a second inorganic precursor having a solubility parameter different from that of the second polymer block component by 2 (cal/cm.sup.3).sup.1/2 or less; and a second step including a phase-separation treatment for forming a nanophase-separated structure in which at least a first polymer phase comprising the first polymer block component with the first inorganic precursor introduced thereinto and a second polymer phase comprising the second polymer block component with the second inorganic precursor introduced thereinto are regularly arranged by self-assembly, a conversion treatment for converting the first inorganic precursor and the second inorganic precursor to a first inorganic component and a second inorganic component, respectively, and a removal treatment for removing the block copolymer from the nanophase-separated structure, to thereby obtain a nanoheterostructure comprising the first inorganic component and the second inorganic component, said second step including a step of carrying out a heat treatment on the raw material solution in an inert gas atmosphere as the phase-separation treatment, the conversion treatment and the removal treatment.

2. The method for producing a nanoheterostructure according to claim 1, wherein a solubility parameter difference between the first polymer block component and the first inorganic precursor is smaller than a solubility parameter difference between the first polymer block component and the second inorganic precursor.

3. The method for producing a nanoheterostructure according to claim 1, wherein a solubility parameter difference between the first polymer block component and the first inorganic precursor is smaller than a solubility parameter difference between the first polymer block component and the second inorganic precursor, and a solubility parameter difference between the second polymer block component and the second inorganic precursor is smaller than a solubility parameter difference between the second polymer block component and the first inorganic precursor.

4. The method for producing a nanoheterostructure according to claim 1, wherein the solubility parameter difference between the first polymer block component and the second inorganic precursor is more than 2 (cal/cm.sup.3).sup.1/2 .

5. The method for producing a nanoheterostructure according to claim 1, wherein the first inorganic precursor has a solubility parameter different from that of the second polymer block component by more than 2 (cal/cm.sup.3).sup.1/2, and the second inorganic precursor has a solubility parameter different from that of the first polymer block component by more than 2 (cal/cm.sup.3).sup.1/2.

6. The method for producing a nanoheterostructure according to claim 1, wherein at least one of the first inorganic precursor and the second inorganic precursor has a solubility parameter different from that of the solvent by 2 (cal/cm.sup.3).sup.1/2 or less.

7. The method for producing a nanoheterostructure according to claim 1, further comprising, after the heat treatment in the inert gas atmosphere, any one of: an oxidization treatment for oxidizing the first inorganic component and the second inorganic component in an oxidizing gas atmosphere; and a reduction treatment for reducing the first inorganic component and the second inorganic component in a reducing gas atmosphere.

8. A method for producing a nanoheterostructure comprising: a first step of preparing a raw material solution by dissolving, in a solvent, a block copolymer comprising at least a first polymer block component and a second polymer block component which are immiscible but linked to each other, a first inorganic precursor having a solubility parameter different from that of the first polymer block component by 2 (cal/cm.sup.3).sup.1/2 or less, and a second inorganic precursor having a solubility parameter different from that of the second polymer block component by 2 (cal/cm.sup.3).sup.1/2 or less; and a second step including a phase-separation treatment for forming a nanophase-separated structure in which at least a first polymer phase comprising the first polymer block component with the first inorganic precursor introduced thereinto and a second polymer phase comprising the second polymer block component with the second inorganic precursor introduced thereinto are regularly arranged by self-assembly, a conversion treatment for converting the first inorganic precursor and the second inorganic precursor to a first inorganic component and a second inorganic component, respectively, and a removal treatment for removing the block copolymer from the nanophase-separated structure, to thereby obtain a nanoheterostructure comprising the first inorganic component and the second inorganic component, said nanoheterostructure comprising the first inorganic component and the second inorganic component one of which is a matrix, and the other of which is three-dimensionally and periodically arranged in the matrix, and said nanoheterostructure having a three-dimensional periodic structure whose average value of one unit length of a repeated structure is 1 nm to 100 nm.

9. The method for producing a nanoheterostructure according to claim 8, wherein the inorganic component three-dimensionally and periodically arranged in the matrix has a shape selected from the group consisting of a spherical shape, a columnar shape, and a gyroid shape.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows schematic views illustrating nanophase-separated structures generated from A-B type block copolymers.

(2) FIG. 2 is a transmission electron microphotograph of a nanoheterostructure obtained in Example 1.

(3) FIG. 3 is a transmission electron microphotograph of a nanoheterostructure obtained in Example 2.

(4) FIG. 4 is a graph showing a small-angle X-ray diffraction pattern of a nanoheterostructure obtained in Example 3.

DESCRIPTION OF EMBODIMENTS

(5) Hereinafter, the present invention will be described in detail on the basis of preferred embodiments thereof. First, a method for producing a nanoheterostructure of the present invention will be described.

(6) The method for producing a nanoheterostructure of the present invention is a method comprising: a first step of preparing a raw material solution by dissolving, in a solvent, a block copolymer comprising at least a first polymer block component and a second polymer block component which are immiscible but linked to each other, a first inorganic precursor having a solubility parameter different from that of the first polymer block component by 2 (cal/cm.sup.3).sup.1/2 or less, and a second inorganic precursor having a solubility parameter different from that of the second polymer block component by 2 (cal/cm.sup.3).sup.1/2 or less; and a second step including a phase-separation treatment for forming a nanophase-separated structure in which at least a first polymer phase comprising the first polymer block component with the first inorganic precursor introduced thereinto and a second polymer phase comprising the second polymer block component with the second inorganic precursor introduced thereinto are regularly arranged by self-assembly, a conversion treatment for converting the first inorganic precursor and the second inorganic precursor to a first inorganic component and a second inorganic component, respectively, and a removal treatment for removing the block copolymer from the nanophase-separated structure, to thereby obtain a nanoheterostructure comprising the first inorganic component and the second inorganic component. Hereinafter, each step will be described.

(7) [First Step: Raw Material Solution Preparation Step]

(8) This step is a step of preparing a raw material solution by dissolving, in a solvent, a block copolymer to be described below and inorganic precursors to be described below.

(9) The block copolymer used in the present invention comprises at least a first polymer block component and a second polymer block component which are linked to each other. Specific examples of such a block copolymer include A-B type and A-B-A type block copolymers having a structure such as -(aa . . . aa)-(bb . . . bb)- in which a polymer block component A (first polymer block component) having a repeating unit a and a polymer block component B (second polymer block component) having a repeating unit b are linked end to end. Moreover, the block copolymer may be of a star type in which at least one polymer block component extends radially from a center, or of a type in which another polymer component is branched from the main chain of the block copolymer.

(10) The kind of the polymer block components constituting the block copolymer used in the present invention is not particularly limited, as long as the polymer block components are immiscible to each other. Thus, the block copolymer used in the present invention preferably comprises polymer block components having different polarities. Specific examples of such a block copolymer include polystyrene-poly(methyl methacrylate) (PS-b-PMMA), polystyrene-poly(ethylene oxide) (PS-b-PEO), polystyrene-polyvinylpyridine (PS-b-PVP), polystyrene-polyisoprene (PS-b-PI), polystyrene-polybutadiene (PS-b-PB), polystyrene-poly(ferrocenyldimethylsilane) (PS-b-PFS), poly(ethylene oxide)-polyisoprene (PEO-b-PI), poly(ethylene oxide)-polybutadiene (PEO-b-PB), poly(ethylene oxide)-poly(methyl methacrylate) (PEO-b-PMMA), poly(ethylene oxide)-poly(ethyl ethylene) (PEO-b-PEE), polybutadiene-polyvinylpyridine (PB-b-PVP), polyisoprene-poly(methyl methacrylate) (PI-b-PMMA), polystyrene-poly(acrylic acid) (PS-b-PAA), polybutadiene-poly(methyl methacrylate) (PB-b-PMMA), and the like. Above all, PS-b-PVP, PS-b-PEO, PS-b-PAA, and the like are preferable from the viewpoint that precursors are likely to be introduced into the respective polymer block components. This is because if the polymer block components greatly differ from each other in polarity, precursors which greatly differ from each other in polarity can also be used for the introduction.

(11) The molecular weight of the block copolymer and the polymer block components constituting the block copolymer can be selected as appropriate in accordance with the structure scale and arrangement of a nanoheterostructure to be produced. For example, it is preferably to use a block copolymer having a number average molecular weight of 100 to 10/000,000 (more preferably 1000 to 1,000,000). There is a tendency that the lower the number average molecular weight, the smaller the structure scale. Moreover, with regards to the number average molecular weight of the polymer block components, by adjusting the molecular weight ratio of each polymer block component, a nanophase-separated structure to be obtained by self-assembly in the subsequent nanophase-separated structure-forming step can have a desired structure. Accordingly, a nanoheterostructure having a structure in which inorganic components are arranged in a desired form can be obtained. It is also preferable to use a block copolymer which is easily decomposed by a heat treatment (calcination) or light irradiation to be described later, or a block copolymer which is easily removed with a solvent.

(12) In the present invention, a first inorganic precursor having a solubility parameter different from that of the first polymer block component by 2 (cal/cm.sup.3).sup.1/2 or less and a second inorganic precursor having a solubility parameter different from that of the second polymer block component by 2 (cal/cm.sup.3).sup.1/2 or less need to be used in combination. By using the first inorganic precursor and the second inorganic precursor satisfying such conditions in combination, a nanophase-separated structure is formed with achievement of self-assembly of the block copolymer in the step of forming the nanophase-separated structure described later, while the first inorganic precursor and the second inorganic precursor are sufficiently introduced into the first polymer block component and the second polymer block component, respectively. As the nanophase-separated structure is made to have a spherical structure, a columnar structure or a gyroid structure, the inorganic precursors having a three-dimensional nanoscale periodicity are arranged.

(13) A solubility parameter difference between the first polymer block component and the first inorganic precursor used in the present invention is preferably smaller than a solubility parameter difference between the first polymer block component and the second inorganic precursor. Moreover, a solubility parameter difference between the second polymer block component and the second inorganic precursor is preferably smaller than a solubility parameter difference between the second polymer block component and the first inorganic precursor. Further, it is more preferable that these two conditions be satisfied.

(14) Furthermore, the first inorganic precursor used in the present invention preferably has a solubility parameter different from that of the second polymer block component by more than 2 (cal/cm.sup.3).sup.1/2. Moreover, the second inorganic precursor preferably has a solubility parameter different from that of the first polymer block component by more than 2 (cal/cm.sup.3).sup.1/2. Further, it is more preferable that these two conditions be satisfied.

(15) By using the first inorganic precursor and the second inorganic precursor satisfying such conditions in combination, portions of the second inorganic precursor and the first inorganic precursor tend to be more surely prevented from being introduced as impurities into the first polymer block component and the second polymer block component, respectively, in the step of forming the nanophase-separated structure described later. Moreover, the purity of the inorganic component constituting a matrix in a nanoheterostructure to be obtained and/or the purity of the inorganic component arranged in the matrix tend to be more improved.

(16) In addition, preferably at least one (more preferably both) of the first inorganic precursor and the second inorganic precursor has a solubility parameter different from that of the solvent used by 2 (cal/cm.sup.3).sup.1/2 or less. By using the first inorganic precursor and/or the second inorganic precursor satisfying such a condition, the inorganic precursors tend to be more surely dissolved in the solvent, and the inorganic precursors tend to be more surely introduced into the polymer block components in the step of forming the nanophase-separated structure described later.

(17) Such inorganic precursors are preferably at least one selected from the group consisting of various salts (for example, carbonates, nitrates, phosphates, sulfates, chlorides, and the like of metals or metalloids), various alkoxides (for example, methoxides, ethoxides, propoxides, butoxides, and the like containing metals or metalloids), various complexes (for example, acetylacetonate complexes and the like of metals or metalloids), and various organometallic compounds (for example, phenyltrimethoxysilane, cobaltocene, and the like). These are selected and used as appropriate, in accordance with the combination of the inorganic components constituting the targeted nanoheterostructure and so as to satisfy the above-described conditions. The inorganic components after the conversion are each preferably at least one selected from the group consisting of oxides, metals, carbides, nitrides, borides and salts to be described later. From the viewpoint that it is possible to expect that various functions are demonstrated, the inorganic component preferably contains at least one element selected from the group consisting of iron (Fe), aluminium (Al), niobium (Nb), cobalt (Co), nickel (Ni), platinum (Pt), tellurium (Te), titanium (Ti) and silicon (Si). Accordingly, examples of the inorganic precursors suitably used in the present invention include: salts such as carbonates, nitrates, phosphates, sulfates, and chlorides containing the above element; alkoxides such as methoxides, ethoxides, propoxides, and butoxides containing the above element; complexes such as acetylacetonates including Fe(acac).sub.3, Co(acac).sub.3, Pt(acac).sub.2, and Ni(acac).sub.2; and organometallic compounds such as phenyltrimethoxysilane and cobaltocene.

(18) The solvent used in the present invention is not particularly limited, as long as the solvent is capable of dissolving the block copolymer and the first and second inorganic precursors to be used. Examples of the solvent include acetone, tetrahydrofuran (THF), toluene, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), chloroform, benzene, and the like. One kind of such solvents can be used alone, or a mixture of two or more kinds can be used.

(19) Note that, in the present description, to dissolve means a phenomenon that a substance (solute) is dissolved in a solvent to form a homogeneous mixture (solution), and includes cases where after dissolving, at least part of the solute becomes ions, where the solute is not dissociated into ions but exists in the form of molecule, where the solute exist as associating molecules and ions, and other cases.

(20) The ratios of the solutes (the block copolymer, the first inorganic precursor and the second inorganic precursor) in the obtained raw material solution are not particularly limited. When a total amount of the raw material solution is set to 100% by mass, the total of the solutes is preferably around 0.1 to 30% by mass, more preferably 0.5 to 10% by mass. Further, by adjusting amounts of the first and second inorganic precursors used relative to the block copolymer, the amount of each inorganic component to be introduced is adjusted, so that the ratio, size, and so on of each inorganic component in a nanoheterostructure to be obtained can be at desired levels.

(21) [Second Step: Nanoheterostructure-Forming Step]

(22) This step is a step including a phase-separation treatment, a conversion treatment, and a removal treatment, which are to be described in detail below, to thereby prepare a nanoheterostructure comprising the first inorganic component and the second inorganic component.

(23) First, the raw material solution prepared in the first step contains the block copolymer and the first and second inorganic precursors. In the present invention, the first inorganic precursor having a solubility parameter different from that of the first polymer block component constituting the block copolymer by 2 (cal/cm.sup.3).sup.1/2 or less is used in combination with the second inorganic precursor having a solubility parameter different from that of the second polymer block component by 2 (cal/cm.sup.3).sup.1/2 or less. Accordingly, the first inorganic precursor and the second inorganic precursor exist in such a state that the first and second inorganic precursors are sufficiently introduced into the first polymer block component and the second polymer block component, respectively. Hence, by the phase-separation treatment, a nanophase-separated structure is formed in which a first polymer phase comprising the first polymer block component with the first inorganic precursor introduced thereinto and a second polymer phase comprising the second polymer block component with the second inorganic precursor introduced thereinto are regularly arranged by self-assembly of the block copolymer. As the nanophase-separated structure is made to have a spherical structure, a columnar structure or a gyroid structure, the inorganic precursors having a three-dimensional nanoscale periodicity are arranged.

(24) Such a phase-separation treatment is not particularly limited. By carrying out a heat treatment at or above the glass transition temperature of the block copolymer used, self-assembly of the block copolymer is achieved, and the phase-separated structure is obtained.

(25) Next, in the present invention, the nanophase-separated structure formed by the phase-separation treatment is subjected to: the conversion treatment for converting the first inorganic precursor and the second inorganic precursor to a first inorganic component and a second inorganic component, respectively; and the removal treatment for removing the block copolymer from the nanophase-separated structure. As the inorganic precursors are converted to the respective inorganic components by such a conversion treatment and the block copolymer is removed by the removal treatment, the nanoheterostructure of the present invention is obtained in which an inorganic component having a three-dimensional specific nanoscale periodicity in such a shape as a spherical shape, a columnar shape, or a gyroid shape is arranged in the matrix made of another inorganic component, in accordance with the type of the nanophase-separated structure (spherical structure, columnar structure or gyroid structure).

(26) Such a conversion treatment may be: a step of heating at or above a temperature at which the inorganic precursors are converted to the inorganic components for conversion to the inorganic components; or a step of subjecting the inorganic precursors to hydrolysis and dehydration condensation for conversion to the inorganic components.

(27) Moreover, the removal treatment may be: a step of decomposing the block copolymer by a heat treatment (calcination) at or above a temperature at which the block copolymer is decomposed; a step of removing the block copolymer by dissolving the block copolymer in a solvent; or a step of decomposing the block copolymer by light irradiation such as ultraviolet irradiation.

(28) Further, in the second step of the present invention, if the raw material solution prepared in the first step is subjected to a heat treatment (calcination) at or above a temperature at which the block copolymer is decomposed, the phase-separation treatment, the conversion treatment and the removal treatment can be conducted all in one heat treatment. In order to complete the phase-separation treatment, the conversion treatment and the removal treatment by only one heat treatment in this manner, the heat treatment is carried out preferably at 300 to 1200 C. (more preferably 400 to 900 C.) for approximately 0.1 to 50 hours, although the conditions vary depending on the kind of the block copolymer and the inorganic precursors to be used.

(29) In addition, such a heat treatment is preferably carried out in an inert gas atmosphere (for example, in a nitrogen gas or the like). When the inorganic precursors are converted to the inorganic components and the block copolymer is removed in an inert gas atmosphere, the three-dimensional nanoscale periodic structure tends to be kept more surely. The condition of the heat treatment in such an inert gas atmosphere is not particularly limited. The treatment is preferably carried out at 300 to 1200 C. (more preferably 400 to 900 C.) for approximately 0.1 to 50 hours.

(30) Furthermore, after such a heat treatment in an inert gas atmosphere, it is possible to further carry out any one of: an oxidization treatment for oxidizing the first inorganic component and the second inorganic component in an oxidizing gas atmosphere (for example, in air or the like); and a reduction treatment for reducing the first inorganic component and the second inorganic component in a reducing gas atmosphere (for example, in hydrogen or the like). Note that the condition of the oxidization treatment in such an oxidizing gas atmosphere is not particularly limited. The treatment is preferably carried out at 300 to 1200 C. (more preferably 400 to 900 C.) for approximately 0.1 to 50 hours. In addition, the condition of the reduction treatment in the reducing gas atmosphere is not particularly limited, either. The treatment is preferably carried out at 300 to 1200 C. (more preferably 400 to 900 C.) for approximately 0.1 to 50 hours.

(31) Additionally, after the heat treatment or during the heat treatment, it is possible to further carry out a carbonization treatment on the inorganic components using an argon atmosphere or the like, a nitrogenization treatment on the inorganic components using an ammonia atmosphere or the like, a boronization treatment on the inorganic components using a boron carbide containing-atmosphere or the like, or other treatment by a known method for each treatment.

(32) Furthermore, the method for producing a nanoheterostructure of the present invention may further comprise, after the first step, a coating step of coating a surface of a substrate with the raw material solution. By performing the second step after the surface of the substrate is coated with the raw material solution, a coating film comprising the nanoheterostructure is formed on the surface of the substrate. The kind of the substrate to be used is not particularly limited, and can be selected as appropriate in accordance with the use or the like of the nanoheterostructure to be obtained. Moreover, as the coating method with the raw material solution, brush coating, spraying, dipping, spinning, curtain flow coating, or the like is used.

(33) Next, description will be given of a nanoheterostructure of the present invention that can be obtained by the method of the present invention.

(34) The nanoheterostructure of the present invention comprises a first inorganic component and a second inorganic component one of which is a matrix, and the other of which is three-dimensionally and periodically arranged in the matrix, wherein

(35) the nanoheterostructure has a three-dimensional periodic structure whose average value of one unit length of a repeated structure is 1 nm to 100 nm (more preferably 1 nm to 50 nm, particularly preferably 1 nm to 20 nm).

(36) Such a nanoheterostructure of the present invention has a structure that has not been formed by conventional production methods. It is possible to obtain nanoheterostructures in which the arrangement, composition, structure scale, and the like of various combinations of the multiple inorganic components are controlled in various ways. Therefore, the nanoheterostructure of the present invention demonstrates an interface increasing effect, a nanosize effect, and significant improvements in durability and the like when compared to conventional nanostructured materials, and as a result demonstrates a high magnetic force, a high relative permittivity, and so forth.

(37) Each of the first inorganic component and the second inorganic component constituting the nanoheterostructure of the present invention is preferably at least one component selected from the group consisting of metals, oxides, carbides, nitrides, borides, and salts, more preferably at least one component selected from the group consisting of metals and metal oxides.

(38) Such metals are not particularly limited. Examples thereof include various metals of transition elements and main group elements (such as alkali metals and alkaline earth metals), and metalloids (such as boron, silicon, germanium, arsenic, antimony, tellurium, and polonium). These metals may be alone, or may be a mixture or alloy of two or more kinds of these.

(39) Moreover, the oxides are not particularly limited, as long as the compounds contain oxygen and an element having a lower electronegativity than oxygen. Examples of the oxides include CeO.sub.2, RhO.sub.2, Rh.sub.2O.sub.3, RuO.sub.2, TiO.sub.2, SnO.sub.2, ZnO, Nb.sub.2O.sub.5, NbO.sub.2, InO.sub.3, ZrO.sub.2, La.sub.2O.sub.3, Ta.sub.2O.sub.5, WO.sub.3r Fe.sub.2O.sub.3, SiO.sub.2, NiO, Cu.sub.2O, Al.sub.2O.sub.3, SrTiO.sub.3, BaTiO.sub.3, CaTiO.sub.3, PbTiO.sub.3, BaZrO.sub.3, PbZrO.sub.3, CeZrO.sub.4, AFe.sub.2O.sub.4 (A is Mn, Co, Ni, Cu, Zn, or the like), and the like. These oxides may be alone, or may be a composite oxide of two or more kinds of these.

(40) Further, the carbides are not particularly limited. Examples thereof include silicon carbide, boron carbide, iron carbide, cobalt carbide, and the like. These carbides may be alone, or may be a mixture of two or more kinds of these.

(41) In addition, the nitrides are not particularly limited. Examples thereof include boron nitride, carbon nitride, silicon nitride, gallium nitride, indium nitride, aluminium nitride, tin nitride, titanium nitride, and the like. These nitrides may be alone, or may be a mixture of two or more kinds of these.

(42) Furthermore, the borides are not particularly limited, as long as the borides form transition metals (such as lanthanides and actinides). Examples of the borides include MgB.sub.2, OsB.sub.2, ReB.sub.2, Nd.sub.2Fe.sub.14B, NaB.sub.15, Mn.sub.4B, V.sub.3B, FeB, CoB, CrB.sub.2, and the like. These borides may be alone, or may be a mixture of two or more kinds of these.

(43) Additionally, the salts are not particularly limited, as long as the salts are compounds in which negative ions (anions) derived from an acid are ionically bonded to positive ions (cations) derived from a base. Examples of the salts include carbonates, sulfates, phosphates, chlorides, and the like. Specific examples include NH.sub.4Cl, CuSO.sub.4, NaHSO.sub.4, NaH.sub.2PO.sub.4, NaCl, CaCl.sub.2, CH.sub.3COONa, Na.sub.2CO.sub.3, NaHCO.sub.3, Na.sub.2HPO.sub.4, BaSO.sub.4, Ca.sub.3(OO.sub.4).sub.2, CaCl(OH), MgCl(OH), and the like. These salts may be alone, or may be a mixture of two or more kinds of these.

(44) When such a nanoheterostructure of the present invention is used as a composite magnetic material, each of the first inorganic component and the second inorganic component is preferably a magnetic material. In this case, it is more preferably one of the first inorganic component and the second inorganic component be a hard magnetic material (for example, FePt, SmCo.sub.5, Nd.sub.2Fe.sub.14B, or the like), and that the other be a soft magnetic material (for example, Fe, Co, a permalloy, a soft ferrite, or the like).

EXAMPLES

(45) Hereinafter, the present invention will be more specifically described based on Examples and Comparative Examples. However, the present invention is not limited to the following examples.

Example 1

(46) 0.1 g of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) as a block copolymer, 0.038 g of titanium chloride as a Ti precursor, and 0.032 g of tin iodide as a Sn precursor were dissolved in 10 mL of toluene, and thereby a raw material solution was obtained. Note that PS of PS-b-P4VP had a molecular weight of 2210.sup.3, and P4VP had a molecular weight of 2210.sup.3. In addition, the solubility parameter differences of each component from the Ti precursor and the Sn precursor were as shown in Table 2 below.

(47) TABLE-US-00002 TABLE 2 Solubility parameter difference [(cal/cm.sup.3).sup.1/2] PS P4VP toluene Ti precursor 2 or less more than 2 2 or less Sn precursor more than 2 2 or less more than 2

(48) Next, the obtained raw material solution was placed in a heat treatment container in such a manner that the thickness would be approximately 500 m after a heat treatment. The heat treatment was carried out in a nitrogen atmosphere at 850 C. for 6 hours, and further in a reducing atmosphere (Ar+4% H.sub.2) at 600 C. for 1 hour. Thus, an inorganic structure was obtained.

(49) The obtained inorganic structure was observed with a transmission electron microscope (TEM). As shown in FIG. 2, a nanoheterostructure was confirmed in which spherical Sn was three-dimensionally and periodically arranged in the Ti matrix.

(50) Further, the small-angle X-ray diffraction pattern of the obtained inorganic structure was measured with a small-angle X-ray diffraction measuring device (manufactured by Rigaku Corporation, product name: NANO-Viewer). The distance (d) of the periodic structure was approximately 13.9 nm, and a characteristic diffraction peak pattern in a spherical structure (i.e., the ratio of intensities of diffraction spectra (q) at the peak position) was confirmed.

Example 2

(51) The raw material solution obtained in the same manner as in Example 1 was placed in a heat treatment container in such a manner that the thickness would be approximately 500 m after a heat treatment. The heat treatment was carried out in a nitrogen atmosphere at 850 C. for 6 hours, and further in air at 600 C. for 1 hour. Thus, an inorganic structure was obtained.

(52) The obtained inorganic structure was observed with a transmission electron microscope (TEM) as in Example 1. As shown in FIG. 3, a nanoheterostructure was confirmed in which spherical SnO.sub.2 was three-dimensionally and periodically arranged in the TiO.sub.2 matrix.

(53) Further, the small-angle X-ray diffraction pattern of the obtained inorganic structure was measured as in Example 1. The distance (d) of the periodic structure was approximately 15.0 nm, and a characteristic diffraction peak pattern in a spherical structure (i.e., the ratio of intensities of diffraction spectra (q) at the peak position) was confirmed.

Comparative Example 1

(54) 0.1 g of poly(methyl methacrylate)-b-polyacrylonitrile (PMMA-b-PAN) as a block copolymer, 0.057 g of cobalt acetylacetonate as a Co precursor, and 0.030 g of titanium chloride as a Ti precursor were dissolved in 10 mL of toluene, and thereby a raw material solution was obtained. Note that PMMA of PMMA-b-PAN had a molecular weight of 2710.sup.3, and PAA has a molecular weight of 2410.sup.3. In addition, the solubility parameter differences of each component from the Co precursor and the Ti precursor were as shown in Table 3 below.

(55) TABLE-US-00003 TABLE 3 Solubility parameter difference [(cal/cm.sup.3).sup.1/2] PAN PMMA toluene Ti precursor more than 2 2 or less 2 or less Co precursor more than 2 2 or less 2 or less

(56) Next, the obtained raw material solution was subjected to the heat treatment as in Example 1. Thus, an inorganic structure was obtained. The obtained inorganic structure was observed with a transmission electron microscope (TEM) as in Example 1. It was confirmed that no periodic structure was formed. Further, the small-angle X-ray diffraction pattern of the obtained inorganic structure was measured as in Example 1. A characteristic diffraction peak pattern in a periodic structure (i.e., the ratio of intensities of diffraction spectra (q) at the peak position) was not confirmed.

Example 3

(57) 0.1 g of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) as a block copolymer, 0.071 g of Fe(acac).sub.3 as a FePt precursor (Fe precursor and Pt precursor) that was a hard magnetic material, 0.079 g of Pt(acac).sub.2, and 0.035 g of CoCL.sub.2(4Me-Py) (cobalt dichloride bis-4-methyl pyridine) as a Co precursor that was a soft magnetic material were dissolved in 10 mL of toluene, and thereby a raw material solution was obtained. Note that PS of PS-b-P4VP had a molecular weight of 2210.sup.3, and P4VP had a molecular weight of 2210.sup.3. In addition, the solubility parameter differences of each component from the FePt precursor (Fe precursor and Pt precursor) and the Co precursor were as shown in Table 4 below.

(58) TABLE-US-00004 TABLE 4 Solubility parameter difference [(cal/cm.sup.3).sup.1/2] PS P4VP toluene Fe precursor 2 or less more than 2 2 or less Pt precursor 2 or less more than 2 2 or less Co precursor 2 or less 2 or less 2 or less

(59) Next, the obtained raw material solution was subjected to the heat treatment as in Example 1. Thus, an inorganic structure was obtained. The obtained inorganic structure was observed with a transmission electron microscope (TEM) as in Example 1. A nanoheterostructure was confirmed in which columnar FePt was three-dimensionally and periodically arranged in the Co matrix.

(60) Further, the small-angle X-ray diffraction pattern of the obtained inorganic structure was measured as in Example 1. The distance (d) of the periodic structure was approximately 10 nm, and a characteristic diffraction peak pattern in a columnar structure (i.e., the ratio of intensities of diffraction spectra (q) at the peak position) was confirmed as shown in FIG. 4.

(61) Furthermore, the magnetization curve of the obtained inorganic structure was measured with a magnetization curve measuring device (manufactured by Toei Industry Co., Ltd., product name: Vibrating Sample Magnetometer). It was found out that the value of the maximum energy product of the obtained nanoheterostructure was 12% higher than that of an inorganic structure of a FePt single phase prepared for comparison.

Comparative Example 2

(62) According to the method described in NPL 1, a composite material was prepared using, as a starting material, nanoparticles whose particle diameter had been controlled. Specifically, 6.8 mmol of oleic acid, 6.8 mmol of oleylamine, and 0.43 mmol of Fe(acac).sub.3 were dissolved in 20 mL of a 1-octanol solution containing Pd nanoparticles (Pd=0.17 mmol) having an average particle diameter of 5 nm and then heated at 180 C. to synthesize Pd/-Fe.sub.2O.sub.3 nanoparticles having a -Fe.sub.2O.sub.3 phase anisotropically grown on the surface of the Pd nanoparticles. The resultant was subjected to a calcination treatment in a reducing atmosphere (Ar+4% H.sub.2). Thus, a composite material (FePd/Fe) was obtained.

(63) The obtained composite material was observed with a transmission electron microscope (TEM) as in Example 1. It was confirmed that the particle diameter of the FePd nanoparticles dispersed in the Fe matrix and the distance among the particles greatly varied, and that no periodic structure was formed. Further, the small-angle X-ray diffraction pattern of the obtained composite material was measured as in Example 1. A characteristic diffraction peak pattern in a periodic structure (i.e., the ratio of intensities of diffraction spectra (q) at the peak position) was not confirmed.

Comparative Example 3

(64) A composite material (FePt/Fe) was obtained in the same manner as in Comparative Example 2, except that Pt nanoparticles (Pt=0.17 mmol) having an average particle diameter of 8.2 nm were used in place of the Pd nanoparticles used in Comparative Example 2. The obtained composite material was observed with a transmission electron microscope (TEM) as in Example 1. It was confirmed that the particle diameter of the FePt nanoparticles dispersed in the Fe matrix and the distance among the particles greatly varied, and that no periodic structure was formed. Further, the small-angle X-ray diffraction pattern of the obtained composite material was measured as in Example 1. A characteristic diffraction peak pattern in a periodic structure (i.e., the ratio of intensities of diffraction spectra (q) at the peak position) was not confirmed.

(65) Further, the magnetization curve of the obtained composite material was measured as in Example 3. It was found out that the value of the maximum energy product of the obtained composite material was as low as 42% of that of an inorganic structure of a FePt single phase prepared for comparison.

Example 4

(66) The raw material solution obtained in the same manner as in Example 1 was placed in a heat treatment container in such a manner that the thickness would be approximately 500 m after a heat treatment. The heat treatment was carried out in an ammonia atmosphere at 550 C. for 6 hours. Thus, an inorganic structure was obtained.

(67) The obtained inorganic structure was observed with a transmission electron microscope (TEM) as in Example 1. A nanoheterostructure was confirmed in which spherical Sn nitride was three-dimensionally and periodically arranged in the Ti nitride matrix.

(68) Further, the small-angle X-ray diffraction pattern of the obtained inorganic structure was measured as in Example 1. The distance (d) of the periodic structure was approximately 18.2 nm, and a characteristic diffraction peak pattern in a spherical structure (i.e., the ratio of intensities of diffraction spectra (q) at the peak position) was confirmed.

Example 5

(69) 0.1 g of polystyrene-b-poly(4-vinylpyridine) (PS-b-P4VP) as a block copolymer, 0.071 g of Fe(acac).sub.3 as a Fe precursor that was a hard magnetic material, and 0.035 g of CoCl.sub.2(4Me-Py) (cobalt dichloride bis-4-methyl pyridine) as a Co precursor that was a soft magnetic material were dissolved in 10 mL of toluene, and thereby a raw material solution was obtained. Note that PS of PS-b-P4VP had a molecular weight of 2210.sup.3, and P4VP had a molecular weight of 2210.sup.3. Next, the obtained raw material solution was placed in a heat treatment container in such a manner that the thickness would be approximately 500 m after a heat treatment. The heat treatment was carried out in an argon atmosphere at 900 C. for 12 hours. Thus, an inorganic structure was obtained.

(70) The obtained inorganic structure was observed with a transmission electron microscope (TEM) as in Example 1. A nanoheterostructure was confirmed in which Fe carbide and Co carbide were alternately and periodically arranged and formed a multilayer structure.

(71) Further, the small-angle X-ray diffraction pattern of the obtained inorganic structure was measured as in Example 1. The distance (d) of the periodic structure was approximately 21.6 nm, and a characteristic diffraction peak pattern in a lamellar structure (i.e., the ratio of intensities of diffraction spectra (q) at the peak position) was confirmed.

Example 6

(72) The raw material solution obtained in the same manner as in Example 5 was placed in a heat treatment container in such a manner that the thickness would be approximately 500 m after a heat treatment. The heat treatment was carried out together with B.sub.4C in vacuum (10.sup.3 Torr) at 1150 C. for 6 hours. Thus, an inorganic structure was obtained.

(73) The obtained inorganic structure was observed with a transmission electron microscope (TEM) as in Example 1. A nanoheterostructure was confirmed in which Fe boride and Co boride were alternately and periodically arranged and formed a multilayer structure.

(74) Further, the small-angle X-ray diffraction pattern of the obtained inorganic structure was measured as in Example 1. The distance (d) of the periodic structure was approximately 17.4 nm, and a characteristic diffraction peak pattern in a lamellar structure (i.e., the ratio of intensities of diffraction spectra (q) at the peak position) was confirmed.

INDUSTRIAL APPLICABILITY

(75) As described above, the production method of the present invention makes it possible to obtain the nanoheterostructure of the present invention in which an inorganic component having a three-dimensional specific nanoscale periodicity in such a shape as a spherical shape, a columnar shape, or a gyroid shape is arranged in a matrix made of another inorganic component.

(76) Moreover, such a nanoheterostructure of the present invention has a structure that has not been formed by conventional production methods. It is possible to obtain nanoheterostructures in which the arrangement, composition, structure scale, and the like of various combinations of the multiple inorganic components are controlled in various ways.

(77) Therefore, the nanoheterostructure of the present invention demonstrates an interface increasing effect, a nanosize effect, and significant improvements in durability and the like when compared to conventional nanostructured materials, and as a result demonstrates a high magnetic force, a high relative permittivity, and so forth. Accordingly, the nanoheterostructure of the present invention is useful as functional materials such as piezoelectric materials, thermoelectric materials, secondary cells, fine ceramics, magnetic materials and optical devices.