WO2010023971A1 - Oxyde et procédé pour contrôler les caractéristiques électriques d’un conducteur électrique - Google Patents

Oxyde et procédé pour contrôler les caractéristiques électriques d’un conducteur électrique Download PDF

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WO2010023971A1
WO2010023971A1 PCT/JP2009/053289 JP2009053289W WO2010023971A1 WO 2010023971 A1 WO2010023971 A1 WO 2010023971A1 JP 2009053289 W JP2009053289 W JP 2009053289W WO 2010023971 A1 WO2010023971 A1 WO 2010023971A1
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oxide
group
element selected
positive
raw material
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直 池田
徳亮 花咲
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国立大学法人岡山大学
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Definitions

  • the present invention relates to an oxide capable of controlling electrical properties of an electrical conductor and a method for controlling electrical properties of the electrical conductor.
  • the band gap of the electrical conductor is usually determined by the crystal structure that constitutes the conduction band and the forbidden band. For this reason, it is difficult to change the size of the band gap. Further, since the semiconductor material is a material having a specific band gap, such as Si or a compound semiconductor, the response by light absorption can respond only to a specific wavelength. Furthermore, it is impossible to control a wide band gap by doping.
  • compound semiconductors such as ZnSe and CdS, which are unstable or toxic substances, are used particularly in the wavelength band of the infrared region where energy is low, but the manufacturing method is difficult and there is a problem of toxicity. There is a problem that usage is restricted. Accordingly, there is a need for materials that can easily control electrical characteristics.
  • Non-Patent Document 1 reports the dielectric properties of LuFe 2 O 4 which is a two-dimensional triangular lattice iron double-charged oxide.
  • LuFe 2 O 4 is ferroelectric, and its manifestation principle is thought to be due to the action mechanism such as charge order formation by frustrated electron correlation, for example, the polar electron configuration on Fe 3+ , and known dielectrics And reported that it is different.
  • Non-Patent Document 2 the recent first calculation principle regarding LuFe 2 O 4 points out the existence of metallic conductive characteristics. It has been reported that the electrical conductivity up to now has a semiconductor behavior. N. Ikeda, et al. Nature 436 (2005) 1136. Xiang HJ, Whangbo MH, Phys. Rev. Lett. 98 (2007) 246403.
  • An object of the present invention is to provide an oxide capable of controlling an electric characteristic (semiconductor characteristic) such as a band gap to an arbitrary value and a method for controlling an electric characteristic to an arbitrary value.
  • the oxide according to the present invention is an oxide represented by the following formula (1), in which a part of R in the formula (1) is substituted with a solid divalent or lower element.
  • R is at least one element selected from the group consisting of Y, Dy, Lu, Er, Yb, Tm, Ho, Sc and In
  • M is Mn, Fe, Co and It is at least one element selected from the group consisting of Ga
  • m is 1 or 2
  • n is an integer of 0 or more.
  • M in formula (1) is preferably Fe.
  • the element of less than positive divalent is at least one element selected from the group consisting of Ca, Sr, Ba and Zn. Further, it is particularly preferable that the element having a positive divalent value or less is Ca.
  • the electric conductor according to the present invention is an electric conductor made of the above oxide.
  • the p-type semiconductor according to the present invention is a p-type semiconductor made of the above oxide.
  • the oxide according to the present invention is an oxide represented by the following formula (1), in which a part of R in the formula (1) is replaced by a solid solution with an element having a positive tetravalence or higher.
  • R is at least one element selected from the group consisting of Y, Dy, Lu, Er, Yb, Tm, Ho, Sc and In
  • M is Mn, Fe, Co and It is at least one element selected from the group consisting of Ga
  • m is 1 or 2
  • n is an integer of 0 or more.
  • M in formula (1) is preferably Fe.
  • the element more than the positive tetravalent is at least one element selected from the group consisting of Ce, Ti, Zr, Hf, Sn, Ta, Sb and Re.
  • the element more than the positive tetravalent is Ce.
  • the electric conductor according to the present invention is an electric conductor made of the above oxide.
  • An n-type semiconductor according to the present invention is an n-type semiconductor made of the above oxide.
  • the method for producing an oxide according to the present invention includes at least one of an oxide and carbonate of at least one element selected from the group consisting of Ca, Sr, Ba, and Zn, Y, Dy, Lu, Er, Yb, At least one oxide or carbonate of at least one element selected from the group consisting of Tm, Ho, Sc and In, and at least one element selected from the group consisting of Mn, Fe, Co and Ga.
  • the raw material powder is fired at 1000 ° C. to 1400 ° C. for 1 to 100 hours in an atmosphere having an oxygen partial pressure of 10 ⁇ 7 to 10 ⁇ 8 atm, It is preferable to perform rapid cooling in a temperature range of 40 ° C.
  • the method for producing an oxide according to the present invention includes at least one of an oxide and carbonate of at least one element selected from the group consisting of Ce, Ti, Zr, Hf, Sn, Ta, Sb and Re, A group consisting of Mn, Fe, Co and Ga, and at least one of an oxide and carbonate of at least one element selected from the group consisting of Y, Dy, Lu, Er, Yb, Tm, Ho, Sc and
  • a step of cooling after baking under heating is performed by mixing at least one of oxides and carbonates of at least one element selected from the above, and an atmosphere having an oxygen partial pressure of 10 ⁇ 6 to 10 ⁇ 11 atm.
  • the raw material powder is fired at 1000 ° C. to 1400 ° C. for 1 to 100 hours in an atmosphere having an oxygen partial pressure of 10 ⁇ 7 to 10 ⁇ 8 atm, It is preferable to perform rapid cooling in a temperature range of 40 ° C.
  • the method for controlling electrical characteristics according to the present invention is a method in which a part of R of the oxide represented by the following formula (1) is substituted by a solid solution substitution of an element less than positive divalent or an element greater than positive tetravalent.
  • This is a method for controlling the electrical characteristics of an object.
  • R is at least one element selected from the group consisting of Y, Dy, Lu, Er, Yb, Tm, Ho, Sc and In
  • M is Mn, Fe, Co and It is at least one element selected from the group consisting of Ga
  • m is 1 or 2
  • n is an integer of 0 or more.
  • control the band gap of the oxide by adjusting the amount of solid solution substitution of an element less than positive divalent or an element more than positive tetravalent.
  • the present invention it is possible to provide a method for controlling the electrical characteristics of an oxide to an arbitrary value. Further, it is possible to provide an oxide which is a non-toxic material and can control the band gap from the far infrared region to the visible light region.
  • FIG. 1 is a flowchart showing a method for controlling electrical properties of an electrical conductor according to the present invention.
  • FIG. 2 is an X-ray powder diffraction spectrum of the oxide produced in Example 6.
  • FIG. 3 is a diagram illustrating an example in which a change in dielectric constant with temperature is measured.
  • FIG. 4 is a diagram in which the reciprocal of the inflection point Tr is plotted on the horizontal axis and the measurement frequency is plotted on the vertical axis.
  • FIG. 5 is a diagram showing the band gap Q and the electrical conductivity ⁇ of the oxides obtained in the examples and comparative examples.
  • the oxide of the present invention is represented by the following formula (1), and a part of R in the formula (1) is solid solution substituted by an element having a positive divalent value or less, or an element having a positive tetravalent value or more.
  • R is at least one element selected from the group consisting of Y, Dy, Lu, Er, Yb, Tm, Ho, Sc and In, and M is Mn, Fe, Co , Ni, Cu, Zn, Al, Mg, and Ga, m is 1 or 2, and n is an integer of 0 or more.
  • the present inventors adjust the band gap because the band gap of the oxide represented by the formula (1) is dominated by the competition of the number of charges between elements less than positive divalent or more than positive tetravalent. I found out that I can do it.
  • the band gap of an electric conductor is determined by the crystal structure constituting the conduction band and the forbidden band, it has been difficult to change the size of the band gap.
  • Coulomb force such as an oxide represented by the formula (1)
  • the amount of elements less than positive divalent or the amount of elements greater than positive tetravalent is adjusted.
  • the oxide of the present invention has extremely low toxicity.
  • R in the formula (1) is at least one element selected from the group consisting of Y, Dy, Lu, Er, Yb, Tm, Ho, Sc and In.
  • Y, Lu and Yb are preferred.
  • Y or Yb is more suitable in the synthesis by firing.
  • M is at least one element selected from the group consisting of Mn, Fe, Co, and Ga. Fe and Mn are preferred. Fe is more preferable in terms of ease of control of the valence.
  • m is 1 or 2.
  • n is an integer of 0 or more, preferably an integer of 0 to 10, particularly preferably an integer of 0 to 6.
  • a part of R in the formula (1) is replaced by a solid solution with an element having a positive divalent value or less or an element having a positive tetravalent value or more.
  • an element having a positive divalent value or less for the oxide electrical characteristics can be controlled from conductivity to p-type semiconductor properties, and an electrical conductor and p-type semiconductor can be realized.
  • an element having a positive tetravalent or higher value for the oxide the electrical characteristics can be controlled from conductivity to n-type semiconductor properties, and an electrical conductor and an n-type semiconductor can be realized.
  • Examples of the positive divalent or lower element include at least one element selected from the group consisting of Mg, Ca, Sr, Ba, Na, K, Rb, Cs, and Zn. Moreover, this element less than positive divalent is preferably at least one element selected from the group consisting of Ca, Sr, Ba and Zn. Furthermore, Ca is more preferable in terms of ease of synthesis.
  • Examples of the positive tetravalent or higher element include at least one element selected from the group consisting of Ce, Ti, Zr, Hf, Sn, Ta, Sb, and Re. Moreover, this element more than the positive tetravalent is preferably at least one element selected from the group consisting of Ce, Ti, Zr and Sn. Furthermore, Ce is more preferable in terms of ease of synthesis.
  • substitution ratio X (R 1 ⁇ x A x : atomic ratio) of R with respect to an element having a positive divalent or lower element or a positive tetravalent or higher element (A) may be appropriately adjusted so as to obtain desired electrical characteristics.
  • This substitution rate is usually greater than 0 and 0.3 or less, preferably 0.01 to 0.2, more preferably 0.01 to 0.10.
  • the substitution ratio of R with respect to an element having a positive divalent value or less or an element having a positive tetravalent value or more can be adjusted by, for example, the charge ratio of raw materials when an oxide is synthesized.
  • the oxide of the present invention can be obtained, for example, by firing a mixture of raw materials.
  • oxide raw materials include oxides, sulfides, sulfates, halides (chlorides, bromides, etc.) containing R or M in formula (1), elements less than positive divalent or elements more than positive tetravalent. And carbonates. It is preferable to use oxides or carbonates of the above elements so that they are completely thermally decomposed at a low temperature so that no impurities remain.
  • the starting material is preferably sufficiently dried in advance.
  • At least one of an oxide and carbonate of at least one element selected from the group consisting of Ce, Ti, Zr, Hf, Sn, Ta, Sb and Re, and Y, Dy, Lu At least one selected from the group consisting of oxides and carbonates of at least one element selected from the group consisting of Er, Yb, Tm, Ho, Sc and In, and at least one selected from the group consisting of Mn, Fe, Co and Ga It is preferable to use a raw material powder in which at least one of an oxide of a seed element and a carbonate is mixed.
  • the raw materials can be mixed by, for example, a physical mixing method.
  • a specific physical mixing method is not particularly limited, and a known device such as a ball mill can be used.
  • the oxide of the present invention is obtained by firing the raw material powder of the obtained raw material mixture under heating in an ultra-low oxygen partial pressure atmosphere and then cooling it.
  • the raw material mixture may be uniaxially pressed into a form that is easy to handle before firing, for example, a pellet, and further molded by cold isostatic pressure (CIP) or the like. Moreover, you may calcine.
  • the firing conditions may be appropriately adjusted depending on the raw materials used.
  • the firing temperature is usually preferably 1000 ° C. to 1400 ° C., particularly preferably 1100 ° C. to 1300 ° C.
  • the firing time is preferably 1 hour to 100 hours, particularly preferably 5 hours to 72 hours.
  • the atmosphere of firing very low oxygen partial pressure atmosphere, it is preferable to adjust and more specifically an oxygen partial pressure of 10 -6 to 10 -11 atm, further the oxygen partial pressure of 10 -7 to 10 - It is particularly preferable to adjust to 8 atmospheres.
  • the obtained oxide is usually cooled in a temperature range of 15 to 40 ° C., and particularly rapidly cooled, so that the change in crystal structure can be suppressed, which is preferable.
  • the temperature lowering rate is preferably about 100 ° C./min to 1000 ° C./min.
  • An oxide single crystal may be produced from the obtained oxide sintered body.
  • a method for producing a single crystal can be produced by the following method, but is not necessarily limited to the following.
  • Examples of the method for producing the oxide single crystal include an optical FZ (floating zone: floating zone melting) method. Specifically, an oxide single crystal is grown using an infrared condensing heating furnace. The oxide sintered body is used as a raw material rod, and is placed on the upper axis of an infrared condensing heating furnace, and the oxide single crystal produced by another method as a seed crystal is placed on the lower axis. As the seed crystal, a single crystal portion obtained by preliminarily subjecting the oxide polycrystal to light heating zone melting is used.
  • optical FZ floating zone: floating zone melting
  • the tips of the raw material rod and seed crystal are moved so as to be in the center of the furnace and brought into contact with melting, while the raw material rod and seed crystal are rotated in opposite directions to adjust the crystal growth rate. A single crystal is grown.
  • the crystal growth atmosphere is an ultra-low oxygen partial pressure atmosphere.
  • the oxygen partial pressure is preferably adjusted to 10 ⁇ 6 to 10 ⁇ 11 atm, and the oxygen partial pressure is adjusted to 10 ⁇ 7 to 10 ⁇ 8 atm. It is particularly preferable to do this.
  • the obtained oxide is cooled, particularly rapidly cooled after firing.
  • the temperature lowering rate is preferably about 100 ° C./min to 1000 ° C./min.
  • the electrical properties of the oxide can be controlled by solid solution substitution of a part of R in the formula (1) with an element less than positive divalent or an element more than positive tetravalent.
  • FIG. 1 is a flowchart showing a method for controlling electrical properties of an electrical conductor according to an embodiment.
  • the amount of the positive divalent or lower element or the positive tetravalent or higher element contained in the oxide of the formula (1) is adjusted (step S1).
  • the electrical conductivity depending on the band gap of the oxide is changed and controlled (step S2).
  • the semiconductor property (electric property) of the oxide can be controlled to an arbitrary value by controlling the substitution rate of R with respect to an element having a positive or lower valence or an element having a positive or lower valence.
  • the band gap can be controlled from the far infrared region to the visible light region (0.1 eV to 2.5 eV).
  • the band gap is determined by the crystal structure, it is difficult to change the band cap.
  • a conventional semiconductor material is a material having a specific band cap, the optical response can respond only to a specific wavelength, and it is difficult to control the band gap in a wide range by doping. Therefore, a material capable of easily controlling the electrical characteristics has been demanded.
  • the electrical characteristics of the oxide can be controlled from conductivity to p-type semiconductivity. It has been found that the electrical properties of the oxide can be controlled from conductivity to n-type semiconductor properties by substitution, and the present invention has been achieved.
  • R is required to be 3+ as derived from the chemical formula RFe 2 O 4 . Therefore, from these conditions, the valence of R is 3+ in order to develop the characteristics of the substance of the present invention.
  • the present invention breaks down the first condition described above by substituting a small amount of divalent or tetravalent ions for R 3+ ions, and has physical properties such as optical properties, magnetic properties, electrical conductivity properties, and band gaps. It is based on finding that it changes markedly. Moreover, since the above-described crystal structure of RFe 2 O 4 is established, R ions known so far are Y, Dy, Lu, Er, Yb, Tm, Ho, Sc, and In. This is presumed to be restricted by the third condition described above.
  • the present invention does not exclude introducing a plurality of 3+ ions into R ions instead of one kind. It is speculated that dissolving ions with different ionic radii may further change the physical properties.
  • the essence of the present invention is based on the speculation that the first condition described above is modulated to adjust the charge frustration, and as a result, the physical properties including the band gap are changed. Moreover, in the example specifically described below as an example of the present invention, a small amount of Ca 2+ and Ce 4+ is substituted according to this idea, and the effect is confirmed.
  • Example 1 [Production of oxide] Iron oxide powder having a purity of 99.99% (Fe 2 O 3 manufactured by Kojundo Chemical Laboratory Co., Ltd.), ytterbium oxide powder having a purity of 99.99% (Yb 2 O 3 manufactured by Kojundo Chemical Laboratory Co., Ltd.) and purity 99 99% calcium carbonate (CaCO 2 manufactured by Kojundo Chemical Laboratory Co., Ltd.) is used.
  • Fe 2 O 3 is prepared by baking at 600 ° C. for 12 hours in oxygen.
  • Yb 2 O 3 is prepared by decarboxylation at 1000 ° C. in the atmosphere. The raw materials were weighed so that the atomic ratio (Yb: Ca: Fe) was 0.99: 0.01: 2, and pulverized and mixed to obtain a powder material.
  • This powder material was put into a press mold having a diameter of 10 mm, and was press-molded at a hydrostatic pressure of 60 MPa for 3 minutes and solidified into a cylindrical shape using a press machine. Next, the solidified powder material is taken out and used as a raw material body.
  • the heat treatment temperature was 1200 ° C., and the heat treatment time was 24 hours. After the heat treatment, the sample was taken out and rapidly cooled to room temperature (25 ° C.) to produce the oxide of the present invention.
  • the oxide obtained above was evaluated by ICP emission spectroscopy by quantitative analysis of composition analysis, and the atomic ratio (Yb: Ca: Fe) was 0.99: 0.01: 2.00. It was.
  • Example 4-6 An oxide was produced in the same manner as in Example 1 except that cerium oxide (manufactured by Kojundo Chemical Laboratory Co., Ltd.) was used instead of calcium carbonate as a raw material, and the raw material charge ratio was changed as follows. did.
  • Example 2-6 the composition and substitution of the obtained oxide were measured in the same manner as in Example 1, and it was confirmed that the composition was the same as the raw material charge ratio.
  • FIG. 2 shows an X-ray powder diffraction spectrum of the oxide produced in Example 6. As a result of analysis of peak shift by X-ray diffraction, it was confirmed that this oxide is a single phase of a crystal represented by YbFe 2 O 4 , and Yb was solid-substituted by Ce.
  • the temperature dependence of the dielectric constant of this measurement sample was measured, and the band gap was calculated from the dielectric dispersion of the measurement sample.
  • the dielectric constant was measured according to the method described in JP-A-2007-223886.
  • FIG. 3 shows an example in which the temperature change of the dielectric constant of the sample is measured. From the obtained result, the inflection point Tr of each frequency is determined.
  • f is a frequency
  • f 0 is a constant
  • k is a Boltzmann constant
  • T is an absolute temperature.
  • FIG. 5 is a graph showing the band gap Q and the electrical conductivity ⁇ of the oxides obtained in the above-described examples and comparative examples.
  • the electrical conductivity is a value estimated from an electrical resistance near room temperature.
  • Curve C1 shows the relationship between the band gap Q and the amount X of elements less than positive divalent or more than tetravalent
  • curve C2 shows the relationship between resistivity ⁇ and X at room temperature.
  • the absorption edge is in the vicinity of 1 eV. Therefore, even when irradiated with light of energy smaller than this (for example, light of 0.3 eV (wavelength 4 ⁇ m)), light absorption is achieved. Does not happen. This indicates that there is no light absorption even when irradiated with light having energy smaller than the band gap of Si.
  • the oxide of the present invention can realize optimum characteristics necessary for design in current control elements, voltage signal storage elements, dielectric elements, light sensing elements, solar cells, and the like.

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  • Organic Chemistry (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Metallurgy (AREA)
  • Structural Engineering (AREA)
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  • Compounds Of Iron (AREA)
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Abstract

La présente invention concerne un oxyde représenté par la formule (1), une partie de R dans la formule (1) ayant été soumise à une substitution en solution solide par un élément positif divalent ou inférieur ou un élément positif tétravalent ou supérieur. (RM2O4)m(RMO3)n  (1) dans laquelle R représente au moins un élément choisi dans le groupe constitué de Y, Dy, Lu, Er, Yb, Tm, Ho, Sc, et In; M représente au moins un élément choisi dans le groupe constitué de Mn, Fe, Co, et Ga; m est 1 ou 2; et n est un entier de 0 ou plus.
PCT/JP2009/053289 2008-08-29 2009-02-24 Oxyde et procédé pour contrôler les caractéristiques électriques d’un conducteur électrique WO2010023971A1 (fr)

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CN110137346B (zh) * 2019-06-18 2023-04-18 西安工业大学 一种锰掺杂铁酸钬HoMnxFe1-xO3磁电材料的制备方法

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