JPH0963884A - Capacitor employing superdielectric - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a capacitor employing a superdielectric and having extremely high capacitance by employing a two layer structure of superdielectric layer and a normal dielectric layer. SOLUTION: The capacitor employing a superdielectric comprises a superdielectric layer 11, a normal dielectric layer 12 arranged in series with the superdielectric layer 11, an anode metal electrode 13 connected with the upper surface of superdielectric layer 11, and a cathode metal electrode 14 connected with the lower surface of normal dielectric layer 12, wherein a DC power supply 15 is connected between the electrode 13, 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery, and more particularly to a battery using a super dielectric.

[0002]

2. Description of the Related Art Conventionally, techniques in such a field include:
There was something like the following. FIG. 5 shows the relationship between the structure of a capacitor (capacitor) using an ordinary dielectric (dielectric constant ε ₁ , area S, thickness t ₁ ) and various electrostatic quantities. The electrostatic capacitance C ₀ [F] in this case is (when t ₁ is thin) C ₀ = Q / V = Sσ / t ₁ E = Sε ₁ E / t ₁ E = Sε
It is given by ₁ / t ₁ .

[0003]

However, the above-mentioned conventional capacitor has only a normal capacitance and is not technically satisfactory. The present invention
To solve the above problems, the super-dielectric layer and the ordinary dielectric layer
An object of the present invention is to provide a capacitor having a layered structure and using a super-dielectric having an extremely large capacitance.

[0004]

In order to achieve the above object, the present invention provides: (1) a capacitor using a super-dielectric, the super-dielectric layer being disposed in series with the super-dielectric layer. The conventional dielectric layer, the metal electrode connected to the super-dielectric layer, and the metal electrode connected to the normal dielectric layer are provided.

(2) In the capacitor using the super-dielectric according to the above (1), the super-dielectric layer is made of a lanthanum-based superconductor La _2-x Sr _x CuO ₄ crystal. It is the one. (3) In the capacitor using the superdielectric described in (2), the lanthanum-based superconductor La _2−x Sr _x CuO ₄ crystal has a carrier doping amount of x = 1/4 ⁿ or x = 2/4.
ⁿ (where n is a positive integer).

(4) In the capacitor using the super-dielectric according to the above (1), the super-dielectric layer is Cu which is a two-dimensional conductive layer.
The number of hole carriers per O ₂ unit is 1/4 ⁿ or 2 /
It is a two-dimensional conductive substance having holes or electrons equivalent to the carrier state of 4 ⁿ (where n is a positive integer) as carriers. (5) In the electric storage device using the superdielectric described in (1) above, the two-dimensional conductive material is an oxide.

Since the above-mentioned constitutions (1) to (5) are adopted, it is possible to obtain a condenser having an extremely large electrostatic capacity.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration diagram of a capacitor using a superconductor of the present invention, FIG. 2 is an explanatory diagram of polarization of a superconductor and a superconductor, and FIG. 2A is an explanatory diagram of polarization of a superconductor, FIG. 2 (b) is an explanatory diagram of polarization of a super-dielectric, FIG. 3 is a diagram showing a polarization state of a vacuum, an ordinary dielectric substance, and a super-dielectric, and FIG. 3 (a) is a diagram showing a polarization state in a vacuum. 3 (b) is a diagram showing the polarization state of a normal dielectric, and FIG. 3 (c) is a diagram showing the polarization state of a super-dielectric.

As shown in FIG. 1, the capacitor using the superdielectric of the present invention includes a superdielectric layer 11 and this superdielectric layer 11.
A normal dielectric layer 12 arranged in series with the anode metal electrode 13 connected to the upper surface of the super-dielectric layer 11 and a cathode metal electrode 14 connected to the lower surface of the normal dielectric layer 12. A DC power supply 15 is connected between the electrodes 13 and 14.

The anode metal electrode 1 shown in this embodiment is used.
Needless to say, even if 3 is replaced with the cathode metal electrode and the cathode metal electrode 14 is replaced with the anode metal electrode and a reverse voltage is applied, negative external charges are injected and the capacitance increases. First, the super-dielectric will be described here. [A] Electronic state of superconductor The electronic structure of a superconductor is relative to a superconductor. The electronic states of the superconductor are as follows.

(I) Charged particles (electrons, holes, etc.) that are responsible for conductivity form a pair in the momentum space and fill up in (around the origin of) the momentum space. (Ii) The phase Θ of all charged particle pairs is the same. This phase Θ becomes the phase of the order parameter. (Iii) The passage of the magnetic flux quantum causes a phase difference of 2π between the charged particle pairs on both sides of the passage locus. Corresponding to these, the electronic state of the super-dielectric is as follows.

(1) The charged particle system is on a stacked two-dimensional surface and forms a pair of charged particles on each two-dimensional (xy) surface,
It is full of two-dimensional surfaces. (2) For convenience, if the (xy) plane is taken on the two-dimensional plane and the z axis is taken perpendicularly to the plane, the phase of the charged particle pair is determined by the z coordinate. Therefore, all charged particle pairs on the same plane have the same phase Θ
It is in. This phase Θ becomes the phase of the order parameter.
In the equilibrium state, all the charged particle pairs on the stacked two-dimensional surface have the same phase.

(3) If a charge injected from the outside into the super-dielectric (hereinafter referred to as an external charge) passes through the charged particle pair at a certain position along the z axis, the phase of the charged particle pair before and after the passage. Changes by 2π. [B] Fabrication of Super Dielectric The fabrication of a super dielectric is easy if a high temperature oxide super conductor having a two-dimensional conductive surface (CuO ₂ surface) is used. For example, the most simple structure high temperature oxide superconductor La _2-x Sr _x Cu
In O ₄ , when Cu = 1/4 ⁿ (n = 1, 2, 3, ...), the hole pairs fill the CuO ₂ plane, so that the property of a super-dielectric appears. Other high-temperature oxide superconductors also become superdielectrics when the amount of carriers (electrons or holes) per atom collective element of CuO ₂ or the corresponding two-dimensional conductive surface is ¼ ⁿ .

[C] Polarization Characteristics Based on the relativity of electronic states, a superdielectric material exhibits electromagnetic characteristics relative to a superconductor. Corresponding to the perfect diamagnetism of superconductors, superconductors exhibit "perfect dielectricity" and the internal "electric flux density" becomes zero. Their characteristics are as shown in FIG. As shown in FIG. 2, in the same way as the super-dielectric has the property of keeping the phase of the order parameter Θ constant, the super-dielectric has the property of keeping the phase of the order parameter Θ constant inside. Yes, this results in zero net charge transfer inside. This property is “D = 0 inside”
Bring about the characteristics.

What kind of polarization occurs in the super dielectric will be described. FIG. 3 shows a comparison of the polarization states of vacuum, ordinary dielectric materials, and superdielectrics. As shown in FIG.
In the case of vacuum, polarization produces an electric flux density of D = ε ₀ E from the electric field E. However, ε ₀ is the dielectric constant of vacuum. In ordinary dielectric polarization, molecular polarization is added to vacuum polarization.
When the charge (external charge) Q _ex injected from the outside does not enter the inside (excluding the surface region) of the super-dielectric, "polarization" does not occur inside. It is the case where the external charge Q _ex penetrates inside that "polarization" occurs inside. This invasion of external charges occurs in the form of "charge quanta". The “charge quantum” is composed of an external charge and a “polarized charge” Q _po (= −Q _ex ) distributed around the external charge and shielding the electric flux of Q _ex .

This "polarization charge" is generated by the displacement of the charged particle pair system. In a super-dielectric which is full on two dimensions of a charged particle pair, the free movement of the charged particle pair on the plane is limited due to mutual strong Coulomb repulsion and quantum effects.
The displacement of the charged particle pair is limited to (i) when the entire system moves as a unit, and (ii) when a part of the system moves in the form of “polarization”.

The charge transfer in the direction along the z-axis will be considered below. When the electrostatic shield distance is sufficiently long, the force acting on each "charge quantum" is determined by the repulsive force of the external charges. The force acting on the external charge density per unit volume ρ _ex is f
= If ^{_{ρ ex E * ≡ρ ex D *}} / ε, f = -V (D * 2 / 2ε) = - (V · D *) D * / ε = ρ
_{From ex} E ^* , ρ _ex = −V · D ^* .

This relationship indicates that D ^* is the "polarization" vector given by the product of ρ _ex and its displacement vector. ε is the effective dielectric constant of the charged particle pair system. In the equilibrium state where there is no current, the force acting on the external charge Q _ex becomes zero. The force f is canceled by the field that forms the polarization of the charged particle pair system [that is, the shielding charge Q ^- _po and the electric field that maintains the polarization charge Q ⁺ _po (= -Q ^- _po ) existing on the system surface]. To be done. If this polarization vector is P ^* , the displacement vector of Q _ex , which is the displacement of “charge quantum”, and the displacement vector of Q ⁻ _po (= −Q _ex ) are the same, so P ^* = −D ^* The relationship will always be established. The electrostatic potential forming the polarization P ^* is also the chemical potential of the charged particle pair system.

A finite applied current (polarization vector D ^{* of the} external charge) that is small enough to be considered that the super-dielectric is close to the equilibrium state ^.
If the temporal monotonically increased) are present, the polarization vector of the charged particle pair system P ^* will also increase temporally monotonous. Therefore, when the “voltage terminal” exchanges charge with the charged particle pair in the four-terminal method measurement under this situation, the “electromotive force” opposite to the “voltage” determined by the flow of external charges and Ohm's law is applied. Will be detected. Also, as described below,
An increase in capacitance is observed in this "polarized state" in the composite capacitance of the dielectric and superdielectric.

[D] A storage battery using the superdielectric of the present invention will be described below. As described above, the gradient of the electric potential of the electron pair system when the external charge is injected into the superconductor has the opposite sign to the normal ohmic voltage determined by the current that is the flow of the external charge. Therefore, if only the super-dielectric is sandwiched by metal electrodes and the power supply is connected to this, assuming that the super-dielectric state is completely maintained, the resistance value will be negative and the thermodynamics of the circuit system including the power supply will be negative. The condition of is not satisfied.

In reality, in this situation, the superdielectric state is partially destroyed in the superdielectric state, and as a whole, the ideal state cannot be maintained. Then, a positive resistance current flows between the electrodes. The following two conditions are necessary in order to configure a capacitance that operates stably. (I) The current is zero in the steady state. (Ii) Assuming that the superdielectric is in the superdielectric state, the capacitance of the entire system has a positive value. In order to satisfy these two conditions, it is necessary to have a structure in which a double layer of a super dielectric layer and a normal dielectric layer is sandwiched.

Next, the electrostatic capacities of a capacitor using only a normal dielectric and a capacitor also using a super dielectric will be compared and described. A capacitor using a normal dielectric (dielectric constant ε ₁ , area S, thickness t ₁ ) has a configuration as shown in FIG. Next, as shown in FIG. 1, a double layer of an ordinary dielectric layer (dielectric constant ε ₁ , area S, thickness t ₁ ) 12 and a super-dielectric layer (area S, thickness t ₂ ) 11 is formed into a metal. Consider a capacitor sandwiched between electrodes. Inside the super-dielectric, D ₂ ^* + P ₂ ^* = 0 holds in equilibrium.

The electrostatic field E₂= -E₂ ^*= -D₂ ^*/
ε₂Occurs. ε₂Is the effective of the charged particle pair system of superdielectric
It is the dielectric constant. The boundary between the positive electrode and the super-dielectric is (effective
2) There is no barrier, and there is no charge like a normal electrode / dielectric boundary.
There is no charge accumulation, and the electrode charge is external charge inside the super dielectric.
Injected. Through the positive potential electrode of Fig.
The amount of charge injected per unit area is (polarization vector P
₂ ^*Polarization vector D regardless of the value of₂ ^*Equal to
Yes. Due to the continuity of the electric current, the unit surface that flows out through the negative electrode
The charge per product (equal to the charge stored on the negative electrode) is positive.
Equal to the charge flowing through the pole. Therefore, normal dielectric
Polarization vector equal to the amount of charge transfer per unit area on the body side
Le D₁Is the injection charge D₂ ^*Must be equal to. I
It is the continuity of "electric flux density".

As described above, in the steady state (where no current is present), the electric charge E ₂ that forms and maintains P ₂ ^* that cancels D ₂ ^* = σ exists inside. ^{_{E 2 = P 2 * / ε}} 2 = -D 2 * / ε 2 = -σ / ε 2 E 2 is directed to the opposite direction to the electric field generated when applying an external from the charge to the normal in the material. The existence of the "negative voltage" due to E ₂ and the consistency with the power supply voltage are as follows.
This is achieved by the presence of a voltage drop due to the resistance of the circuit or the “contact resistance” between the sample material and the metal terminal, but in the steady state where no current exists as shown in FIG. 1, the presence of a potential difference in the normal dielectric region. Achieved by

The capacitance C _S [F] of this composite capacitor
Is given by C _S = Q / V = _S σ / (t ₁ E ₁ + t ₂ E ₂ ) = S σ / [(t ₁ σ / ε ₁ ) + (− t ₂ σ / ε ₂ )] = S / [(t ₁ / ε ₁ ) − (t ₂ / ε ₂ )] This formula shows that when the film thickness t ₂ of the superdielectric layer is gradually increased, C _S → + ∞ in the limit of t ₂ → t ₁ ε ₂ / ε _1. Which means that an infinite capacitance can be obtained.

The experimental results of the capacitor using the superdielectric of the present invention will be described below. Thickness t ₁ of _{SrTiO 3 La 2-x Sr x} CuO 4 having a thickness t ₂ on the substrate (x = 1/1
6) Epitaxially grow a thin film,
The capacitance C _S [F] of the electric storage device sandwiched between the Pd electrodes was measured. _Let C _O [F] be the capacitance when t ₂ = 0, and C _S
/ C _O on the vertical axis and t ₂ / t ₁ (ε ₂ / ε ₁ ) on the horizontal axis, greenhouse 300 [K], liquid nitrogen temperature 77
FIG. 4 shows an example of measurement at [K] and a liquid helium temperature of 4.2 [K]. These results show that the above calculations are almost correct.

The value on the vertical axis when the horizontal axis was around 1 at room temperature decreased to about half or less of that at low temperature. This occurs because the critical temperature is near room temperature. In the future, it is necessary to develop a material that has a sufficiently high critical temperature and that has ideal operating characteristics even at room temperature. The result similar to this is La _2-x S
It was also obtained with a capacitor using r _x CuO ₄ (x = 1/4). Further, in the electric storage device using La _2−x Sr _x CuO ₄ (x = 1/8), some effect of increasing the capacity was observed.

It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0029]

As described above in detail, according to the present invention, there is provided a capacitor using a super-dielectric, which includes a super-dielectric layer and an ordinary super-dielectric layer arranged in series. Since the dielectric layer, the metal electrode connected to the super-dielectric layer, and the metal electrode connected to the normal dielectric layer are provided, it is possible to obtain a capacitor having an extremely large capacitance. .

As the super-dielectric layer, a lanthanum-based superconductor La _2-x Sr _x CuO ₄ crystal having a carrier doping amount of x = 1/4 ⁿ and x = ^{2/4 n} (where n is Positive integer) or a copper oxide in which the number of hole carriers per CuO ₂ unit of the two-dimensional conductive layer is 1/4 ⁿ or 2/4 ⁿ , or an oxide having holes having the characteristics corresponding thereto as carriers.
Alternatively, a two-dimensional conductive substance having holes or electrons as carriers can be used.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a capacitor using a superdielectric of the present invention.

FIG. 2 is an explanatory diagram of polarization of a superconductor and a superdielectric.

FIG. 3 is a diagram showing polarization states of vacuum, a normal dielectric substance, and a super-dielectric.

FIG. 4 is a diagram showing an experimental result of a capacitor using the superdielectric of the present invention.

FIG. 5 is a configuration diagram of a conventional electric storage device.

[Explanation of symbols]

 11 Super Dielectric Layer 12 Ordinary Dielectric Layer 13 Anode Metal Electrode 14 Cathode Metal Electrode 15 DC Power Supply

Claims (5)

[Claims] 1. A super-dielectric layer, (b) a normal dielectric layer arranged in series with the super-dielectric layer, and (c) a metal electrode connected to the super-dielectric layer. (D) A capacitor using a super-dielectric, comprising a metal electrode connected to the ordinary dielectric layer. 2. The capacitor using the super-dielectric according to claim 1, wherein the super-dielectric layer is a lanthanum-based superconductor La.
A capacitor using a super dielectric made of _2-x Sr _x CuO ₄ crystal. 3. A capacitor using the superdielectric according to claim 2, wherein the lanthanum-based superconductor La _2-x Sr _x Cu is used.
The O ₄ crystal has a carrier doping amount of x = 1/4 ⁿ or x =
A capacitor using a super-dielectric that is 2/4 ⁿ (where n is a positive integer). 4. The capacitor using the super dielectric according to claim 1, wherein the super dielectric layer is a two-dimensional conductive layer and the number of hole carriers per CuO ₂ unit is ¼ ⁿ or 2/4.
A capacitor using a superdielectric, which is a two-dimensional conductive material having holes or electrons equivalent to the carrier state of ⁿ (where n is a positive integer), as carriers. 5. A capacitor using the superdielectric according to claim 4, wherein the two-dimensional conductive material is an oxide.