JP6791350B2 - Composite oxide - Google Patents

Description

The present invention relates to composite oxides, specifically composite oxides exhibiting an electrocaloric effect.

Currently, as a cooling system, a system using a gaseous refrigerant is the mainstream. As a new cooling system to replace this, a solid-state cooling system using the electrocaloric effect (ECE), which is an endothermic phenomenon that utilizes the change in entropy when an electric field is applied to a ferroelectric or antiferroelectric, is available. It is being considered.

As a material showing the electric heat effect as described above, for example, in Non-Patent Document _{1, Pb 0.99 [(Zr 1-} x Sn x) 1-y Ti y] 0.98 Nb 0.02 O 3 ( At x = 0.4, y = 0.06 to 0.09; x = 0.5, y = 0.04 to 0.12; and x = 0.6, y = 0.08 to 0.20) Niobium-added lead zirconate titanate antiferroelectric ceramics with the shown perovskite structure are disclosed. In Non-Patent Document 1, the electrocaloric effect of this ceramic is evaluated by the Direct measurement method, and when x = 0.6 and y = 0.14, ΔT = 0.6K (14 kV) at 370 K (97 ° C.). / Cm) can be achieved.

Further, Non-Patent Document 2 discloses a commercial multilayer ceramic capacitor based on BaTiO ₃ . The electric heat effect of this ceramic capacitor is evaluated by the Direct measurement method, and it is described that an electric field of 30 MV / m can be applied and that ΔT = 0.55 K can be achieved.

V. V. Shvartsman et al., Ferroelectrics, 258, 13-20 (2001) S Kar-Narayan and N D Mathur, J. Phys. D: Appl. Phys.43 (2010) 032002 (4pp)

In order to utilize the electric heat effect for refrigeration and freezing applications, it has high insulation and high breakdown voltage, a high electric field can be applied, the volume that contributes to heat absorption and heat generation with a single element is large, and the temperature is wide below room temperature. A material that exhibits an electrocaloric effect in the region is required. However, the ceramics disclosed in Non-Patent Document 1 have a problem that it is difficult to apply a high electric field and the temperature at which a sufficiently large electric calorific value effect is exhibited is 320 K (47 ° C.) or higher, which is relatively high. is there. Further, since the ceramics disclosed in Non-Patent Document 2 use a ferroelectric material based on BaTIO ₃ having a small electric calorific value effect, there is a problem that ΔT is small.

Therefore, an object of the present invention is to provide a composite oxide that exhibits a large electrocaloric effect even at room temperature or lower.

As a result of diligent studies, the present inventors have doped Pb (Zr, Sn, Ti) composite oxide with Nb, Ta, W or Mo, and further set these ratios within a predetermined range at room temperature. We have found that we can provide a material that exhibits a large electrocaloric effect even below, and have completed the present invention.

According to the first gist of the present invention, the following formula (I) or (II):
_{Pb 1-z / 2 ([} Zr x Sn 1-x] 1-y Ti y) 1-z M 1 z O 3 (I)
_{Pb 1-z ([Zr x} Sn 1-x] 1-y Ti y) 1-z M 2 z O 3 (II)
[During the ceremony:
M ¹ is Nb or Ta,
M ² is W or Mo,
x is 0.50 or more and 0.65 or less,
y is 0.03 or more and 0.07 or less,
z is 0.01 or more and 0.03 or less. ]
Provided is a composite oxide represented by, which causes a phase transition between a ferroelectric and an antiferroelectric at a temperature of 25 ° C. or lower.

According to the second gist of the present invention
A composite oxide containing Pb, Zr, Sn, Ti and M ¹ or M ² .
A phase transition between the ferroelectric and antiferroelectric occurs at temperatures below 25 ° C.
M ¹ is Nb or Ta,
M ² is W or Mo,
The molar portion containing Zr in a total of 100 molar portions of Zr and Sn is the p molar portion.
The molar portion of Ti contained in a total of 100 molar portions of Zr, Sn and Ti is the q molar portion.
Zr, Sn, the content molar portion of ^{M 1} or ^{M 2} in a total of 100 molar parts of Ti and ^{M 1} or ^{M 2,} an r molar parts,
p is 50 or more and 65 or less,
q is 3 or more and 7 or less,
r is 1 or more and 3 or less,
Composite oxides are provided.

According to the third gist of the present invention, it is an endothermic element including a laminated body having a plurality of electrode layers and a plurality of dielectric layers located between the electrode layers.
The dielectric layer is composed of the above composite oxide.
The thickness of the dielectric layer is 5 μm or more.
An endothermic element is provided.

According to the fourth gist of the present invention, there is provided an electronic device having the above-mentioned endothermic element.

According to the fifth gist of the present invention
A method for producing a composite oxide containing Pb, Zr, Sn, Ti and M ¹ (M ¹ is Nb or Ta) or M ² (M ² is W or Mo).
Oxides or salts of Pb, Zr, Sn, Ti and M ¹ or M ² ,
The molar portion containing Zr in a total of 100 molar portions of Zr and Sn is the p molar portion.
The molar portion of Ti contained in a total of 100 molar portions of Zr, Sn and Ti is the q molar portion.
Zr, Sn, the content molar portion of ^{M 1} or ^{M 2} in a total of 100 molar parts of Ti and ^{M 1} or ^{M 2,} an r molar parts,
p is 50 or more and 65 or less,
q is 3 or more and 7 or less,
When r contains 1 or more and 3 or less M ¹ , the molar portion of Pb contained in a total of 100 molar parts of Zr, Sn, Ti and M ¹ is (100- (r / 2)) molar parts or M ² . When included, the molar portion of Pb contained in a total of 100 mol parts of Zr, Sn, Ti and M ² is (100-r) mol parts.
Provided is a production method in which the mixture is mixed at a ratio of the above, and then fired in a lead atmosphere having the above ratio after firing.

According to the present invention, Pb (Zr, Sn, Ti) composite oxide is doped with Nb, Ta, W or Mo, and the ratio thereof is set within a predetermined range to obtain a large amount of electric heat even at room temperature or lower. A material showing an effect can be provided.

FIG. 1 is a schematic cross-sectional view of an endothermic element used in the present invention. FIG. 2 is a schematic cross-sectional view of another endothermic element used in the present invention. FIG. 3 is a composition triangular phase diagram of Zr, Sn and Ti for the sample of M ¹ = Nb and z = 0.02 in the example. FIG. 4 is a graph showing the temperature dependence of ΔT when an electric field is applied with respect to sample number 8.

The material exhibiting the electrocaloric effect of the present invention is a Pb (Zr, Sn, Ti) composite oxide doped with M ¹ or M ² .

In one embodiment, the composite oxide of the present invention has the following formula (I) or (II):
_{Pb 1-z / 2 ([} Zr x Sn 1-x] 1-y Ti y) 1-z M 1 z O 3 (I)
_{Pb 1-z ([Zr x} Sn 1-x] 1-y Ti y) 1-z M 2 z O 3 (II)
[During the ceremony:
M ¹ is Nb or Ta,
M ² is W or Mo,
x is 0.50 or more and 0.65 or less,
y is 0.03 or more and 0.07 or less,
z is 0.01 or more and 0.03 or less. ]
It is a composite oxide represented by, and is a composite oxide that causes a phase transition between a ferroelectric and an antiferroelectric at a temperature of 25 ° C. or lower.

In the above formula, x is 0.50 or more and 0.65 or less, preferably more than 0.60 and 0.65 or less, and can be, for example, 0.65.

In the above formula, y is 0.03 or more and 0.07 or less, preferably 0.03 or more and 0.05 or less, preferably 0.03 or more and less than 0.04, for example, 0.03, 0.04 or 0.05. Can be.

By setting x and y in the above range, the composite oxide of the present invention can exhibit a large electrocaloric effect at room temperature or lower, for example, 25 ° C. or lower. Further, the composite oxide of the present invention may have high withstand voltage resistance and the like.

In the above formula, z can be 0.01 or more and 0.03 or less, for example, 0.01, 0.02 or 0.03.

By setting z in the above range, the composite oxide of the present invention can have high insulating properties over a wide temperature range.

In a preferred embodiment, x is 0.50 or more and 0.65 or less, preferably greater than 0.50 and 0.65 or less, y is 0.05, and z is 0.01 or more and 0.03 or less. Within such a range, the composite oxide of the present invention can have a larger electric heat effect, higher withstand voltage, etc. at room temperature or lower, for example, 25 ° C. or lower.

Preferably, the composite oxide of the present invention has the formula (I):
_{Pb 1-z / 2 ([} Zr x Sn 1-x] 1-y Ti y) 1-z M 1 z O 3 (I)
It is a composite oxide represented by. More preferably, the composite oxide of the present invention has x of 0.50 or more and 0.65 or less, preferably more than 0.50 and 0.65 or less, y of 0.05, and z of 0.01. It is a composite oxide represented by the formula (I) which is 0.03 or less. Particularly preferably, the composite oxide of the present invention has M ¹ of Nb, x of 0.50 or more and 0.65 or less, preferably more than 0.50 and 0.65 or less, and y of 0.05. It is a composite oxide represented by the formula (I) in which z is 0.01 or more and 0.03 or less.

In one embodiment, the composite oxide of the present invention
A composite oxide containing Pb, Zr, Sn, Ti and M ¹ or M ² .
A phase transition between the ferroelectric and antiferroelectric occurs at temperatures below 25 ° C.
M ¹ is Nb or Ta,
M ² is W or Mo,
The molar portion containing Zr in a total of 100 molar portions of Zr and Sn is the p molar portion.
The molar portion of Ti contained in a total of 100 molar portions of Zr, Sn and Ti is the q molar portion.
Zr, Sn, the content molar portion of ^{M 1} or ^{M 2} in a total of 100 molar parts of Ti and ^{M 1} or ^{M 2,} an r molar parts,
p is 50 or more and 65 or less,
q is 3 or more and 7 or less,
r is 1 or more and 3 or less,
It can be a composite oxide.

The p is 50 or more and 65 or less, preferably larger than 60 and 65 or less, and can be 65, for example.

The q can be 3 or more and 7 or less, preferably 3 or more and 5 or less, preferably 3 or more and less than 4, for example, 3, 4 or 5.

By setting p and q in the above ranges, the composite oxide of the present invention can exhibit a large electrocaloric effect at room temperature or lower, for example, 25 ° C. or lower. Further, the composite oxide of the present invention may have high withstand voltage resistance and the like.

The r can be 1 or more and 3 or less, for example 1, 2 or 3.

By setting r to the above range, the composite oxide of the present invention can have high insulating properties over a wide temperature range.

In a preferred embodiment, p is 50 or more and 65 or less, preferably greater than 50 and 65 or less, q is 5, and r is 1 or more and 3 or less. Within such a range, the composite oxide of the present invention can have a larger electric heat effect, higher withstand voltage, etc. at room temperature or lower, for example, 25 ° C. or lower.

Preferably, the composite oxide of the present invention is the composite oxide containing M ^1. More preferably, the composite oxide of the present invention is the above-mentioned composite oxide having p of 50 or more and 65 or less, preferably more than 50 and 65 or less, q of 5, and r of 1 or more and 3 or less. Particularly preferably, the composite oxide of the present invention comprises ^{M 1, M 1} is Nb, p is 50 or more 65 or less, preferably greater than 50 65 or less, q is 5, r is 1 It is a composite oxide having a value of 3 or more.

In one embodiment
When M ¹ is contained, the molar portion of Pb contained in a total of 100 molar parts of Zr, Sn, Ti and M ¹ is (100- (r / 2)) molar parts.
When M ² is contained, the molar portion of Pb contained in a total of 100 molar parts of Zr, Sn, Ti and M ² is the (100-r) molar portion.

The composite oxide of the present invention may have a perovskite structure.

The composite oxide of the present invention exhibits a large electric calorific value effect in a wide temperature range of room temperature or lower, for example, 25 ° C. or lower, particularly 25 ° C. or lower. Although the present invention is not bound by any theory, the composite oxide of the present invention has three phases of ferroelectric, antiferroelectric and normal dielectric over a wide temperature range, and thus is from ferroelectric to normal dielectric. than the phase transition point (T _C) strength of a conventional only can obtain a great effect in the dielectric is considered to exhibit large electrical caloric effect over a wide temperature range.

As described above, the composite oxide of the present invention exhibits a large electrocaloric effect by exhibiting a phase transition between a ferroelectric and an antiferroelectric at a temperature of 25 ° C. or lower. In particular, when an electric field of 10 MV / m is applied at a temperature of 25 ° C. or lower, preferably in a temperature range of −50 ° C. or higher and 25 ° C. or lower, 0.50 K or higher, preferably 0.60 K or higher, more preferably 0. It shows ΔT of .70K or more.

Here, ΔT means a temperature change of the sample caused by application and removal of an electric field to the sample. ΔT can be obtained by directly attaching an ultrafine thermocouple to the sample and measuring the temperature change when an electric field is applied and when the electric field is removed. Further, as for the method of measuring ΔT, a platinum resistance temperature detector or a thermistor element may be directly attached as long as the temperature of the sample can be measured, or an IR camera (infrared camera / thermoviewer) may be used in a non-contact manner. Good.

In addition, the composite oxide of the present invention can have high insulating properties over a wide temperature range.

The composite oxide of the present invention is, for example, 1 × 10 ⁵ Ω · cm or more, preferably 1 × 10 ¹⁶ Ω · cm or less, preferably at a temperature of 25 ° C. or lower, preferably -50 ° C. or higher and 25 ° C. or lower. Has a specific resistance of 1 × 10 ⁹ Ω · cm or more, 1 × 10 ¹⁵ Ω · cm or less, more preferably 1 × 10 ¹⁰ Ω · cm or more, and 1 × 10 ¹⁴ Ω · cm or less.

In addition, the composite oxide of the present invention may have high withstand voltage characteristics over a wide temperature range.

The composite oxide of the present invention is, for example, at a temperature of 25 ° C. or lower, preferably in a temperature range of −50 ° C. or higher and 25 ° C. or lower, at 10 MV / m or higher, preferably 20 MV / m or higher, more preferably 30 MV / m. Indicates withstand voltage.

In addition, the composite oxide of the present invention can undergo a phase transition even at a relatively low electric field, that is, it can exhibit a large electrocaloric effect. Therefore, the composite oxide of the present invention can exhibit a high electrocaloric effect even in a relatively thick shape in which a strong electric field is difficult to apply.

The composite oxide of the present invention can be obtained, for example, by mixing Pb, Zr, Sn, Ti and an oxide or salt of M ¹ or M ² and firing. Lead volatilization from the obtained composite oxide can be suppressed by mixing Pb, Zr, Sn, Ti and M ¹ or M ² in a predetermined ratio and firing in a lead atmosphere. ..

That is, the present invention is a method for producing a composite oxide containing Pb, Zr, Sn, Ti and M ¹ (M ¹ is Nb or Ta) or M ² (M ² is W or Mo). There,
Oxides or salts of Pb, Zr, Sn, Ti and M ¹ or M ² , preferably oxides.
The molar portion containing Zr in a total of 100 molar portions of Zr and Sn is the p molar portion.
The molar portion of Ti contained in a total of 100 molar portions of Zr, Sn and Ti is the q molar portion.
Zr, Sn, the content molar portion of ^{M 1} or ^{M 2} in a total of 100 molar parts of Ti and ^{M 1} or ^{M 2,} an r molar parts,
p is 50 or more and 65 or less,
q is 3 or more and 7 or less,
r is mixed at a ratio of 1 or more and 3 or less,
When M ¹ is contained, the molar portion of Pb contained in a total of 100 mol parts of Zr, Sn, Ti and M ¹ is (100- (r / 2)) mol parts, or when M ² is contained, Zr, Sn, The molar portion of Pb contained in a total of 100 mol parts of Ti and M ² is (100-r) mol parts,
Provided is a manufacturing method by firing in a lead atmosphere such that.

Preferably, in the mixing step of the above production method, when M ¹ is further contained, the molar portion of Pb contained in a total of 100 mol parts of Zr, Sn, Ti and M ¹ is (100- (r / 2)) mol. as is part, or if it contains M ^2, Zr, Sn, the content molar portion of Pb to the total 100 molar parts of Ti and ^{M 2,} as a (100-r) parts by mole,
Oxides or salts of Pb, Zr, Sn, Ti and M ¹ or M ² , preferably oxides, are mixed.

Since the composite oxide of the present invention exhibits an excellent electrocaloric effect, it can be used as a material for an endothermic element.

Hereinafter, the endothermic element of the present invention will be described with reference to the drawings. However, the shape and arrangement of the endothermic element and each component of the following embodiments are not limited to the illustrated examples.

As shown in FIG. 1, the endothermic element 1a of the first embodiment of the present invention is a dielectric composed of a pair of electrodes 2 and 4 and a composite oxide of the present invention located between the pair of electrodes. It has a body part 6. When a voltage is applied between the electrodes 2 and 4, an electric field is applied to the dielectric portion 6. As a result, the dielectric portion 6 generates heat. Further, when the voltage between the electrodes 2 and 4 is removed, the electric field applied to the dielectric portion 6 disappears. As a result, the dielectric portion 6 absorbs heat.

The shape of the dielectric portion 6 is not particularly limited, and can be formed into, for example, a sheet shape, a block shape, or various other shapes. The molding method is not particularly limited, and compression, sintering, or the like can be used. Further, it may be molded by mixing with a binder such as resin or glass.

The material constituting the electrodes 2 and 4 is not particularly limited, and examples thereof include Ag, Cu, Pt, Ni, Al, Pd, Au, and alloys thereof (for example, Ag-Pd and the like). Of these, Pt, Ag, Pd or Ag-Pd are preferable.

The electrodes 2 and 4 may have a function of transferring the amount of heat of the dielectric portion in addition to the function of applying an electric field to the dielectric portion. Therefore, from the viewpoint of heat transfer, the material constituting the electrode is preferably a material having high thermal conductivity, for example, Ag.

The shapes of the electrodes 2 and 4 are not particularly limited, but from the viewpoint of heat transfer, a shape that covers the entire surface of one of the dielectric portions 6 is preferable.

Since the endothermic element of the present invention exhibits an excellent electric heat quantity effect, it can be used as a heat management element, particularly a cooling element.

The endothermic element of the present invention uses a dielectric portion made of a material that exhibits a large electrocaloric effect at room temperature or lower, particularly −50 ° C. or higher and 25 ° C. or lower. Therefore, the endothermic element of the present invention can be suitably used especially in refrigeration and freezing applications.

In a preferred embodiment, the endothermic element of the present invention may include a laminate of a plurality of electrodes and a plurality of dielectric layers. That is, the present invention is an endothermic element including a laminated body having a plurality of electrode layers and a plurality of dielectric layers located between the electrode layers.
The dielectric layer is composed of the composite oxide of the present invention.
The thickness of the dielectric layer is 5 μm or more.
Provided is an endothermic element.

For example, the endothermic element 1b as shown in FIG. 2 can be used. In the endothermic element 1b of the second embodiment of the present invention, a plurality of internal electrodes 12a and 12b and a plurality of dielectric portions 14 are alternately laminated. The internal electrodes 12a and 12b are electrically connected to the external electrodes 16a and 16b arranged on the end faces of the endothermic element 1b, respectively. When a voltage is applied from the external electrodes 16a and 16b, an electric field is formed between the internal electrodes 12a and 12b. This electric field causes the dielectric portion 14 to generate heat. Further, when the voltage is removed, the electric field disappears, and as a result, the dielectric portion 14 absorbs heat.

In one embodiment, the dielectric portions 14 to be laminated may all have the same composition, or one or more dielectric portions having different compositions may be laminated.

With such a structure, a stronger electric field can be applied to the dielectric portion 14, and a larger ΔT can be obtained. In addition, since the internal electrode also functions as a heat propagation path inside the dielectric portion, efficient heat management is possible.

The thickness of the dielectric layer can be 5 μm or more, preferably 10 μm or more, and more preferably 15 μm or more.

In the endothermic and heat absorbing elements 1a and 1b described above, the electrodes and the dielectric portion are substantially in contact with each other on the entire surface, but the present invention is not limited to such a structure, and an electric field can be applied to the dielectric portion. It may be a structure. Further, the endothermic elements 1a and 1b have a rectangular parallelepiped block shape, but the shape of the endothermic element of the present invention is not limited to this, and may be, for example, a cylindrical shape or a sheet shape, and further uneven or through holes. Etc. may be possessed.

The endothermic element of the present invention mainly absorbs heat generated by a heat generating source when the electric field is released and heat is absorbed, or when the temperature of the endothermic element drops due to this endothermic heat absorption. Further, the endothermic element of the present invention mainly releases the absorbed heat to the outside when an electric field is applied to dissipate heat. Therefore, the endothermic element of the present invention can be used as a cooling device.

Although the endothermic element of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications can be made.

The present invention also provides an electronic component having the heat absorbing / generating element of the present invention, and an electronic device having the heat absorbing / generating element or the electronic component of the present invention.

The electronic components are not particularly limited, but for example, a central processing device (CPU), a hard disk (HDD), a power management IC (PMIC), a power amplifier (PA), a transceiver IC, a voltage regulator (VR), and the like. Integrated circuits (ICs), light emitting diodes (LEDs), incandescent bulbs, light emitting elements such as semiconductor lasers, components that can be heat sources such as field effect transistors (FETs), and other components such as lithium ion batteries, substrates, and heat sinks. , Parts generally used for electronic devices such as housings.

The electronic device is not particularly limited, and examples thereof include a freezer, a mobile phone, a smartphone, a personal computer (PC), a tablet terminal, a hard disk drive, and a data server after refrigeration.

-Preparation of heat absorbing and generating elements Pb _{1-z / 2} ([Zr _x Sn _1-x ] _1-y T _y ) In _1-z M ¹ _z O ₃ , Pb ₃ O ₄ , ZrO ₂ , SnO, TiO ₂ , And Nb ₂ O ₅ or Ta ₂ O ₅ were prepared, weighed to the compositions shown in the table below (sample numbers 1 to 50), and then pulverized and mixed by a ball mill. Similarly, in (Pb _{1- (3z / 2)} La _z ) ([Zr _x Sn _1-x ] _1-y T _y ) O ₃ , Pb ₃ O ₄ , ZrO ₂ , SnO, TiO ₂ , Nb ₂ O. ₅ or Ta ₂ O ₅ was prepared, weighed to the composition shown in the table below (sample number 51), and then pulverized and mixed by a ball mill. The obtained mixture was calcined in the air at 850 ° C. to prepare a calcined powder having a perovskite structure.

A polyvinyl butyral binder, a plasticizer, and ethanol were added to the calcined powder and wet-mixed with a ball mill to prepare a ceramic slurry. This ceramic slurry was sheet-molded by a doctor blade method so that the thickness of the dielectric layer after firing was 40 μm to obtain a green sheet. Next, Pt paste was screen-printed on the ceramic green sheet to form an internal electrode.

Next, a plurality of ceramic green sheets on which the internal electrodes were formed were laminated so that the pull-out sides of the internal electrodes were staggered to obtain a laminated green chip. The laminate 450 to 550 ° C. in ^{N 2:} Air = 1: degreased under 1 atmosphere, the alumina sealed sheath filled with 10g of PbZrO ₃ powder and 1~2g the green chip 4 hours firing at 1300 ° C. is performed , A ceramic laminate was obtained. Finally, Ag paste was applied as an external electrode and baked to prepare an endothermic element of the laminate.

The external dimensions of the laminated heat absorbing and generating element obtained as described above are 7.2 mm in width, 10 mm in length, and 0.92 mm in thickness, and the thickness of the dielectric layer interposed between the internal electrodes is 40 μm, and the internal electrodes. The thickness was 1.5 μm. The total number of effective dielectric layers was 20, and the counter electrode area per layer was 40.2 mm ² .

(Evaluation)
-Elemental analysis When the laminated endothermic element obtained above was dissolved and ICP (Inductively Coupled Plasma) analysis was performed, Zr, Sn, [ZrSn], Ti, [ZrSnTi], except for Pt, which is an internal electrode component, It was confirmed that each composition of M ¹ had a composition as shown in the above table.

-XRD structural analysis When the laminated endothermic element obtained above was analyzed by XRD (X-ray diffraction) structural analysis, it was confirmed that the main component had a perovskite structure.

・ Measurement of electric heat effect (ΔT measurement)
The electric calorific value effect characteristics of the laminated heat absorbing and generating element obtained above are obtained by directly attaching an ultrafine thermocouple of φ = 0.5 mm to the element and measuring the temperature change ΔT when an electric field is applied at 0 ° C, 25 ° C and 120 ° C. Measured by reading. The results are shown in the table below.

A sample with a ΔT of less than 0.5K at 25 ° C. and a sample with dielectric breakdown when an electric field of 10 MV / m is applied are NG because it is disadvantageous to use the electric heat effect as a heat management element in a refrigerator or freezer. , Others were G. Among the G samples, those having ΔT exceeding 0.5 K even at 0 ° C. were designated as G * as a more preferable composition. Furthermore, for the samples with G *, an electric field was applied up to 20 MV / m, and it was confirmed that ΔT exceeding 1 K was observed. The composition triangular phase diagram of Zr, Sn and Ti is shown in FIG. 3 for the samples of M ¹ = Nb and z = 0.02 (sample numbers 1 to 30). In FIG. 3, ● indicates G *, ○ indicates G, and × indicates NG. Further, FIG. 4 shows the temperature dependence of ΔT when the electric field of sample number 8 is applied.

In the above examples, Nb and Ta are added to the lead zirconate titanate antiferroelectric ceramics, but the added elements are not limited to this. Even if the average ionic radius of the additive element is smaller than the average ionic radius considering the composition ratio of B-site elements (Zr, Sn, Ti) of the base material ceramic that acts as a donor to the base material ceramic and has a perovskite structure. It is considered good. Elements satisfying this are Mo and W, and it is considered that the same effect can be obtained even when these are added.

The composite oxide of the present invention can be suitably used as a material for an endothermic element because it exhibits a high electrocaloric effect. The heat absorbing and generating element of the present invention can be used as a heat management element in a refrigerator or a freezer, and also as a cooling device for various electronic devices, for example, small electronic devices such as mobile phones in which heat countermeasure problems are becoming prominent. It can be used.

1a, 1b ... Endothermic element 2,4 ... Electrode 6 ... Dielectric part 12a, 12b ... Internal electrode 14 ... Dielectric layer 16a, 16b ... External electrode

Claims (10)

The following formula (I) :
_{Pb 1-z / 2 ([} Zr x Sn 1-x] 1-y Ti y) 1-z M 1 z O 3 (I)
[During the ceremony:
M ¹ is Ta ,
x is 0.50 or more and 0.65 or less,
y is 0.03 or more and 0.07 or less,
z is 0.01 or more and 0.03 or less. ]
A composite oxide represented by, which causes a phase transition between a ferroelectric and an antiferroelectric at a temperature of 25 ° C. or lower. The composite oxidation represented by the formula (I) according to claim 1, wherein x is 0.50 or more and 0.65 or less, y is 0.05, and z is 0.01 or more and 0.03 or less. Stuff. Pb, a composite oxide containing Zr, Sn, Ti and M ^1,
A phase transition between the ferroelectric and antiferroelectric occurs at temperatures below 25 ° C.
M ¹ is Ta ,
The molar portion containing Zr in a total of 100 molar portions of Zr and Sn is the p molar portion.
The molar portion of Ti contained in a total of 100 molar portions of Zr, Sn and Ti is the q molar portion.
The molar portion of M ¹ in a total of 100 molar portions of Zr, Sn, Ti and M ¹ is the r molar portion.
p is 50 or more and 65 or less,
q is 3 or more and 7 or less,
r is 1 or more and 3 or less,
Composite oxide. Zr, Sn, the molar portions of Pb to the total 100 molar parts of Ti and ^{M 1} is, (100- (r / 2) ) Ru molar portion der,
The composite oxide according to claim 3. The composite oxide according to claim 3 or 4, wherein p is 50 or more and 65 or less, q is 5, and r is 1 or more and 3 or less. The composite oxide according to any one of claims 1 to 5, wherein the composite oxide has a perovskite structure as a main component. An endothermic element comprising a laminate having a plurality of electrode layers and a plurality of dielectric layers located between the electrode layers.
The dielectric layer is composed of the composite oxide according to any one of claims 1 to 6.
The thickness of the dielectric layer is 5 μm or more.
Endothermic element. An electronic device having the endothermic element according to claim 7. A method for producing a composite oxide containing Pb, Zr, Sn, Ti and M ¹ (M ¹ is Ta ) .
Oxides or salts of Pb, Zr, Sn, Ti and M ¹
The molar portion containing Zr in a total of 100 molar portions of Zr and Sn is the p molar portion.
The molar portion of Ti contained in a total of 100 molar portions of Zr, Sn and Ti is the q molar portion.
The molar portion of M ¹ in a total of 100 molar portions of Zr, Sn, Ti and M ¹ is the r molar portion.
p is 50 or more and 65 or less,
q is 3 or more and 7 or less,
r is 1 or more and 3 or less,
Zr, Sn, the content molar portion of Pb to the total 100 molar parts of Ti and ^{M 1, (100- (r /} 2)) parts by mole
Weight ratio to form the method by firing at the rate as under lead atmosphere such that after firing. The method for producing a composite oxide according to claim 9, wherein the composite oxide has a perovskite structure as a main component.

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