JP6424972B2 - Magnetic composition - Google Patents

Description

  The present invention relates to a magnetic composition, in particular, a magnetic composition exhibiting an electrocaloric effect, and a heat transfer device using the same.

  In recent years, in electronic devices such as small portable devices (smartphones and tablet PCs) and data servers, the performance of the devices has been reduced due to heat generation from central processing units (CPUs) and hard disks (HDDs), etc. Problems such as shortening lives and failures have become apparent. For such problems, heat management in electronic devices is important. However, small electronic devices such as smartphones have small power supply capacity and do not have a space in which a large cooling device can be installed. Therefore, in such small-sized electronic devices, at present, the control of temperature is only by means of heat radiation through the housing, and the heat source and the housing are thermally coupled by a thermal sheet or the like to release the heat. On the other hand, in large-scale electronic devices such as servers, since there is sufficient power supply capacity and space, air conditioning equipment such as air conditioners, Peltier cooling devices, etc. are used.

On the other hand, Non-Patent Document 1 reports Pb _0.8 Ba _0.2 ZrO ₃ as a material exhibiting an electrocaloric effect (hereinafter also referred to as “EC effect”). In Non-Patent Document 1, the Pb _0.8 Ba _0.2 ZrO ₃ is formed into a thin film by a sol-gel method, and the EC effect is measured. As a result, it is described that the Pb _0.8 Ba _0.2 ZrO ₃ thin film described in Non-Patent Document 1 exhibits a large EC effect at 290 K near room temperature. The electrocalorific effect is an endothermic phenomenon caused by a change in entropy when the electric dipole moment in a substance is aligned or disturbed by a change in electric field.

A Giant Electrocaloric Effect in Nanoscale Antiferroelectric and Ferroelectric Phases Coexisting in a Relaxor Pb0.8Ba0.2ZrO3 Thin Film at Room Temperature, Biaolin Peng, Huiqing Fan, and Qi Zhang, Advanced Functional Materials, Volume 23, Issue 23, pages 2987-299, June 20, 2013

  In a small electronic device, the heat dissipation through the above-described housing is limited because the surface area of the housing is limited. Therefore, the temperature of each heat source is measured, and when the temperature reaches a predetermined temperature or more, the performance of the CPU or the like is restricted (heat generation itself is suppressed). That is, the temperature rise of the housing sometimes hinders the performance of the CPU or the like.

  Further, in a large-sized electronic device, although a sufficient cooling effect can be obtained by the above-described air conditioning equipment and the like, since the power consumption is very large, there is a problem that power cost is required for heat management.

  Therefore, the present inventor has focused on the above-described electric calorific effect and has come to think of using a magnetic composition such as a Pb-Ba-Zr composite oxide exhibiting this electric calorific effect for a heat transfer device. Although the control voltage is required in this phenomenon, the complex oxide is a highly insulating ferroelectric material, so the power consumption is very small, the power cost is low, and even a small portable device with a limited power supply capacity. It is usable.

  On the other hand, when using a magnetic composition as described in Non-Patent Document 1 for thermal management of large electronic devices such as servers that need to handle a larger amount of heat, a higher electric field is applied to the magnetic composition to increase You need to get an EC effect. However, the magnetic composition as described in Non-Patent Document 1 has a problem that a leak current may occur when a high voltage is applied. This problem is particularly pronounced in high temperature environments, as magnetic compositions generally decrease in insulation with increasing temperature.

  An object of the present invention is to provide a magnetic composition exhibiting a large electrocalorific effect and having a high insulating property, and a heat transfer device using the magnetic composition.

  As a result of intensive studies to solve the above problems, the present inventor has prepared the content of Pb to a specific amount in the Pb-Ba-Zr complex oxide, and further, trivalent, pentavalent or hexavalent. It has been found that by doping a metal of the formula (I), a magnetic composition exhibiting a large electrocalorific effect and a high insulating property can be obtained, resulting in the present invention.

According to a first aspect of the present invention,
_{100 {(Pb (1-x} ) y Ba x) ZrO 3} · αM1
[Wherein, M 1 is at least one element selected from La, Bi, V, Nb, Ta, Sb, Mo and W,
x is 0.15 or more and 0.30 or less,
y is 0.94 or more and 1.01 or less,
α is 0.1 or more and 1.0 or less. ]
There is provided a magnetic composition comprising as a main component a composite oxide represented by

According to a second aspect of the present invention, there is provided a composite oxide comprising Pb, Ba, Zr and M2, wherein
M2 is at least one element selected from La, Bi, V, Nb, Ta, Sb, Mo and W,
The molar content of Ba relative to 100 molar parts of Zr is p molar part,
The molar content of Pb relative to 100 molar parts of Zr is q molar parts,
p is 15 or more and 30 or less,
q is (100−p) × r (wherein r is 0.94 or more and 1.01 or less),
The magnetic composition containing as a main component a composite oxide is characterized in that the content molar part of M2 is from 0.1 molar part to 1.0 molar part with respect to 100 mol parts of Zr.

  According to a third aspect of the present invention, there is provided a heat transfer device comprising at least two electrodes and a dielectric part composed of the above-mentioned magnetic composition located between the electrodes.

  According to a fourth aspect of the present invention, there is provided an electronic component comprising the above heat transfer device.

  According to a fifth aspect of the present invention, there is provided an electronic device comprising the above heat transfer device or the above electronic component.

According to the present invention, the magnetic composition having a specific composition, e.g., _{100 {(Pb (1-x} ) y Ba x) ZrO 3} · αM1
[Wherein, M 1 is at least one selected from La, Bi, V, Nb, Ta, Sb, Mo and W,
x is 0.15 or more and 0.30 or less,
y is 0.94 or more and 1.01 or less,
α is 0.1 or more and 1.0 or less. ]
By using the material represented by the above, it is possible to provide a magnetic composition having a large electric calorific effect and high insulation.

FIG. 1 is a schematic cross-sectional view of a heat transfer device according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view of a heat transfer device according to a second embodiment of the present invention. FIG. 3 is a temperature-ΔT diagram (10 MV / m) for samples 95 and 101 in the example.

  Hereinafter, the magnetic composition of the present invention will be described.

In one aspect, the magnetic composition of the present invention contains, as a main component, a complex oxide represented by the following formula.
_{100 {(Pb (1-x} ) y Ba x) ZrO 3} · αM1

  The above-mentioned "main component" means a component contained most in the magnetic composition, and means, for example, a component contained at 50% by mass or more. In particular, the main component is 80% by mass or more, preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, for example, 98.0 to 99.8% by mass It means a component that is substantially 100% contained.

  In the above formula, x is 0.15 or more and 0.30 or less, preferably 0.20 or more and 0.30 or less, and more preferably 0.20 or more and 0.25 or less. By setting the x value in this range, it is possible to obtain greater insulation and EC effect. Further, by changing the value of x, it is possible to adjust the temperature at which the temperature change (hereinafter also referred to as “ΔT”) due to the change of the electric field shows a peak value.

  In the above formula, y is 0.94 or more and 1.01 or less.

  In one aspect, y is 0.94 or more and less than 1.00, for example, 0.94 or more and 0.999 or less, 0.95 or more and 0.999 or less, 0.965 or more and 0.999 or less, or 0. It may be 98 or more and 0.99 or less. When y is less than 1.00, grain growth hardly occurs, a dense magnetic composition is obtained, the insulation property is improved, and a larger electric field can be applied.

  In another aspect, y may be greater than 1.00 and 1.01 or less, preferably 1.001 or more and 1.010 or less, for example 1.005 or more and 1.010 or less. By making y larger than 1.00, the value of ΔT can be made larger.

In the above formula, M 1 is at least one doping element, and is selected from La, Bi, V, Nb, Ta, Sb, Mo and W. Among these doping elements, La and Bi are trivalent (i.e., La3 ⁺ and Bi3 ⁺ ), V, Nb, Ta and Sb are pentavalent (i.e., ^{V5 +} , Nb5 ⁺ , Ta5 ⁺ and Sb5 ⁺ ). And Mo and W are hexavalent (ie, Mo ⁶⁺ and W ⁶⁺ ).

  In the above formula, α is 0.1 or more and 1.0 or less, preferably 0.5 or more and 1.0 or less. By setting α in the range of 0.1 or more and 1.0 or less, the insulating property of the complex oxide is improved.

In one aspect, the magnetic composition of the present invention is a composite oxide comprising Pb, Ba, Zr and M2,
M2 is at least one selected from La, Bi, V, Nb, Ta, Sb, Mo and W,
The molar content of Ba relative to 100 molar parts of Zr is p molar part,
The molar content of Pb relative to 100 molar parts of Zr is q molar parts,
p is 15 or more and 30 or less,
q is (100−p) × r (wherein r is 0.94 or more and 1.01 or less),
The magnetic composition containing a composite oxide as a main component is characterized in that the content molar part of M2 is from 0.1 molar part to 1.0 molar part with respect to 100 mol parts of Zr. The composite oxide may correspond to the formula _{100 {(Pb (1-x} ) y Ba x) ZrO 3} composite oxide represented by · Arufaemu1 described above.

  In the above formula, p is 15 or more and 30 or less, preferably 20 or more and 30 or less, and more preferably 20 or more and 25 or less. By setting p to such a range, greater insulation and EC effect can be obtained. Also, by changing the value of p, the temperature at which ΔT exhibits a peak value can be adjusted.

  In one aspect, r is 0.94 or more and less than 1.00, for example, 0.94 or more and 0.999 or less, 0.95 or more and 0.999 or less, 0.965 or more and 0.999 or less, or 0. It may be 98 or more and 0.99 or less. By setting r to less than 1.00, grain growth hardly occurs, a dense magnetic composition is obtained, the insulation property is improved, and a larger electric field can be applied.

  In another aspect, r may be greater than 1.00 and 1.01 or less, preferably 1.001 or more and 1.010 or less, for example 1.005 or more and 1.010 or less. By making r larger than 1.00, the value of ΔT can be made larger.

In the above formula, M 2 is at least one doping element, and is selected from La, Bi, V, Nb, Ta, Sb, Mo and W. Among these doping elements, La and Bi are trivalent (that is, La ³⁺ and Bi ³⁺ ) and pentavalent (that is, V ⁵⁺ , Nb ⁵⁺ , Ta ⁵⁺ and Sb ⁵⁺ ), and Mo and W are hexavalent. ( ^I.e. , Mo6 ⁺ and ^{W6 +} ).

  The content mole part of M 2 with respect to 100 mole parts of Zr is 0.1 or more and 1.0 or less, preferably 0.5 or more and 1.0 or less. The insulating property of the composite oxide is improved by setting the content molar part of M2 to the range of 0.1 or more and 1.0 or less with respect to 100 parts by mol of Zr.

  The above-mentioned complex oxide of the present invention exhibits an EC effect of generating heat when an electric field is applied and absorbing heat when removed.

  The above complex oxide may be of the perovskite type.

  The magnetic composition of the present invention exhibits a large EC effect in a relatively wide lead composition area (ie, a relatively wide range of y or r) by having M1 or M2. Although the present invention is not bound by any theory, the reason is considered as follows. In ferroelectric ceramics having a perovskite structure containing Pb, Pb's of the ceramic volatilize due to the high vapor pressure of PbO during firing, so that it is considered that Pb's lose in the final composition after firing. EC characteristics at high temperature are susceptible to this Pb deficiency, and it is considered that the lead composition region where an effective EC effect can be obtained becomes very narrow. In the present invention, since the ion (M1 or M2) serving as a donor is added, it is considered that the influence of the Pb deficiency on the EC effect is reduced.

  In one aspect, the average particle diameter of the magnetic composition of the present invention may be preferably 0.5 μm or more, more preferably 0.5 μm to 10 μm, and still more preferably 1 μm to 5 μm. By having such a particle diameter, the withstand voltage of the dielectric portion and the electric heat effect can be further enhanced. The average particle size can be measured using an electron scanning microscope.

  The magnetic composition of the present invention exhibits a large EC effect, particularly at 323 K to 453 K (50 ° C. to 180 ° C.). Also, the magnetic composition of the present invention exhibits very high insulation. That is, a high voltage can be applied. Therefore, by using the magnetic composition of the present invention, a high electrocalorific effect can be obtained.

  The temperature range which shows the large EC effect can be adjusted by changing the content of Pb and Ba in the Pb-Ba-Zr composite oxide, in particular, the content of Ba.

The magnetic composition of the present invention exhibits high insulating properties, for example, 1 × 10 ⁸ Ω · cm or more and 1 × 10 ¹⁴ Ω · cm or less, preferably 1 × 10 ⁹ Ω · cm or more, 1 × 10 ¹² Ω It has a specific resistance of not more than cm, more preferably not less than 1 × 10 ⁹ Ω · cm and not more than 1 × 10 ¹¹ Ω · cm.

  The magnetic composition of the present invention exhibits a ΔT of 0.7 K or more, preferably 1.0 K or more, when an electric field of 20 MV / m is applied.

  The magnetic composition of the present invention exhibits a ΔT of 1.0 K or more, preferably 1.5 K or more, more preferably 2.0 K or more when an electric field of 30 MV / m is applied.

  The magnetic composition of the present invention exhibits a withstand voltage of 20 MV / m or more, preferably 30 MV / m or more.

  The magnetic composition of the present invention can be obtained, for example, by mixing and calcining oxides or salts of Pb, Ba, Zr and M1 or M2. The Pb content in the obtained composite oxide can be adjusted by mixing Pb, Ba, Zr and M1 or M2 in a predetermined ratio, and adjusting the Pb concentration in the atmosphere at the time of firing. it can.

  Next, the heat transfer device of the present invention will be described with reference to the drawings. However, the shape, arrangement, and the like of the heat transfer device and the respective components of the embodiments described below are not limited to the illustrated example.

  As shown in FIG. 1, the heat transport device 1a according to the first embodiment of the present invention is a dielectric composed of a pair of electrodes 2 and 4 and the magnetic composition of the present invention located between the pair of electrodes. And a body portion 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. Moreover, you may shape | mold by mixing with binders, such as resin or glass.

  Although it does not specifically limit as a material which comprises the electrodes 2 and 4, Ag, Cu, Pt, Ni, Al, Pd, Au, or these alloys (for example, Ag-Pd etc.) are mentioned. Among them, Pt, Ag, Pd or Ag-Pd is preferable.

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

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

  The heat transport device of the present invention uses a dielectric portion made of a material that exhibits a large EC effect, particularly at 323 K to 453 K (50 ° C. to 180 ° C.). Therefore, the heat transfer device of the present invention can be suitably used as a heat transfer device, typically a cooling device, in electronic devices such as smartphones, tablet PCs, and data servers whose temperature is between 323K and 453K. it can.

  As mentioned above, the magnetic composition of the present invention exhibits very high insulation. Therefore, the dielectric layer of the heat transfer device of the present invention has a high withstand voltage, and a high voltage can be applied between the electrodes, so that the change of the electric field can be increased. As a result, it is possible to increase the temperature change (ΔT) due to the change of the electric field.

  The heat transfer device in the first embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment, and various modifications are possible.

  For example, it can be set as the heat transport device 1b as shown in FIG. In the heat transport device 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 stacked. The internal electrodes 12a and 12b are electrically connected to external electrodes 16a and 16b disposed on the end face of the heat transfer device 1b, respectively. When a voltage is applied from the outer electrodes 16a and 16b, an electric field is formed between the inner electrodes 14a and 14b. The dielectric portion 14 generates heat due to this electric field. Also, when the voltage is removed, the electric field disappears, and as a result, the dielectric portion 14 absorbs heat.

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

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

  In the heat transport devices 1a and 1b described above, although the electrodes and the dielectric portion are substantially in contact with each other over the entire surface, 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. The heat transfer devices 1a and 1b are rectangular blocks, but the shape of the heat transfer device of the present invention is not limited to this, and may be, for example, a cylindrical shape or a sheet shape. And the like.

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

  The present invention also provides an electronic component comprising the heat transfer device of the present invention, and an electronic device comprising the heat transfer device or the electronic component of the present invention.

  The electronic components are not particularly limited. For example, central processing unit (CPU), hard disk (HDD), power management IC (PMIC), power amplifier (PA), transceiver IC, voltage regulator (VR), etc. Light emitting devices such as integrated circuits (ICs), light emitting diodes (LEDs), incandescent lamps, semiconductor lasers, parts that can be heat sources such as field effect transistors (FETs), and other parts such as lithium ion batteries, substrates, heat sinks , Parts generally used for electronic devices such as cases, etc.

  Examples of the electronic device include, but are not limited to, a mobile phone, a smartphone, a personal computer (PC), a tablet terminal, a hard disk drive, a data server, and the like.

- In the preparation of the thermal preparation of the conveying device _{100 {(Pb (1-x} ) y Ba x) ZrO 3} composite oxide represented by _{· αM1, Pb 3 O 4,} BaCO 3, ZrO 2 and _Nb 2 _{O 5} Alternatively, the Ta ₂ O ₅ raw material was weighed so as to have the composition shown in the following table, and pulverized and mixed with partially stabilized zirconia (PSZ) balls. After drying, the mixture was calcined at 1000 ° C. for 4 hours, and an organic solvent and a binder were added to the calcined powder to form a slurry by grinding and mixing. From the obtained slurry, a green sheet (40 μm in thickness) was formed by a doctor blade method. Pt paste was screen printed on the green sheet. A green sheet on which Pt paste was printed was pressure-bonded to form a layer structure as shown in FIG. 2, laminated, and then cut to prepare a green chip (5 mm × 7 mm × 0.5 mm).

After degreasing the green chip (2 g) at 450 ° C. to 550 ° C., the green chip (2 g) was sealed in an alumina hermetic sheath together with 10 g of PbZrO ₃ powder and fired at 1300 ° C. for 4 hours to produce a laminate chip. Ag paste was applied to both ends of the obtained laminate chip, and baking was performed to form an external electrode, whereby a sample (heat transfer device) having a structure shown in FIG. 2 was manufactured. The composition of the sample was confirmed by using ICP (inductively coupled plasma emission spectrometry) and XRF (fluorescent X-ray measurement) in combination.

(Evaluation)
・ Evaluation of electric heat effect (ΔT evaluation)
An ultrafine thermocouple was directly attached to the sample, and the temperature change (ΔT) was measured when an electric field was applied and when it was removed. The results are shown in the following table.

Operating temperature The temperature at which the value of ΔT measured above is maximum was determined as the operating temperature. The results are shown in the following table.

The judgment criteria are as follows.
When satisfy | filling the following (a)-(c), it determined with "G", and when not satisfy | filling even one, it determined with "NG."
(A) The temperature at which ΔT is maximum is in the range of 50 ° C. to 180 ° C.
(B) It is possible to apply an electric field of 20 MV / m, and ΔT is larger than 0.7K.
(C) An electric field of 30 MV / m can be applied.
Moreover, "x" shows that Joule heat arose, and "-" shows that it has not measured.

  Representatively, Sample No. 101 in which x is 0.3, y is 0.97, M1 is Nb, and α is 0.1, and Sample No. 95 not including M1 have an electric field of 10 MV / m. Temperature-delta T figure at the time of measuring by is shown in FIG.

  From the above results, it is possible that the sample within the scope of the present invention has high insulation and a large ΔT at an operating temperature suitable for use in electronic devices, and maintains insulation even with an electric field of 30 MV / m. confirmed. In particular, when x was 0.25 or less, it was confirmed that ΔT at an electric field application of 20 MV / m was 1.0 K or more, and the characteristics were further improved. Further, as shown in FIG. 3, it was confirmed that the sample 101 of the present invention doped with M1 has a higher ΔT as a whole than the sample 95 not doped with M1 and a wide usable area.

  The heat transport device of the present invention can be used as a cooling device for various electronic devices, for example, small electronic devices such as mobile phones in which the heat countermeasure problem has become significant.

DESCRIPTION OF SYMBOLS 1a, 1b ... Heat transport device 2, 4 ... Electrode 6 ... Dielectric material part 12a, 12b ... Internal electrode 14 ... Dielectric material part 16a, 16b ... External electrode

Claims (9)

Following formula:
_{100 {(Pb (1-x} ) y Ba x) ZrO 3} · αM1
[Wherein, M 1 is at least one selected from La, Bi, V, Nb, Ta, Sb, Mo and W,
x is 0.15 or more and 0.30 or less,
y is 0.965 or more and 0.999 or less ,
α is 0.1 or more and 1.0 or less. ]
The magnetic composition which has as a main component the complex oxide represented by these.   The magnetic composition according to claim 1, wherein M1 is at least one selected from Nb and Ta. A complex oxide containing Pb, Ba, Zr and M2,
M2 is at least one selected from La, Bi, V, Nb, Ta, Sb, Mo and W,
The molar content of Ba relative to 100 molar parts of Zr is p molar part,
The molar content of Pb relative to 100 molar parts of Zr is q molar parts,
p is 15 or more and 30 or less,
q is (100−p) × r (wherein r is 0.965 or more and 0.999 or less ),
A magnetic composition containing a composite oxide as a main component, wherein the molar content of M2 is from 0.1 to 1.0 molar parts with respect to 100 molar parts of Zr. The magnetic composition according to claim 3 , wherein M2 is at least one selected from Nb and Ta. Located between at least two electrodes and the electrodes ,
Following formula:
_{100 {(Pb (1-x} ) y Ba x) ZrO 3} · αM1
[Wherein, M 1 is at least one selected from La, Bi, V, Nb, Ta, Sb, Mo and W,
x is 0.15 or more and 0.30 or less,
y is 0.94 or more and 1.01 or less,
α is 0.1 or more and 1.0 or less. ]
A magnetic composition mainly composed of a complex oxide represented by
A complex oxide containing Pb, Ba, Zr and M2,
M2 is at least one selected from La, Bi, V, Nb, Ta, Sb, Mo and W,
The molar content of Ba relative to 100 molar parts of Zr is p molar part,
The molar content of Pb relative to 100 molar parts of Zr is q molar parts,
p is 15 or more and 30 or less,
q is (100−p) × r (wherein r is 0.94 or more and 1.01 or less),
The content mole part of M2 is 0.1 mole part or more and 1.0 mole part or less with respect to 100 mole parts of Zr
What is claimed is: 1. A heat transfer device comprising: a dielectric portion composed of a magnetic composition containing a composite oxide as a main component . The heat transfer device according to claim 5 , wherein the plurality of electrodes and the plurality of dielectric portions are alternately stacked. A cooling device, the heat delivery device as claimed in claim 5 or 6. An electronic component comprising the heat transfer device according to any one of claims 5 to 7 . An electronic device comprising the heat transfer device according to any one of claims 5 to 7 or the electronic component according to claim 8 .

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