Patent Publication Number: US-2023135523-A1

Title: Electrocaloric effect element, heat transfer device, semiconductor manufacturing device, and electrocaloric effect element control method

Description:
TECHNICAL FIELD 
     The present disclosure relates to an electrocaloric effect element, a heat transfer device, a semiconductor manufacturing device, and a method of controlling the electrocaloric effect element. 
     BACKGROUND 
     As a cooling device, electrocaloric effect elements using ferroelectric materials have been proposed (Non-Patent Document 1). 
     CITATION LIST 
     Non-Patent Document 
     
         
         [Non-Patent Document 1] Ma et al., Science 357, 1130-1134 (2017) 
       
    
     SUMMARY 
     Problem to be Solved by the Invention 
     The present disclosure provides an electrocaloric effect element, a heat transfer device, a semiconductor manufacturing device, and a method of controlling the electrocaloric effect element that can improve the efficiency of the heat transfer. 
     Means for Solving Problem 
     An electrocaloric effect element according to one aspect of the present disclosure includes a container having a first wall, an ionic liquid contained in the container, a first electrode disposed at an outer surface of the first wall, and a movable electrode disposed in the ionic liquid such that the movable electrode is movable in the ionic liquid. 
     Effect of Invention 
     According to the present disclosure, the efficiency of the heat transfer can be improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic diagram illustrating an electrocaloric effect element according to a first embodiment. 
         FIG.  2    is a cross-sectional view illustrating a movable electrode. 
         FIG.  3    is graphs indicating the thermodynamic cycle of ionic liquid. 
         FIG.  4    is a first diagram illustrating a cooling operation of the electrocaloric effect element according to the first embodiment. 
         FIG.  5    is a second diagram illustrating the cooling operation of the electrocaloric effect element according to the first embodiment. 
         FIG.  6    is a third diagram illustrating the cooling operation of the electrocaloric effect element according to the first embodiment. 
         FIG.  7    is a fourth diagram illustrating the cooling operation of the electrocaloric effect element according to the first embodiment. 
         FIG.  8    is a fifth diagram illustrating the cooling operation of the electrocaloric effect element according to the first embodiment. 
         FIG.  9    is a sixth diagram illustrating the cooling operation of the electrocaloric effect element according to the first embodiment. 
         FIG.  10    is a seventh diagram illustrating the cooling operation of the electrocaloric effect element according to the first embodiment. 
         FIG.  11    is a first diagram illustrating a temperature control operation of the electrocaloric effect element according to the first embodiment. 
         FIG.  12    is a second diagram illustrating the temperature control operation of the electrocaloric effect element according to the first embodiment. 
         FIG.  13    is a first diagram illustrating a heating operation of an electrocaloric effect element according to a second embodiment. 
         FIG.  14    is a second diagram illustrating the heating operation of the electrocaloric effect element according to the second embodiment. 
         FIG.  15    is a third diagram illustrating the heating operation of the electrocaloric effect element according to the second embodiment. 
         FIG.  16    is a fourth diagram illustrating the heating operation of the electrocaloric effect element according to the second embodiment. 
         FIG.  17    is a fifth diagram illustrating the heating operation of the electrocaloric effect element according to the second embodiment. 
         FIG.  18    is a sixth diagram illustrating the heating operation of the electrocaloric effect element according to the second embodiment. 
         FIG.  19    is a seventh diagram illustrating the heating operation of the electrocaloric effect element according to the second embodiment. 
         FIG.  20    is a first diagram illustrating a temperature control operation of the electrocaloric effect element according to the second embodiment. 
         FIG.  21    is a second diagram illustrating the temperature control operation of the electrocaloric effect element according to the second embodiment. 
         FIG.  22    is a diagram illustrating an example of a usage form of the electrocaloric effect element. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following, embodiments will be specifically described with reference to the accompanying drawings. In the present specification and the drawings, components having substantially the same functional structure may be referenced by the same reference numerals and the overlapped description may be omitted. 
     First Embodiment 
     The first embodiment relates to an electrocaloric effect element suitable for cooling.  FIG.  1    is a schematic diagram illustrating an electrocaloric effect element according to a first embodiment. 
     The electrocaloric effect element  1  according to the first embodiment includes a container  10 , a first electrode  21 , a second electrode  22 , a first insulating film  23 , a second insulating film  24 , an ionic liquid  50 , a movable electrode  40 , a first spacer  31 , and a second spacer  32 , as illustrated in  FIG.  1   . 
     The container  10  has a first wall  11  and a second wall  12  facing the first wall  11 . The container  10  is, for example, an insulating container. The container  10  is preferably flexible. The shape of the container  10  is not limited, but the container  10  may be, for example, in the form of a plate or a film. That is, the area of the first wall  11  and the second wall  12  is significantly greater than the distance between the first wall  11  and the second wall  12 . 
     The first electrode  21  is provided at the outer surface of the first wall  11 . The second electrode  22  is provided at the outer surface of the second wall  12 . The first electrode  21  and the second electrode  22  include a conductive oxide, such as indium tin oxide (ITO), for example. The first electrode  21  and the second electrode  22  are arranged parallel to each other. The distance between the first electrode  21  and the second electrode  22  is, for example, 100 μm or less. 
     The first insulating film  23  is provided between the first wall  11  and the first electrode  21 . The second insulating film  24  is provided between the second wall  12  and the second electrode  22 . The first insulating film  23  and the second insulating film  24  include, for example, silicon oxide (SiO 2 ), aluminum oxide (Al 2 O 3 ), silicon nitride (SiN), zirconium oxide (ZrO 2 ), hafnium oxide (HfO 2 ), titanium oxide (TiO 2 ), strontium titanate (STO), barium titanate (BTO), lead zirconate titanate (PZT), or calcium copper titanate (CCTO). 
     The ionic liquid  50  is contained in the container  10 . The ionic liquid  50  is liquid including cations and anions, and includes cation-anion pairs. When an electric field is not applied between the first electrode  21  and the second electrode  22 , the orientations of the cation-anion pairs are randomly aligned, and when an electric field is applied between the first electrode  21  and the second electrode  22 , the orientations of the cation-anion pairs are aligned in a direction corresponding to the direction of the electric field. The entropy calculated when the orientations are randomly aligned is greater than the entropy calculated when the orientations are aligned, and the temperature observed when the orientations are randomly aligned is lower than when the temperature observed when the orientations are aligned. Thus, the ionic liquid  50  exhibits the electrocaloric effect, similarly with the ferroelectric. 
     The movable electrode  40  is provided in the ionic liquid such that the movable electrode  40  is movable in the ionic liquid  50 . The movable electrode  40  is a plate electrode disposed, parallel to the first electrode  21  and the second electrode  22 , in the ionic liquid  50 .  FIG.  2    is a cross-sectional view illustrating the movable electrode. As illustrated in  FIG.  2   , the movable electrode  40  includes a conductive base material  41 . The base material  41  is formed as a plate. Multiple openings  41 A are formed in the base material  41 . An insulating film  42  covering the surface of the base material  41  is formed. The insulating film  42  also covers the inner wall surface of the opening  41 A. The movable electrode  40  has an opening  40 A, having the insulating film  42  as sidewalls, inside the opening  41 A. The insulating film  42  includes, for example, silicon oxide, aluminum oxide, silicon nitride, zirconium oxide, hafnium oxide, titanium oxide, strontium titanate, barium titanate, lead zirconate titanate, or calcium copper titanate. 
     The first spacer  31  is provided on the inner surface of the first wall  11  and prevents the movable electrode  40  from contacting the first wall  11 . The second spacer  32  is provided on the inner surface of the second wall  12  and prevents the movable electrode  40  from contacting the second wall  12 . The first spacer  31  and the second spacer  32  are, for example, composed of insulators. In the first embodiment, the first spacer  31  is higher than the second spacer  32 . 
     As illustrated in  FIG.  1   , the electrocaloric effect element  1  is used while connected to a direct current power supply  60 . The negative electrode of the power supply  60  is connected to a ground terminal GND via a switch SW1. A node is provided between the negative electrode of the power supply  60  and the switch SW1, and a switch SW2 is provided to switch between the first electrode  21  and the second electrode  22  as the connection destination of the node. The positive electrode of the power supply  60  is connected to the base material  41  of the movable electrode  40 . The positive electrode of the power supply  60  is connected to the first electrode  21  via a switch SW3 and is connected to the second electrode  22  via a switch SW4. 
     Here, the characteristic of the ionic liquid  50  will be described.  FIG.  3    is graphs indicating the thermodynamic cycle of the ionic liquid  50 .  FIG.  3    indicates the relationship between the entropy S and the temperature T on the left side, and indicates the relationship between the electric field strength E and the temperature T on the right side. 
     In a first state  101 , an electric field is not applied, the electric field strength E is 0, the entropy S is S1, and the temperature T is T1. In the first state  101 , the orientations of the cation-anion pairs are randomly aligned. 
     Subsequently, when an electric field having an electric field strength E of E 1  is applied, the state transitions to a second state  102 . When the electric field strength E becomes E 1 , the temperature T increases rapidly to temperature T 2 , but the orientations of the cation-anion pairs remain randomly aligned, and the entropy S remains S1. 
     When the application of the electric field having an electric field strength E of E 1  is maintained, as time passes, the orientations of the cation-anion pairs change such that the orientations are aligned with the direction of the electric field having an electric field strength E of E 1 , and the state transitions to a third state  103 . During the transition from the second state  102  to the third state  103 , the entropy S decreases from S 1  to S 3  and the temperature T decreases from T 2  to T 3 . A decrease in the temperature of the ionic liquid  50  indicates that the heat retained in the ionic liquid  50  is released. 
     Subsequently, when the application of the electric field is stopped, the state transitions to a fourth state  104 . When the electric field strength E becomes 0, the temperature T decreases rapidly to temperature T 4 , but the orientations of the cation-anion pairs remain aligned, and the entropy S remains S 3 . 
     When the state in which the application of the electric field is stopped is maintained, as time passes, the orientations of the cation-anion pairs become randomly aligned and the state transitions to the first state  101 . During the transition from the fourth state  104  to the first state  101 , the entropy S increases from S 3  to S 1 , and the temperature T increases from T 4  to T 1 . An increase in the temperature of the ionic liquid  50  indicates that external heat is absorbed by the ionic liquid  50 . 
     The ionic liquid  50  has the characteristic described above. 
     Then, the electrocaloric effect element  1  according to the first embodiment operates as follows by utilizing such a characteristic.  FIGS.  4  to  10    are diagrams illustrating a cooling operation of the electrocaloric effect element  1  according to the first embodiment. This operation is achieved, for example, by a control mechanism, such as a computer, executing a control program. In  FIGS.  4  to  10   , the arrows in the ionic liquid  50  indicate the orientations of the cation-anion pairs. As illustrated in  FIGS.  4  to  10   , a heat source  72  to be cooled is provided on the second electrode  22  side and a heat sink  71  is provided on the first electrode  21  side. 
     First, as illustrated in  FIG.  4   , the switches SW1 and SW3 are closed, and the switches SW2 and SW4 are opened. Because the identical electric potential is applied to the first electrode  21  and the movable electrode  40 , the electric field strength E between the first electrode  21  and the movable electrode  40  is 0. Additionally, a repulsion force acts between the first electrode  21  and the movable electrode  40 , and the movable electrode  40  approaches the second electrode  22 , contacts the second spacer  32 , and stops. The potential of the second electrode  22  is floating and no electric field is applied between the second electrode  22  and the movable electrode  40 . In  FIG.  4   , all of the ionic liquid  50  is in the first state  101 . The entropy S is S 1  and the temperature T is T 1 . 
     Subsequently, as illustrated in  FIG.  5   , the switches SW1, SW3, and SW4 are opened, and the switch SW2 is connected to the first electrode  21  side. Because a voltage of the power supply  60  is applied between the first electrode  21  and the movable electrode  40 , an electric field having an electric field strength E of E 1  is applied between the first electrode  21  and the movable electrode  40 . Additionally, an attractive force acts between the first electrode  21  and the movable electrode  40 , and the movable electrode  40  approaches the first electrode  21 , contacts the first spacer  31 , and stops. At this time, the ionic liquid  50  is agitated through the opening  40 A. Therefore, heat transferred from the heat source  72  to the ionic liquid  50  is transferred from the ionic liquid  50  to the heat sink  71 , and is released to the outside from the heat sink  71 . A first portion  51  between the movable electrode  40  and the first electrode  21  in the ionic liquid  50  is in the second state  102 . That is, the entropy S remains S 1  and the temperature T increases to T 2 . In contrast, a second portion  52  between the movable electrode  40  and the second electrode  22  in the ionic liquid  50  remains in the first state  101 . 
     When the state of the switches SW1 to SW4 illustrated in  FIG.  5    is maintained, as illustrated in  FIG.  6   , as time passes, the orientations of the cation-anion pairs change in the first portion  51  such that the orientations are aligned with the direction of the electric field having an electric field strength E of E 1 . That is, the first portion  51  changes from the second state  102  to the third state  103 . At this time, the entropy S decreases from S 1  to S 3  and the temperature T decreases from T 2  to T 3 . Therefore, the heat is released from the first portion  51  to the heat sink  71 . Additionally, the second portion  52  remains in the first state  101 , but as the temperature of the first portion  51  decreases, the temperature difference between the first portion  51  and the heat source  72  increases, and the heat of the heat source  72  is transferred to the first portion  51  through the second portion  52 . 
     As time passes further, as illustrated in  FIG.  7   , the orientations of the cation-anion pairs in the first portion  51  are aligned in one direction, and the first portion  51  reaches the third state  103 . In the first portion  51 , the entropy S reaches S 3  and the temperature T reaches T 3 . The second portion  52  remains in the first state  101 , but as the temperature of the first portion  51  decreases, the temperature difference between the first portion  51  and the heat source  72  increases, and the heat of the heat source  72  is transferred to the first portion  51  through the second portion  52 . 
     Subsequently, as illustrated in  FIG.  8   , the switch SW1 is closed and the switches SW2, SW3 and SW4 are opened. Because the potentials of the first electrode  21 , the second electrode  22 , and the movable electrode  40  are floating, the electric field strength E of the electric field between the first electrode  21  and the movable electrode  40  and the electric field strength E between the second electrode  22  and the movable electrode  40  are both 0. The first portion  51  is in the fourth state  104 . That is, the entropy S remains S 3  and the temperature T decreases to T 4 . The second portion  52  remains in the first state  101 , but the heat of the heat source  72  is transferred to the first portion  51  through the second portion  52 . 
     When the state of the switches SW1 to SW4 illustrated in  FIG.  8    is maintained, as illustrated in  FIG.  9   , as time passes, the first portion  51  absorbs the heat from the second portion  52  and, in the first portion  51 , the orientations of the cation-anion pairs change to be randomly aligned. That is, the first portion  51  changes from the fourth state  104  to the first state  101 . At this time, the entropy S increases from S 3  to S 1 , and the temperature T increases from T 4  to T 1 . The second portion  52  remains in the first state  101 , but absorbs the heat from the heat source  72  because the heat is absorbed by the first portion  51 . 
     As time passes further, the orientations of the cation-anion pairs become randomly aligned in the first portion  51 , and the first portion  51  reaches the first state  101 . In the first portion  51 , the entropy S reaches S 1  and the temperature T reaches T 1 . The second portion  52  remains in the first state  101 , but the heat of the heat source  72  is transferred to the first portion  51  through the second portion  52 . 
     Subsequently, as illustrated in  FIG.  10   , the switches SW1 and SW3 are closed, and the switches SW2 and SW4 are opened. Because the identical electric potential is applied to the first electrode  21  and the movable electrode  40 , the electric field strength E of the electric field between the first electrode  21  and the movable electrode  40  is 0. Additionally, a repulsion force acts between the first electrode  21  and the movable electrode  40 , and the movable electrode  40  approaches the second electrode  22 , contacts the second spacer  32 , and stops. At this time, the ionic liquid  50  is agitated through the opening  40 A. Therefore, the heat transferred from the heat source  72  to the ionic liquid  50  is transferred from the ionic liquid  50  to the heat sink  71 , and is released to the outside from the heat sink  71 . As described, the state is returned to the state illustrated in  FIG.  4   . 
     As these cycles are repeated, the heat generated by the heat source  72  is transferred to the heat sink  71  by the electrocaloric effect element  1 . 
     According to the first embodiment, because the specific heat of the ionic liquid  50  is smaller than the specific heat of the ferroelectric material, the heat is transferred through the ionic liquid  50  itself in addition to the electrocaloric effect. Thus, the heat can be transferred efficiently and the heat source  72  can be cooled efficiently. 
     Additionally, if the movable electrode can move in the ionic liquid  50  having fluidity, the heat transfer is performed without deformation of the movable electrode  40 . Therefore, even if the shape of the electrocaloric effect element  1  is complicated, excellent heat transfer efficiency can be easily obtained. Additionally, the size of the electrocaloric effect element  1  can be diversified. For example, the size may be suitable for cooling smartphones or suitable for heating and cooling in buildings. 
     Further, with the electrocaloric effect element  1  having flexibility, the electrocaloric effect element  1  can be easily adhered to the heat source  72 , and the heat can be transferred more efficiently. 
     Here, the electrocaloric effect element  1  can be used not only for simple cooling but also for cooling while controlling the temperature.  FIGS.  11  and  12    are diagrams illustrating a temperature control operation of the electrocaloric effect element  1  according to the first embodiment. This operation is also achieved, for example, by a control mechanism, such as a computer, executing a control program. In  FIGS.  11  and  12   , the arrows in the ionic liquid  50  indicate the orientations of the cation-anion pairs. 
     First, as illustrated in  FIG.  11   , the switch SW1 is closed, the switches SW3 and SW4 are opened, and the switch SW2 is connected to the second electrode  22  side. Because the voltage of the power supply  60  is applied between the second electrode  22  and the movable electrode  40 , an electric field having an electric field strength E of E 1  is applied between the second electrode  22  and the movable electrode  40 , and the temperature T increases to T 2  in the second portion  52 . 
     Additionally, an attractive force acts between the second electrode  22  and the movable electrode  40 , and the movable electrode  40  approaches the second electrode  22 , contacts the second spacer  32 , and stops. When the state of the switches SW1 to SW4 illustrated in  FIG.  11    is maintained, as time passes, the orientations of the cation-anion pairs in the second portion  52  change such that the orientations are aligned with the direction of the electric field having an electric field strength E of E 1 . 
     Subsequently, as illustrated in  FIG.  12   , the switches SW1 and SW4 are closed, and the switches SW2 and SW3 are opened. Because the identical electric potential is applied to the second electrode  22  and the movable electrode  40 , the electric field strength E of the electric field between the second electrode  22  and the movable electrode  40  is 0. Additionally, a repulsion force acts between the second electrode  22  and the movable electrode  40 , and the movable electrode  40  approaches the first electrode  21 , contacts the first spacer  31 , and stops. At this time, the ionic liquid  50  is agitated through the opening  40 A. 
     As described above, the temperature control can be performed by using the electrocaloric effect element  1 . 
     Second Embodiment 
     A second embodiment relates to an electrocaloric effect element suitable for heating.  FIGS.  13  to  19    are diagrams illustrating a heating operation of an electrocaloric effect element  2  according to the second embodiment. This operation is also achieved, for example, by a control mechanism, such as a computer, executing a control program. In  FIGS.  13  to  19   , the arrows in the ionic liquid  50  indicate the orientations of the cation-anion pairs. As illustrated in  FIGS.  13  to  19   , the heat sink  71  to be heated is provided on the second electrode  22  side, and the heat source  72  is provided on the first electrode  21  side. Here, in the electrocaloric effect element  2  according to the second embodiment, the second spacer  32  is higher than the first spacer  31 . The other configuration is substantially the same as that of the electrocaloric effect element  1  according to the first embodiment. 
     First, as illustrated in  FIG.  13   , the switches SW1 and SW4 are closed, and the switches SW2 and SW3 are opened. Because the identical electric potential is applied to the second electrode  22  and the movable electrode  40 , the electric field strength E of the electric field between the second electrode  22  and the movable electrode  40  is 0. Additionally, a repulsion force acts between the second electrode  22  and the movable electrode  40 , and the movable electrode  40  approaches the first electrode  21 , contacts the first spacer  31 , and stops. The electric potential of the first electrode  21  is floating, and no electric field is applied between the first electrode  21  and the movable electrode  40 . In  FIG.  13   , all of the ionic liquid  50  is in the first state  101 . That is, the entropy S is S 1  and the temperature T is T 1 . 
     Subsequently, as illustrated in  FIG.  14   , the switches SW1, SW3, and SW4 are opened, and the switch SW2 is connected to the second electrode  22  side. Because the voltage of the power supply  60  is applied between the second electrode  22  and the movable electrode  40 , an electric field having an electric field strength E of E 1  is applied between the second electrode  22  and the movable electrode  40 . Additionally, an attractive force acts between the second electrode  22  and the movable electrode  40 , the movable electrode  40  approaches the second electrode  22 , contacts the second spacer  32 , and stops. At this time, the ionic liquid  50  is agitated through the opening  40 A. Thus, the heat transferred from the heat source  72  to the ionic liquid  50  is transferred from the ionic liquid  50  to the heat sink  71  and supplied to the heat sink  71 . The second portion  52  between the movable electrode  40  and the second electrode  22  in the ionic liquid  50  is in the second state  102 . That is, the entropy S remains S 1  and the temperature T increases to T 2 . In contrast, the first portion  51  between the movable electrode  40  and the first electrode  21  in the ionic liquid  50  remains in the first state  101 . 
     When the state of the switches SW1 to SW4 illustrated in  FIG.  14    is maintained, as illustrated in  FIG.  15   , as time passes, the orientations of the cation-anion pairs change in the second portion  52  such that the orientations are aligned with the direction of the electric field having an electric field strength E of E 1 . That is, the second portion  52  changes from the second state  102  to the third state  103 . At this time, the entropy S decreases from S 1  to S 3 , and the temperature T decreases from T 2  to T 3 . Therefore, the heat is supplied from the second portion  52  to the heat sink  71 . Additionally, the first portion  51  remains in the first state  101 , but as the temperature of the second portion  52  decreases, the temperature difference between the second portion  52  and the heat source  72  increases, and the heat of the heat source  72  is transferred to the second portion  52  through the first portion  51 . 
     As time passes further, as illustrated in  FIG.  16   , the orientations of the cation-anion pairs are aligned in one direction in the second portion  52  and the second portion  52  reaches the fourth state  104 . In the second portion  52 , the entropy S reaches S 3  and the temperature T reaches T 3 . The first portion  51  remains in the first state  101 , but as the temperature of the second portion  52  decreases, the temperature difference between the second portion  52  and the heat source  72  increases, and the heat of the heat source  72  is transferred to the second portion  52  through the first portion  51 . 
     Subsequently, as illustrated in  FIG.  17   , the switch SW1 is closed, and the switches SW2, SW3, and SW4 are opened. Because the electric potentials of the first electrode  21 , the second electrode  22 , and the movable electrode  40  are floating, the electric field strength E of the electric field between the first electrode  21  and the movable electrode  40  and the electric field strength E between the second electrode  22  and the movable electrode  40  are both 0. The second portion  52  is in the fourth state  104 . That is, the entropy S remains S 3  and the temperature T decreases to T 4 . The first portion  51  remains in the first state  101 , but the heat of the heat source  72  is transferred to the second portion  52  through the first portion  51 . 
     When the state of the switches SW1 to SW4 illustrated in  FIG.  17    is maintained, as illustrated in  FIG.  18   , as time passes, the second portion  52  absorbs the heat from the first portion  51  and, in the second portion  52 , the orientations of the cation-anion pairs change to be randomly aligned. That is, the second portion  52  changes from the fourth state  104  to the first state  101 . At this time, the entropy S increases from S 3  to S 1 , and the temperature T increases from T 4  to T 1 . The first portion  51  remains in the first state  101 , but absorbs the heat from the heat source  72  because the heat is absorbed by the second portion  52 . 
     As time passes further, the orientations of the cation-anion pairs become randomly aligned in the second portion  52 , and the second portion  52  reaches the first state  101 . In the second portion  52 , the entropy S reaches S 1  and the temperature T reaches T 1 . The first portion  51  remains in the first state  101 , but the heat of the heat source  72  is transferred to the second portion  52  through the first portion  51 . 
     Subsequently, as illustrated in  FIG.  19   , the switches SW1 and SW4 are closed, and the switches SW2 and SW3 are opened. Because the identical electric potential is applied to the second electrode  22  and the movable electrode  40 , the electric field strength E of the electric field between the second electrode  22  and the movable electrode  40  is 0. Additionally, a repulsion force acts between the second electrode  22  and the movable electrode  40 , and the movable electrode  40  approaches the first electrode  21 , contacts the first spacer  31 , and stops. At this time, the ionic liquid  50  is agitated through the opening  40 A. Therefore, the heat transferred from the heat source  72  to the ionic liquid  50  is transferred from the ionic liquid  50  to the heat sink  71 . As described, the state is returned to the state illustrated in  FIG.  13   . 
     As these cycles are repeated, the heat absorbed by the heat source  72  is supplied to the heat sink  71  by the electrocaloric effect element  1 . 
     According to the second embodiment, the heat sink  71  can be heated efficiently. 
     Here, the electrocaloric effect element  2  can be used not only for simple heating but also for heating while controlling the temperature.  FIGS.  20  and  21    are diagrams illustrating the temperature control operation of the electrocaloric effect element  2  according to the second embodiment. This operation is also achieved, for example, by a control mechanism, such as a computer, executing a control program. In  FIGS.  20  and  21   , the arrows in the ionic liquid  50  indicate the orientations of the cation-anion pairs. 
     First, as illustrated in  FIG.  20   , the switch SW1 is closed, the switches SW3 and SW4 are opened, and the switch SW2 is connected to the first electrode  21  side. Because the voltage of the power supply  60  is applied between the first electrode  21  and the movable electrode  40 , an electric field having an electric field strength E of E 1  is applied between the second electrode  22  and the movable electrode  40 , and the temperature T increases to T 2  in the first portion  51 . Additionally, an attractive force acts between the first electrode  21  and the movable electrode  40 , and the movable electrode  40  approaches the first electrode  21 , contacts the first spacer  31 , and stops. When the state of the switches SW1 to SW4 illustrated in  FIG.  20    is maintained, as time passes, the orientations of the cation-anion pairs in the first portion  51  change such that the orientations are aligned with the direction of the electric field having an electric field strength E of E 1 . 
     Subsequently, as illustrated in  FIG.  21   , the switches SW1 and SW3 are closed, and the switches SW2 and SW4 are opened. Because the identical electric potential is applied to the first electrode  21  and the movable electrode  40 , the electric field strength E of the electric field between the first electrode  21  and the movable electrode  40  is 0. Additionally, a repulsion force acts between the first electrode  21  and the movable electrode  40 , and the movable electrode  40  approaches the second electrode  22 , contacts the second spacer  32 , and stops. At this time, the ionic liquid  50  is agitated through the opening  40 A. 
     As described, the temperature control can be performed by using the electrocaloric effect element  2 . 
     Here, as illustrated in  FIG.  22   , two electrocaloric effect elements  1  may be provided in series between the heat sink  71  and the heat source  72 . That is, a heat transfer device having two electrocaloric effect elements  1  stacked together may be configured. In this heat transfer device, the first wall  11  of one container  10  faces the second wall  12  of the other container  10  between two electrocaloric effect elements  1  adjacent in a stacking direction. In this case, the efficiency of the heat transfer can be further improved by shifting the operating cycles between the two electrocaloric effect elements  1  by half a period. Three or more electrocaloric effect elements  1  may be provided in series between the heat sink  71  and the heat source  72 . Similarly, two or more electrocaloric effect elements  2  may be provided in series between the heat sink  71  and the heat source  72 . 
     Additionally, multiple electrocaloric effect elements  1  or  2  may also be provided in parallel between the heat sink  71  and the heat source  72 . In this case, the heat transfer can be performed over a wide range by synchronizing the operating cycles of the electrocaloric effect elements  1  or  2 . 
     In the present disclosure, the shapes of the first electrode and the second electrode are not limited. For example, the first electrode and the second electrode may have a tubular shape. In this case, for example, one can be an outer tube and the other can be an inner tube, and heat exchange fluid can be caused to flow through the inner tube. 
     The electrocaloric effect element according to the present disclosure can be used in a semiconductor manufacturing device. For example, a wafer chuck of a semiconductor manufacturing device may be provided with an electrocaloric effect element so that the temperature of a wafer held in the wafer chuck can be controlled. The electrocaloric effect element may be used to control the temperature of the transfer device that transfers the wafer. The electrocaloric effect element may be used to control the temperature of a chemical solution used for etching or the like. The electrocaloric effect element may be used to control the temperature of gas used to process the wafer. 
     The electrocaloric effect element according to the present disclosure can also be used to cool electronic devices, such as smartphones and tablet terminals. The electrocaloric effect element can also be used for heating and cooling in constructions, such as homes, buildings, and the like. 
     Although the preferred embodiments have been described in detail above, various modifications and substitutions can be made to the above-described embodiments without being limited by the above-described embodiments and departing from the scope of the claims. 
     This application is based on and claims priority to Japanese Patent Application No. 2020-142661, filed on Aug. 26, 2020, and the entire contents of which are incorporated herein by reference. 
     DESCRIPTION OF REFERENCE SYMBOLS 
     
         
         
           
               1 ,  2  electrocaloric effect element 
               10  container 
               11 ,  12  wall 
               21 ,  22  electrode 
               23 ,  24  insulating film 
               31 ,  32  spacer 
               40  movable electrode 
               40 A opening 
               41  base material 
               41 A opening 
               42  insulating film 
               50  ionic liquid 
               71  heat sink 
               72  heat source