WO2007099279A1 - Thick and thin films for power generation and cooling - Google Patents

Thick and thin films for power generation and cooling Download PDF

Info

Publication number
WO2007099279A1
WO2007099279A1 PCT/GB2006/050400 GB2006050400W WO2007099279A1 WO 2007099279 A1 WO2007099279 A1 WO 2007099279A1 GB 2006050400 W GB2006050400 W GB 2006050400W WO 2007099279 A1 WO2007099279 A1 WO 2007099279A1
Authority
WO
WIPO (PCT)
Prior art keywords
atomic
working body
thin
pyroelectric
film element
Prior art date
Application number
PCT/GB2006/050400
Other languages
French (fr)
Inventor
Alexandr Mishchenko
Roger William Whatmore
Original Assignee
Alexandr Mishchenko
Roger William Whatmore
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB0604109A external-priority patent/GB2435683A/en
Priority claimed from GB0611204A external-priority patent/GB2438895A/en
Application filed by Alexandr Mishchenko, Roger William Whatmore filed Critical Alexandr Mishchenko
Publication of WO2007099279A1 publication Critical patent/WO2007099279A1/en

Links

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N15/00—Thermoelectric devices without a junction of dissimilar materials; Thermomagnetic devices, e.g. using the Nernst-Ettingshausen effect
    • H10N15/10—Thermoelectric devices using thermal change of the dielectric constant, e.g. working above and below the Curie point
    • H10N15/15—Thermoelectric active materials

Definitions

  • This invention relates to apparatus and methods for the use of thick and thin films of electrocaloric and pyroelectric material for cooling or refrigeration and for electrical power generation.
  • Pyroelectric materials are especially attractive for heat-to-electricity converters due to the high efficiency of the energy transfer process.
  • the pyroelectric effect can be described as an electrical current generated by a change of temperature of a pyroelectric material.
  • the pyroelectric effect is thermodynamically converse to the electrocaloric effect. Therefore materials with large electro caloric effects are attractive for heat-to- electricity converters.
  • a example multilayer structure of Pb(Sco . sTao . s)0 3 for electrocaloric cooling is described in L.Shebanovs, K.Borman, W.N. Lawless, and A.Kalvane. Ferroelectrics 273, 137 (2002).
  • a working body of a cooling or refrigeration device comprising at least one electrocaloric thin or thick film element and a control input for controlling said electrocaloric thin film element.
  • An electrocaloric thin film element has a thickness of less than 1 ⁇ m.
  • Preferably said thin film has a thickness of from 10 to 900 ran, more preferably from 50 to 500 run, e.g. 350 run.
  • An electrocaloric thick film element has a thickness of from 1 ⁇ m to 100 ⁇ m, preferably from 1 to 10 ⁇ m.
  • EC electrocaloric
  • Zr-rich Pb(Zr 5 Ti)O 3 (PZT) electrocaloric films are used, e.g. Zr-rich films containing from 15-25 atomic % Zr, e.g. 19 atomic %.
  • One preferred embodiment of such an electrocaloric thin film comprises up to 20 atomic % Pb, up to 19 atomic % Zr, up to 1 atomic % Ti and up to 60 atomic % O, e.g.
  • an electrocaloric film comprising Pb(Zro 95 Ti 0 O s)O 3
  • an electrocaloric thin or thick film comprises up to 15 atomic % Pb, up to 12 atomic % Zr, up to 5 atomic % Ti and up to 75 atomic % O.
  • the thin or thick films may be deposited by any suitable technique, e.g. by sol-gel deposition by a plasma laser deposition system, by a magnetron sputtering system or a chemical vapour deposition system.
  • a working body of a device to convert heat into electrical power comprising at least one pyroelectric thin or thick film element and an input for controlling said pyroelectric thin film element.
  • the input may be termed a control input but, as described later, in embodiments it may also serve as a power output; alternatively separate input/control and "output" electrode connections may be provided.
  • a pyroelectric thin film element has a thickness of less than 1 ⁇ m.
  • said thin film has a thickness of from 10 to 900 nm, more preferably from 50 to 500 nm, e.g. 350 nm.
  • a pyroelectric thick film element has a thickness of from 1 ⁇ m to 100 ⁇ m, preferably from 1 to 10 ⁇ m.
  • Zr-rich Pb(Zr 5 Ti)O 3 (PZT) pyroelectric firms are used, e.g. Zr-rich films containing from 10-20 atomic % Zr, e.g. 15 atomic %.
  • Zr-rich films containing from 10-20 atomic % Zr, e.g. 15 atomic %.
  • One preferred embodiment of such a pyroelectric thin film comprises up to 15 atomic % Pb, up to 12 atomic % Zr, up to 5 atomic % Ti and up to 75 atomic % O, e.g. a pyroelectric film comprising Pb(Zr 0 . 95 Tio,o 5 ) ⁇ 3 .
  • Pb(Mg 5 Nb)O 3 - PbTiO 3 (PMN-PT) pyroelectric films are used.
  • a pyroelectric thin film comprises up to 25 atomic % Pb 5 up to 10 atomic % Mg, up to 20 atomic % Nb, up to 5 atomic % Ti and up to 80 atomic % O, e.g. a pyroelectric film comprising 0.9 Pb(Mg 173 Nb 2 Z 3 )O 3 - 0.1 PbTiO 3
  • PbSco 5 Ta 0 5 O 3 pyroelectric films are used.
  • One preferred embodiment of such a pyroelectric thin film comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta and up to 70 atomic % O
  • a pyroelectric thin film comprises up to 30 atomic % Pb, up to 15 atomic % Sc 5 up to 15 atomic % Ta, up to 15 atomic % Nb, and up to 70 atomic % O
  • pyroelectric films of PbSco 5 Tao 5 O 3 with up to about 20 atomic % substitution of Sc ions by Co, Fe, Ni, or Mn; or with up to about 20 atomic % substitution of Sc and Ta ions by Co, Sb, Nb, Ti, or In, Ga, Zn, Y, V, Zr, Hf, or Sn are used.
  • a pyroelectric thin film comprise up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 15 atomic % Nb, and up to 70 atomic % O.
  • Other preferred embodiments of such a pyroelectric thm film comprise up to 30 atomic % Pb, up to 15 atomic % Sc 5 up to 15 atomic % Ta, up to 70 atomic % O; and up to 20 atomic % Co, up to 20 atomic % Fe, up to 20 atomic % Ni, up to 20 atomic % Mn, up to 20 atomic % Sb, up to 20 atomic % Nb, up to 20 atomic % Ti, up to 20 atomic % In, up to 20 atomic % Ga, up to 20 atomic % Zn, up to 20 atomic % Y, up to 20 atomic % V, up to 20 atomic % Zr, up to 20 atomic % Hf, or up to 20 20 atomic
  • Nb-doped Pb(Zr, Sn,Ti) ⁇ 3 pyroelectric thin and thick firm materials e.g. Pb 0 99sNbo oi(Zro 65Ti 0 35)099O 3 , Pbo 99Nb 0 02(Zr 0 43Sno 43 Tio 14)0 9s ⁇ 3 > Pbo 99Nb 0 02(Zr 0 455Sn 0 455Ti 0 09)09sO 3 , or Pbo 99 Nb 0 02(Zr 0 7 5 Sn 0 2 Ti 0 05 )09gO 3 , are used.
  • Pb 0 99sNbo oi(Zro 65Ti 0 35)099O 3 Pbo 99Nb 0 02(Zr 0 43Sno 43 Tio 14)0 9s ⁇ 3 > Pbo 99Nb 0 02(Zr 0 455Sn 0 455Ti 0 09)09sO 3
  • a pyroelectric thin film comprises up to 30 atomic % Pb, up to 1 atomic % Nb, up to 30 atomic % Zr, up to 20 atomic % Sn, up to 10 atomic % Ti, and up to 70 atomic % O
  • One preferred embodiment of such a pyroelectric thin film comprises up to 30 atomic % Pb, up to 10 atomic % Mg, up to 15 atomic % Nb, up to 20 atomic % Ti, up to 10 atomic % Sr and up to 70 atomic % O
  • the thin or thick films may be deposited by any suitable technique, e.g. by sol-gel deposition comprising a spin coating or dip coating technique, by a plasma laser deposition system, by a magnetron sputtering system or a chemical vapour deposition system.
  • the thin or thick films may be deposited on oxide electrodes, e.g. SrRuO 3 or IrO 2 .
  • oxide electrodes e.g. SrRuO 3 or IrO 2 .
  • One preferred example of an SrRuO 3 thin film comprises up to 25 atomic % Sr, up to 25 atomic % Ru, and up to 70 atomic % O, while one preferred example of an IrO 2 thin film comprises up to 35 atomic % Ir and up to 75 atomic % 0.
  • the invention provides a working body of a device for transferring heat from a heat source to a heat sink, the device including a thick or thin film element, the thick or thin film element comprising a material as described above in connection with either the cooling or the electrical power generation aspects of the invention.
  • the materials described above in relation to the working body of a cooling or refrigeration device may be employed in the working body of a device for transferring heat from a heat source or a heat sink, in particular for electrical power generation, and vice versa.
  • the features of the above-described preferred embodiments of both the cooling and electrical power generation aspects of the invention are also applicable to a working body of a device for transferring heat from a heat source to a heat sink for either cooling or electrical power generation.
  • Fig. 1 Electrical measurements of Pb(Zro 95 Ti O O s)O 3 films on cooling.
  • A -(D) Uncompensated polarisation P versus applied electric field £ at 10 kHz.
  • A lossy paraelectric behaviour at 280 0 C.
  • C-D Evidence for antiferroelectricity is seen below 190 0 C.
  • E Real part of the effective dielectric constant ⁇ and loss tangent tan ⁇ measured at 100 kHz.
  • FIG. 3 An example diagram for an elementary heat-to- electricity cycle based on the data for PbZro. 9 5Tio.05O3 from [28].
  • Fig. 6 Entropy - temperature (S - T) diagram for different values of an applied electric field for PbZro .95 Tio .05 Os. The total entropy is estimated (e.g. as described in [21]) using the data disclosed in [28].
  • the cycle A-B-C-D is an ideal Caraot cycle.
  • FIG. 8 An example working body of an electro caloric / pyroelectric device.
  • Fig. 9. shows an example electrocaloric cooling system.
  • Heat source in (1) is colder than the heat sink, or "environment” ( ⁇ s O ur ce ⁇ ? ⁇ nv). Heat source in (2) is hotter than the heat sink (2s 0U rce > ?E ⁇ v)-
  • a working cycle of (1) is clockwise on the S-T (entropy-temperature) diagram.
  • a working cycle of (2) is anticlockwise on the S-T diagram, as shown in Figure 6.
  • Useful work in (1) is cooling, i.e. pumping heat from a cooled body.
  • Useful work in (2) is generation of electricity.
  • the basic principle of cooling is that the temperature of the environment ( T Em ) is higher than the temperature of a heat source (7s 0Urce )-
  • the heat source in this case is e.g. a cooled body in a fridge, or cool air inside a room in the case of an air conditioner. Without cooling, 7s ou ,- ce rises due to heat leaks from the environment.
  • the heat flow in a fridge/cooling device/air conditioner is from Is 0111 Ce to T ⁇ m so in both kinds of devices the heat is transferred from a heat source from a heat sink.
  • the temperature of the environment for a cooler is not necessarily the conventional room temperature, also the temperature of the cooled body may be higher than the conventional room temperature.
  • the basic principle of electrical power generation is that the temperature of the environment (T E ⁇ V ) is lower than the temperature of a heat source (Tsourcc)-
  • a processor in a laptop (7s 0Urce ) is at e.g. 7O 0 C and the ambient temperature (T Env ) is e.g. 25 0 C;
  • a solar collector [Wilma] (7s 0U r ce ) is at e.g. 14O 0 C and the ambient temperature ( J ⁇ nv) is e.g. 25°C,
  • Cooling liquid in an automobile (Tsource) is at e.g.80°C and the ambient temperature (J ⁇ nv) is e.g. 25°C.
  • Electrocaloric properties of Zr-rich Pb(Zr 5 Ti)O 3 were investigated to provide an example of an electrocaloric thin film material for cooling applications. We considered that it was possible that thin films of PZT could show promising EC effects, as the converse effect of pyroelectricity is pronounced and forms the basis of infrared detectors (10). Both Zr-rich PZT and the more common compositions such as PbZro .52 Ti 0 , 4 s0 3 are used as capacitors due to their high dielectric constants (12), and also as high-strain actuators/transducers and prototype microelectromechanical systems due to their piezoelectric properties (11).
  • PZT sols were prepared from Sigma-Aldrich precursors. Pb(OAc) 2 '3H 2 O was dissolved in methanol and refluxed for 2 hours at 70 0 C. Separately, a mixture of acetic acid and methanol was added to a mixture OfZr(O 11 Pr) 4 and Ti(O 11 Bu) 4 and the resulting solution was stirred at room temperature for two hours. The Pb and Zr/Ti based solutions were mixed with a 20% excess of the former to compensate for Pb loss during sintering. After gentle stirring, the yellow solution obtained was passed through a 0.2 ⁇ m filter and stabilized by the addition of ethylene glycol.
  • Sols were spin-coated at 3000 rpm for 30 s onto Pt(11 l)/TiO x /SiO 2 /Si(100) substrates that had been rinsed with acetone and propanol. Layers of -70 run were obtained by pre-firing in air on a hotplate at 300 0 C for 60 s, and then further annealing on another hotplate at 650 0 C for 10 minutes. This procedure was repeated five times to obtain -350 nm films.
  • Film structure was determined by x-ray diffraction on a Philips diffractometer using Cu Ka radiation. ⁇ -2 ⁇ scans corresponded to a polycrystalline perovskite phase with no preferred orientations, and no traces of pyrochlore.
  • Pt top electrodes of diameter 0.2 mm were sputtered through a mechanical mask, and the bottom Pt electrode was contacted with silver dag at a substrate edge. The dielectric constant and loss tangent were measured using a HP 4192A Impedance Analyser at 100 kHz and 100 mV ac amplitude. Hysteresis measurements were carried out at 10 kHz using a Radiant Technologies Precision Premier workstation and a high temperature (280 0 C) probe station.
  • the temperature of the sample was controlled via feedback from a thermocouple, accurate to 0.3 0 C, in contact with the sample.
  • This invention is however not limited to the particular composition Pb(Zro .95 Tio . ⁇ 5 ) ⁇ 3 and thin films of other compositions can be used for cooling applications.
  • the electro caloric effect is a change of temperature due to the application/removal of an applied electric field.
  • the pyroelectric effect can be described as an electrical current generated by a temperature change.
  • Electrocaloric and pyroelectric effects are thermo dynamically converse. Assuming reversible thermodynamics, the electrocaloric temperature change AT caused by a change of an applied electric field from E ⁇ to £ 2 at a temperature T in a material with heat capacity C and density p can be estimated by
  • p F — is the pyroelectric coefficient at an electric field E
  • Thin films can withstand much higher electric fields than bulk materials, giving a high electrocaloric effect and pyroelectric energy output in thin films.
  • thin or thick pyroelectric films are deposited on oxide electrodes, e.g. on SrRuO 3 [21, 22] or IrO 2 [22] to improve the fatigue properties and/or increase the breakdown field which will allow the application of higher electric fields and thus obtain a larger energy output.
  • a number of bulk materials show electrocaloric properties[l, 2, 17, 32-36]. As shown in [28] thin film materials should show larger electrocaloric effects than bulk materials of the same or similar composition. Due to the reasons given above, thin and thick film materials of these compositions should also exhibit a large pyroelectric effect and can therefore be used in a working body of a device for the conversion of heat to electrical energy according to embodiments of the present invention.
  • an elementary cycle for heat-to-electricity converter comprises (see Fig. 3): • an increase of an applied electric field across the thin film from Ei to E 2 at the temperature Ti 0W , (path A-B in Fig. 3)
  • Crystalline entropy 5c r y_ t of a material at a temperature T can be estimated as
  • a cycle A'-D'-C'-B'-A' in Fig, 6 is an example working cycle of a cooling device.
  • a cycle A-B-C-D-A in Fig 6 is an example cycle of a device that generates electricity from waste heat.
  • the cycled are ideal Carnot cycles and are shown for an example only. Embodiments of the present invention are not limited to these particular cycles.
  • an electro caloric (EC) / pyroelectric working element comprises a pair of electrodes 300 (which provide a control input or, in the case of a device for generating power from heat, a power output), and a slab of electrocaloric or pyroelectric material 310.
  • an electrocaloric or pyroelectric element is a capacitor with an electrocaloric or pyroelectric material between its electrodes.
  • switch 320 and power source 330 can be omitted and heat flowing through the device generates a pyroelectric current across the electrodes.
  • a voltage can be applied across the two electrodes to enhance the pyroelectric energy output.
  • Control electronics for example as described in US4, 425,540 (hereby incorporated by reference in its entirety) are used in place of switch 320 and power source 330.
  • FIG. 5585136 1996, for example.
  • the figure is a schematic only and different geometry can be used, as well as different structures of the electrodes (e.g. a multilayer capacitor structure, similar to that described in M. Togashi. "Multilayer ceramic electronic device", US Patent No. 2003/0026059, 2003, for example; layers of electrocaloric material in the multilayer capacitor can be made with thin film deposition techniques, e.g. sol-gel as disclosed in D, A. Barrow, T.E. Petroff, and M. Sayer. "Method for producing thick ceramic films by a sol gel coating process", US patent No. 5585136, 1996, for example).
  • thin film deposition techniques e.g. sol-gel as disclosed in D, A. Barrow, T.E. Petroff, and M. Sayer.
  • a liquid or gaseous heat exchanger is pumped through the working electrocaloric elements 600.
  • the heat exchanger When the heat exchanger is pumped down from a heat sink, the voltage across the electrocaloric elements is switched off and they cool down due to the electrocaloric effect.
  • the heat exchanger gradually cools down along the way due to heat exchange with cooled electrocaloric elements. Then the heat exchanger takes some heat from the heat load and is therefore heated up. After that the heat exchanger is pumped upwards, and the voltage across the electrocaloric elements is turned on.
  • a voltage is applied across the two electrodes when the working element is at a low temperature.
  • the working material is then heated up by e.g. a heat exchange fluid/gas pumped from the hot end.
  • the rise in temperature of the working material generates an electrical current, collected in a control output of the device.
  • the voltage across the working elements is switched off when they are at a maximum temperatrure.
  • the current generated is collected by a control output.
  • the heat exchanger is gradually cooled down on the way to the cold end of the device. It then releases more heat at the cold end of the device, and is pumped back afterwards.
  • the pyroelectric working elements are cooled down by the cold heat exchanger, and the voltage across them is turned on.

Landscapes

  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)

Abstract

We describe a working body of a cooling system which comprises thin or thick electrocaloric films. We also describe a working body of a device for converting heat to electrical power which comprises at least one thick or thin pyroelectric film. In specific embodiments, the thin or thick films are deposited by sol-gel, plasma deposition system, magnetron sputtering system or a chemical vapour deposition system. In specific embodiments, the thin or thick films consist of essentially up to about 20 atomic % Pb, up to about 19 atomic % Zr, up to about 1 atomic % Ti and up to about 60 atomic % O.

Description

M&C Folio: WPP290640
Thick and Thin Films for Power Generation and Cooling
FIELD OF THE INVENTION
This invention relates to apparatus and methods for the use of thick and thin films of electrocaloric and pyroelectric material for cooling or refrigeration and for electrical power generation.
BACKGROUND TO THE INVENTION
There has been increasing interest in alternative, environmentally friendly technologies over the last decades. Firstly, in relation to cooling it is important to reduce greenhouse gases that are used heavily in domestic and industrial refrigeration. Also, higher current densities in integrated circuits will impose higher demands on cooling systems that cannot be exclusively met by the current fan-based solutions. The electrocaloric (EC) effect is a change in the temperature of a material upon the application or withdrawal of an electric field under adiabatic conditions. It generated great interest (1-4) in the 1960s-70s, but has not been exploited commercially as the reported EC effects were small [L. Shebanovs, K. Borman, W.N. Lawless, A. Kalvane, "Electrocaloric effect in some perovskite ferroelectric ceramics and multilayer capacitors", Ferroelectrics, 273, 137-142 (2002)]. For example, bulk bo.99Nbo,o2(Zro,75Sno,2oTio,o5)0.98θ3 shows the highest EC effect measured so far, with direct measurements giving a peak value of 2.5 K in 750 V (i).
Secondly, there has been increasing interest in technologies for generation of electrical power from waste heat over the last decades. Pyroelectric materials are especially attractive for heat-to-electricity converters due to the high efficiency of the energy transfer process. The pyroelectric effect can be described as an electrical current generated by a change of temperature of a pyroelectric material. The pyroelectric effect is thermodynamically converse to the electrocaloric effect. Therefore materials with large electro caloric effects are attractive for heat-to- electricity converters.
A prototype device that generates electrical energy from waste heat is described in US4,425,540 Olsen, hereby incorporated by reference. The device relied on bulk materials, e.g. Pb(Zr,Sn,Ti)O3 ceramic, and was impractical due to (i) a low value of the pyroelectric energy output and (U) a low value of the heat conductivity of bulk electrically insulating polycrystalline ceramic materials. Another device to convert waste heat into electrical energy is described in US6,528,898 Ikura et al. This relies on multilayers of pyroelectric polymers, e.g. P(VF2 - TrFE), and multilayers of bulk ceramic Pb(Zr1Sn1Ti)O3 compounds but the electrical energy output is that of bulk polymers and ceramic materials, and is low for practical applications. A example multilayer structure of Pb(Sco.sTao.s)03 for electrocaloric cooling is described in L.Shebanovs, K.Borman, W.N. Lawless, and A.Kalvane. Ferroelectrics 273, 137 (2002).
Further background material can be found in the inventor's patent applications WO2006/056809 filed 21 November 2005, and GB0613578.4 filed 10 July 2006, both hereby incorporated by reference in their entirety.
We will describe electrocaloric thick and thin film cooling technology. We will also describe techniques for using thick and thin films for heat-to-electricity conversion devices along with some particular material compositions especially interesting for heat- to-power converters.
SUMMARY OF THE INVENTION
Cooling
In a first aspect of the present invention, there is provided a working body of a cooling or refrigeration device comprising at least one electrocaloric thin or thick film element and a control input for controlling said electrocaloric thin film element. An electrocaloric thin film element has a thickness of less than 1 μm. Preferably said thin film has a thickness of from 10 to 900 ran, more preferably from 50 to 500 run, e.g. 350 run.
An electrocaloric thick film element has a thickness of from 1 μm to 100 μm, preferably from 1 to 10 μm.
Preferably, said working body has a peak electrocaloric effect of at least 0.3 K V"1, preferably at least 0.4 K V"1, e.g. 12 K in a maximum applied voltage of 25 V at TEC = 2260C. By employing films of the thickness defined above, it is possible to achieve much higher electrocaloric (EC) temperature changes than have previously been obtainable with prior art EC elements, e.g. the previous best results obtained (1) in bulk Pb099Nb002(Zr075Sn020Ti0 Os)O 98 O3 were 2.5 K in 750 V, i.e. 0.003 K V"1 at 7k: = 162oC.
In one preferred embodiment of the invention, Zr-rich Pb(Zr5Ti)O3 (PZT) electrocaloric films are used, e.g. Zr-rich films containing from 15-25 atomic % Zr, e.g. 19 atomic %. One preferred embodiment of such an electrocaloric thin film comprises up to 20 atomic % Pb, up to 19 atomic % Zr, up to 1 atomic % Ti and up to 60 atomic % O, e.g. an electrocaloric film comprising Pb(Zro 95Ti0 Os)O3 In another embodiment of the invention an electrocaloric thin or thick film comprises up to 15 atomic % Pb, up to 12 atomic % Zr, up to 5 atomic % Ti and up to 75 atomic % O.
The thin or thick films may be deposited by any suitable technique, e.g. by sol-gel deposition by a plasma laser deposition system, by a magnetron sputtering system or a chemical vapour deposition system.
Electrical Power Generation
In another aspect of the present invention, there is provided a working body of a device to convert heat into electrical power comprising at least one pyroelectric thin or thick film element and an input for controlling said pyroelectric thin film element. The input may be termed a control input but, as described later, in embodiments it may also serve as a power output; alternatively separate input/control and "output" electrode connections may be provided.
A pyroelectric thin film element has a thickness of less than 1 μm. Preferably said thin film has a thickness of from 10 to 900 nm, more preferably from 50 to 500 nm, e.g. 350 nm.
A pyroelectric thick film element has a thickness of from 1 μm to 100 μm, preferably from 1 to 10 μm.
In one preferred embodiment of the invention, Zr-rich Pb(Zr5Ti)O3 (PZT) pyroelectric firms are used, e.g. Zr-rich films containing from 10-20 atomic % Zr, e.g. 15 atomic %. One preferred embodiment of such a pyroelectric thin film comprises up to 15 atomic % Pb, up to 12 atomic % Zr, up to 5 atomic % Ti and up to 75 atomic % O, e.g. a pyroelectric film comprising Pb(Zr0.95Tio,o5)θ3.
In another embodiment of the present invention, Pb(Mg5Nb)O3 - PbTiO3 (PMN-PT) pyroelectric films are used. One preferred embodiment of such a pyroelectric thin film comprises up to 25 atomic % Pb5 up to 10 atomic % Mg, up to 20 atomic % Nb, up to 5 atomic % Ti and up to 80 atomic % O, e.g. a pyroelectric film comprising 0.9 Pb(Mg173Nb2Z3)O3 - 0.1 PbTiO3
In another embodiment of the invention, PbSco 5Ta0 5O3 pyroelectric films are used. One preferred embodiment of such a pyroelectric thin film comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta and up to 70 atomic % O
In another preferred embodiment of the invention,
(1-x) PbSco 5Ta0^O3 - x PbSc0 5Nb05O3 pyroelectric films are used, where x represents respective atomic percentages of respective portions of the material, and 0 < x < 0.5. One preferred embodiment of such a pyroelectric thin film comprises up to 30 atomic % Pb, up to 15 atomic % Sc5 up to 15 atomic % Ta, up to 15 atomic % Nb, and up to 70 atomic % O In another preferred embodiment of the invention, pyroelectric films of PbSco 5Tao 5O3 with up to about 20 atomic % substitution of Sc ions by Co, Fe, Ni, or Mn; or with up to about 20 atomic % substitution of Sc and Ta ions by Co, Sb, Nb, Ti, or In, Ga, Zn, Y, V, Zr, Hf, or Sn, are used. Another preferred embodiment of such a pyroelectric thin film comprise up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 15 atomic % Nb, and up to 70 atomic % O. Other preferred embodiments of such a pyroelectric thm film comprise up to 30 atomic % Pb, up to 15 atomic % Sc5 up to 15 atomic % Ta, up to 70 atomic % O; and up to 20 atomic % Co, up to 20 atomic % Fe, up to 20 atomic % Ni, up to 20 atomic % Mn, up to 20 atomic % Sb, up to 20 atomic % Nb, up to 20 atomic % Ti, up to 20 atomic % In, up to 20 atomic % Ga, up to 20 atomic % Zn, up to 20 atomic % Y, up to 20 atomic % V, up to 20 atomic % Zr, up to 20 atomic % Hf, or up to 20 atomic % Sn.
In another preferred embodiment of the invention, Nb-doped Pb(Zr, Sn,Ti)θ3 pyroelectric thin and thick firm materials, e.g. Pb099sNbo oi(Zro 65Ti035)099O3, Pbo 99Nb002(Zr043Sno 43Tio 14)0 9sθ3> Pbo 99Nb002(Zr0455Sn0455Ti009)09sO3, or Pbo 99Nb002(Zr075Sn0 2Ti0 05)09gO3, are used. One preferred embodiment of such a pyroelectric thin film comprises up to 30 atomic % Pb, up to 1 atomic % Nb, up to 30 atomic % Zr, up to 20 atomic % Sn, up to 10 atomic % Ti, and up to 70 atomic % O
In another preferred embodiment of the invention, pyroelectric films of (3(PbMgO 33Nb0 67O3) - 6(PbTiO3) - C(SrTiO3), where a, b and c represent respective atomic percentages of respective portions of the material and 0.3 < a < 0.9, 0.05 < b < 0.6, 0 < c < 0.15, are preferably used. One preferred embodiment of such a pyroelectric thin film comprises up to 30 atomic % Pb, up to 10 atomic % Mg, up to 15 atomic % Nb, up to 20 atomic % Ti, up to 10 atomic % Sr and up to 70 atomic % O
The thin or thick films may be deposited by any suitable technique, e.g. by sol-gel deposition comprising a spin coating or dip coating technique, by a plasma laser deposition system, by a magnetron sputtering system or a chemical vapour deposition system. The thin or thick films may be deposited on oxide electrodes, e.g. SrRuO3 or IrO2. One preferred example of an SrRuO3 thin film comprises up to 25 atomic % Sr, up to 25 atomic % Ru, and up to 70 atomic % O, while one preferred example of an IrO2 thin film comprises up to 35 atomic % Ir and up to 75 atomic % 0.
All the materials described above, and all those described later can, potentially, be used in both cooling devices and in devices to generate electricity from heat such as waste heat.
Thus in a further aspect the invention provides a working body of a device for transferring heat from a heat source to a heat sink, the device including a thick or thin film element, the thick or thin film element comprising a material as described above in connection with either the cooling or the electrical power generation aspects of the invention.
Thus in embodiments of this aspect of the invention the materials described above in relation to the working body of a cooling or refrigeration device may be employed in the working body of a device for transferring heat from a heat source or a heat sink, in particular for electrical power generation, and vice versa. Further the features of the above-described preferred embodiments of both the cooling and electrical power generation aspects of the invention, such as film thicknesses and deposition techniques, are also applicable to a working body of a device for transferring heat from a heat source to a heat sink for either cooling or electrical power generation.
BRIEF DESCRIPTION OF THE FIGURES
Fig. 1. Electrical measurements of Pb(Zro 95TiO Os)O3 films on cooling. (A)-(D) Uncompensated polarisation P versus applied electric field £ at 10 kHz. (A) lossy paraelectric behaviour at 2800C. (B) The qualitative form of this hysteresis loop taken at 22O0C is unchanged through the ferroelectric to paraelectric transition at Tc =222°C. (C-D) Evidence for antiferroelectricity is seen below 1900C. (E) Real part of the effective dielectric constant ε and loss tangent tan ^measured at 100 kHz. A single peak is seen at the bulk phase transition temperature Jc = 222°C, but the antiferroelectric-ferroelectric transition cannot be resolved at lower temperatures. Extrapolation of the low temperature 1/f data gives Tc- = 242°C. (F) Leakage current measurements near the peak operating temperature TBc - 226°C (see Fig. 2). The figure is adapted from [28].
Fig. 2. Electro caloric temperature changes AT due to applied AE. Calculations were performed using Eq. 1 with selected values of AE = E2 - E1, where E2 = 776 kV cm"1. The peak value of Δ7>12 K occurs in ΔE = 480 kV cm"1 at TEC = 226°C where \dP/dT\ is maximised. Inset: P(T) at selected applied fields E. The lines represent 4{1 order polynomial fits to data extracted from the upper branches of nineteen hysteresis loops in E > 0. Four of the 19 loops are shown in Fig. IA-D. ). The figure is adapted from [28],
Fig. 3. An example diagram for an elementary heat-to- electricity cycle based on the data for PbZro.95Tio.05O3 from [28].
Fig. 4. Energy gained per one elementary cycle in Fig. 1 exceeds the best result so far [29] by a factor of 10. Hysteresis loss is around 20% as estimated form the area of the hysteresis loop at 2200C [28].
Fig. 5. Energy gained per one elementary cycle for three values AT.
Fig. 6. Entropy - temperature (S - T) diagram for different values of an applied electric field for PbZro.95Tio.05Os. The total entropy is estimated (e.g. as described in [21]) using the data disclosed in [28]. The cycle A-B-C-D is an ideal Caraot cycle.
Fig. 7. Example materials and suitable temperature ranges.
Fig. 8. An example working body of an electro caloric / pyroelectric device.
Fig. 9. shows an example electrocaloric cooling system. DETAILED DESCRIPTION QF PREFERRED EMBODIMENTS
We first describe some broad principles for a working body of a device that transfers heat from a heat source to a heat sink. Consider a cooling or refrigeration device (1) such as a fridge or air conditioner, and a device that generates electricity from heat (2) for example waste heat. Differences between (1) and (2) are:
• Heat source in (1) is colder than the heat sink, or "environment" (ϊsOurce <?Εnv). Heat source in (2) is hotter than the heat sink (2s0Urce>?Eτιv)-
• A working cycle of (1) is clockwise on the S-T (entropy-temperature) diagram. A working cycle of (2) is anticlockwise on the S-T diagram, as shown in Figure 6.
• Useful work in (1) is cooling, i.e. pumping heat from a cooled body. Useful work in (2) is generation of electricity.
The basic principle of cooling is that the temperature of the environment ( TEm) is higher than the temperature of a heat source (7s0Urce)- The heat source in this case is e.g. a cooled body in a fridge, or cool air inside a room in the case of an air conditioner. Without cooling, 7sou,-ce rises due to heat leaks from the environment.
Examples:
(i) domestic fridge is at e.g. Source = 5°C, and the environment is at e.g. 25°C. (ii) air conditioner in e.g. Australia on a hot sunny day: 7sOurcc = 200C, TEHV = 4O0C.
The heat flow in a fridge/cooling device/air conditioner is from Is0111Ce to T^m so in both kinds of devices the heat is transferred from a heat source from a heat sink. The temperature of the environment for a cooler is not necessarily the conventional room temperature, also the temperature of the cooled body may be higher than the conventional room temperature.
The basic principle of electrical power generation is that the temperature of the environment (TEΠV) is lower than the temperature of a heat source (Tsourcc)-
Examples:
(i) A processor in a laptop (7s0Urce) is at e.g. 7O0C and the ambient temperature (TEnv) is e.g. 250C; (U) A solar collector [Wilma] (7s0Urce) is at e.g. 14O0C and the ambient temperature ( JΕnv) is e.g. 25°C, (Ui) Cooling liquid in an automobile (Tsource) is at e.g.80°C and the ambient temperature (JΕnv) is e.g. 25°C. (iv) The ambient temperature (7EΠV) is below the standard room temperature (e.g. -100C in winter in northern USA), and the cooling liquid in an automobile is at e.g. Source = 4O0C.
The example (Zv) above illustrates that materials with working temperatures at or below room temperature can also be used in devices that generate electricity from heat (e.g. waste heat). All that is required for such a device is a heat flow from a heat source to the environment regardless of their temperatures given that Tsomce > T^m, Heat flow in a device that converts heat (e.g. waste heat) into electricity is from Isource
Thus the same materials can be used for cooling and generation of electricity from waste heat, depending on the application (as shown in the examples above).
Cooling
Electrocaloric properties of Zr-rich Pb(Zr5Ti)O3 (PZT) were investigated to provide an example of an electrocaloric thin film material for cooling applications. We considered that it was possible that thin films of PZT could show promising EC effects, as the converse effect of pyroelectricity is pronounced and forms the basis of infrared detectors (10). Both Zr-rich PZT and the more common compositions such as PbZro.52Ti0,4s03 are used as capacitors due to their high dielectric constants (12), and also as high-strain actuators/transducers and prototype microelectromechanical systems due to their piezoelectric properties (11).
Bulk Pb(Zro.95Tio.o5)C>3 is an orthorombic antiferro electric at room temperature. On heating to ~120°C, this structure transforms to a rhombohedral ferroelectric phase. There is substantial thermal hysteresis in this antiferro electric to ferroelectric transition, which on cooling occurs at ~80°C. The structure transforms to cubic paraelectric above 242°C. This is a first-order phase transition witli a Curie temperature, extrapolated linearly from the inverse dielectric susceptibility, of T0 = 225°C (12). The rhombohedal to paraelectric transition at this composition is close to a tricritical point at PbZro.94Tio.00O3 where its character changes from first to second order (73). These transition temperatures, which were taken from single crystals and high purity ceramics, differ somewhat from much earlier data (14), in which the sample purity was not as good. The EC effect could not be predicted from the literature, as there is no data for Zr-rich PZT thin films at the high temperatures and high electric fields of interest.
Description of an example cooling experiment
PZT sols were prepared from Sigma-Aldrich precursors. Pb(OAc)2'3H2O was dissolved in methanol and refluxed for 2 hours at 700C. Separately, a mixture of acetic acid and methanol was added to a mixture OfZr(O11Pr)4 and Ti(O11Bu)4 and the resulting solution was stirred at room temperature for two hours. The Pb and Zr/Ti based solutions were mixed with a 20% excess of the former to compensate for Pb loss during sintering. After gentle stirring, the yellow solution obtained was passed through a 0.2 μm filter and stabilized by the addition of ethylene glycol.
Sols were spin-coated at 3000 rpm for 30 s onto Pt(11 l)/TiOx/SiO2/Si(100) substrates that had been rinsed with acetone and propanol. Layers of -70 run were obtained by pre-firing in air on a hotplate at 3000C for 60 s, and then further annealing on another hotplate at 6500C for 10 minutes. This procedure was repeated five times to obtain -350 nm films.
Film structure was determined by x-ray diffraction on a Philips diffractometer using Cu Ka radiation. Θ-2Θ scans corresponded to a polycrystalline perovskite phase with no preferred orientations, and no traces of pyrochlore. Pt top electrodes of diameter 0.2 mm were sputtered through a mechanical mask, and the bottom Pt electrode was contacted with silver dag at a substrate edge. The dielectric constant and loss tangent were measured using a HP 4192A Impedance Analyser at 100 kHz and 100 mV ac amplitude. Hysteresis measurements were carried out at 10 kHz using a Radiant Technologies Precision Premier workstation and a high temperature (2800C) probe station. Leakage current was measured on the same workstation at 2200C under maximum applied voltage of 25 V (E = 776 kV cm"1). The temperature of the sample was controlled via feedback from a thermocouple, accurate to 0.30C, in contact with the sample.
Electrical hysteresis measurements were made roughly every 150C in the temperature range 35-2800C, on cooling to minimise reductions in P due to fatigue. Representative plots of P(E) are shown in Figs. IA-D. The dielectric constant ε and loss tangent, measured every 1°C on cooling, each show a broad peak associated with the ferroelectric-paraelectric transition at Tc = 2220C (Fig. IE), but no peaks corresponding to the antiferroelectric-ferroelectric transition can be resolved. This broadness is typical of thin films and is likely due to interfacial strain, scalar concentration gradients, or other forms of microscopic variability {IS), Extrapolation of the low temperature l/^data to zero gives TQ> - 242°C corresponding to the bulk value (72).
Reversible adiabatic changes in temperature AT for a material of density p with heat capacity C are given (1 T) by:
Figure imgf000012_0001
assuming the Maxwell relation (dP/dT)ir(dS/dE)τ. Values of dP/dT were obtained from 4th order polynomial fits to P(T) data (inset, Fig. 2) extracted from P(E). Fatigue may only reduce our values of \dP/dT\ since the data were taken on cooling such that P increased in successive hysteresis measurements, hi the temperature range of interest, the heat capacity 0=330 J K"1 kg"1 remains constant for Zr rich PZT films, and the peak associated with the transition is <10% of the background (18, 19). We note that assuming a constant value of C despite a -50% peak (77) resulted in excellent agreement with direct EC measurements of AT in bulk Pb0 99Nb01O2(Zr(X75Sn0 2oTio os)o 9gO3 (7). A value of/? = 8.3 g cm"3 reported for the similar compound (Pb,Zr,Sn)Tiθ3 was used here (77). The lower integration limit E1 = 295 kV cm"1 was set deliberately high to avoid the antiferroelectric regime (at low fields, Figs. IA-B), which ensures that dP/dT<0. The upper integration limit E2 — 776 kV cm"1 represents the maximum field at which a consistent dataset could be obtained.
EC temperature changes obtained via Eq. 1 are presented in Fig. 2, where the peak change (12 K in a maximum applied voltage of 25 V, i.e. 0.48 K V" ) at rEc = 226°C exceeds the previous best results obtained (7) in bulk Pb0 99Nbo.o2(Zro.75Sn0 20Ti0 O5)O98O3 (2.5 K in 750 V, i.e. 0.003 K V"1) at rEC = 162°C. By resorting to a thin film geometry we were able to apply electric fields that exceed bulk breakdown fields (-50 kV cm"1) by an order of magnitude (20). Indeed, our maximum field change (E2-Ei =480 kV cm"1) is sixteen times larger than the 30 kV cm"1 applied in (7). However, the relevant figure of merit for applications depends on the external voltage applied rather than the internal field generated. Note that films also offer a wide range of possible working temperatures (Fig. 2) associated with the broad phase transitions that they display (Fig. IE).
The use of reversible thermodynamics (Eq. 1) to determine the above result is justified in view of the relatively small hysteresis losses. Our peak EC temperature change of Δr=12 K, determined with Ei = 295 kV cm"1 and E2 = 776 kV cm"1, represents a peak energy change CAT= 4.02 IcJ kg"1. The corresponding hysteresis loss was 4% of this figure, as determined from the area of the 2200C hysteresis loop taken near the peak TEC = 226°C (Fig. IB) between the same values of E\ and E^. Therefore hysteresis losses have the potential to reduce our peak EC temperature change by only -0.5 K.
Leakage currents were investigated near the peak EC temperature in the maximum field employed (Fig. IF). The observed transients persist up to 200 ms, beyond which breakdown occurs. Therefore our figure of 50 nA is an upper bound for the steady state leakage current. This value yields negligible Joule heating (~10~3 K), and does not affect P(E) as currents of hundreds of μA are required to switch the measured polarizations at 10 IcHz,
There is further scope for optimising EC effects. For theoretical insights in respect of the models {5-7) discussed earlier it will be necessary to avoid the broad transitions seen in films, e.g. by nanopatterning single crystals (16). The following represent various possible materials improvements. Firstly, the use of oxide electrode such as SrRuO3 could increase breakdown fields and reduce fatigue (21, 22). Secondly, aliovalent doping with e.g. A-site La3+ or B-site Mn3+ may improve fatigue properties (10, 23). Thirdly, the partial substitution of Sn for Zr (1) or Sr for Pb (24) may lower TEC towards room temperature. Fourthly, the development of ferroelectric s that contain Bi rather than toxic Pb is an active area of research that could be relevant (25). Lastly, the introduction of crystallo graphic texture is desirable because materials of interest are anisotropic, and low angle grain boundaries enhance thermal conductivity.
This invention is however not limited to the particular composition Pb(Zro.95Tio.θ5)θ3 and thin films of other compositions can be used for cooling applications.
Power generation
The electro caloric effect is a change of temperature due to the application/removal of an applied electric field. The pyroelectric effect can be described as an electrical current generated by a temperature change. Electrocaloric and pyroelectric effects are thermo dynamically converse. Assuming reversible thermodynamics, the electrocaloric temperature change AT caused by a change of an applied electric field from E\ to £2 at a temperature T in a material with heat capacity C and density p can be estimated by
Figure imgf000015_0001
where pF = — is the pyroelectric coefficient at an electric field E, and a
reversible thermodynamic process is assumed. Therefore materials with good pyroelectric properties are likely to show good electrocaloric properties and vice versa.
Various bulk materials exhibiting the pyroelectric effect were considered as working bodies for heat-to-electricity converters [29-31]. The inherent efficiency of the heat-to- electricity conversion by means of the pyroelectric effect in bulk materials is up to 90% [29] of the maximum achievable (Carnot cycle) efficiency. A power generator based on the pyroelectric effect can be implemented in industrial plants, automobiles, solar power generation systems, etc. It can also be easily scaled down to recover electrical power from waste heat in electronic components in laptops, etc.
Some key facts about thin films of the present invention for heat-to-electricity converters:
• Thin films can withstand much higher electric fields than bulk materials, giving a high electrocaloric effect and pyroelectric energy output in thin films.
• The electrocaloric effect in bulk materials has been studied extensively in the past decades, but the effects were low and made the electrocaloric effect impractical due to the low electric fields that had to be applied.
• The electrocaloric and pyroelectric effects in thin films are large over a wide temperature range (e.g. 50-1000C around the peak temperature for PZT [28]). It makes thin films especially attractive for use in devices for the generation of electrical power from waste heat.
• Large electro caloric and pyroelectric effects are associated with phase transitions. Based on literature data, the transition temperature in already known thin films can be shifted by doping/substitution to cover the working temperature range from -500C to 3000C.
• Large cooling power and energy output per one working element can be achieved by producing thicker films and/or multilayer ed structures.
In some embodiments of the present invention, thin or thick pyroelectric films are deposited on oxide electrodes, e.g. on SrRuO3 [21, 22] or IrO2 [22] to improve the fatigue properties and/or increase the breakdown field which will allow the application of higher electric fields and thus obtain a larger energy output.
A number of bulk materials show electrocaloric properties[l, 2, 17, 32-36]. As shown in [28] thin film materials should show larger electrocaloric effects than bulk materials of the same or similar composition. Due to the reasons given above, thin and thick film materials of these compositions should also exhibit a large pyroelectric effect and can therefore be used in a working body of a device for the conversion of heat to electrical energy according to embodiments of the present invention.
Description of an example electrical power generation experiment
A giant electrocaloric effect in thin film Zr-rich Pb(Zr5Ti)O3 (PZT) was reported in [28]. The effect is associated with the paraelectric-to-ferroelectric phase transition in PZT. The experimental data used for [28] can also be used to estimate the performance of PZT for heat-to-electricity energy converters as shown below.
Plots of polarisation versus electric field in Zr-rich PZT at Tcoid = 1900C and T1 HOt = 2400C are shown in Fig. 3. In one embodiment of the present invention, an elementary cycle for heat-to-electricity converter comprises (see Fig. 3): • an increase of an applied electric field across the thin film from Ei to E2 at the temperature Ti 0W, (path A-B in Fig. 3)
• heating the thin film to the temperature 7Ηigh with the field E2 still applied (path B-C in Fig. 3) and collecting the electrical current due to the pyroelectric effect associated with heating,
• a decrease of an applied electric field from E2 to Ei at the temperature JΗigh (path C-D in Fig. 3), and
• cooling the film to the temperature 2LOW with the electric field Ei still applied (path D-A in Fig. 3).
The electrical energy (per 1 cm3) w gained in one elementary cycle described above can be estimated as
Figure imgf000017_0001
where P is polarisation and E is an applied electric field. In other words, w is the area bounded by the contour ABCD in Fig. 3. Among other parameters, the energy w gained per one cycle depends on the temperature difference AT = 7Ηigh - 7L0W! and on the average temperature TAV& ~ 0.5(7Ηigh-7Low)> as shown in Figs. 4 and 5. The energy output of Zr-rich PZT films shown in the figures exceeds the results reported in literature [29-31J by at least a factor of 10. This enhancement is due to the fact that thin films have much higher breakdown fields than the bulk materials used in prior art documents such as [29], and Zr-rich PZT films have much higher polarisation values than the polymers used in prior art documents such as [31].
Crystalline entropy 5cry_t of a material at a temperature T can be estimated as
Figure imgf000017_0002
where C is the heat capacity of the material. A change of an applied electric field from Ei to E2 induces a change ASo\v of the entropy of the system of electrical dipoles of the material according to
Figure imgf000017_0003
where P is polarisation and E\ and E2 were explained above. The total entropy of a material is therefore
S — Sciyst + ΔjSoip
An ideal (Carnot) thermodynamic cycle for a heat-to-electricity converter of the present example experiment is shown in Fig. 6 in S- T variables, where S is the total entropy, and T is the temperature of Zr-rich PZT thin films from [28]. This cycle is well known for people acquainted with the field. The Carnot cycle is different from that discussed above and illustrated in Fig. 3. Indeed, the Carnot cycle requires increase of the temperature of a material from JLOW to Tn\φ (path B-C in Fig. 6) under adiabatic conditions, which involves increasing an applied electric field at the same time. The Carnot cycle is the most efficient, although impractical due to an infinitely long time of heat exchange along pathes A-B and C-D (Fig. 6). It is important to note that the present invention is not limited to any of the thermodynamic cycles described. They are shown for an example only.
A cycle A'-D'-C'-B'-A' in Fig, 6 is an example working cycle of a cooling device. A cycle A-B-C-D-A in Fig 6 is an example cycle of a device that generates electricity from waste heat. The cycled are ideal Carnot cycles and are shown for an example only. Embodiments of the present invention are not limited to these particular cycles.
Again, all the above-described materials can be used for cooling and power generation depending on the application, as shown in Figure 7.
An example geometry of an electro caloric (EC) / pyroelectric working element is shown in Fig. 8. It comprises a pair of electrodes 300 (which provide a control input or, in the case of a device for generating power from heat, a power output), and a slab of electrocaloric or pyroelectric material 310. Broadly speaking, an electrocaloric or pyroelectric element is a capacitor with an electrocaloric or pyroelectric material between its electrodes. In the case of a pyroelectric device switch 320 and power source 330 can be omitted and heat flowing through the device generates a pyroelectric current across the electrodes. In simplified terms a voltage can be applied across the two electrodes to enhance the pyroelectric energy output. A change in temperature of the working body, results in a current flowing through the electrodes. The cycle then repeats. Control electronics, for example as described in US4, 425,540 (hereby incorporated by reference in its entirety) are used in place of switch 320 and power source 330.
It should be understood that the figure is a schematic only and different geometry can be used, as well as different structures of the electrodes (e.g. a multilayer capacitor structure, similar to that described in M. Togashi. "Multilayer ceramic electronic device", US Patent No. 2003/0026059, 2003, for example; layers of electrocaloric material in the multilayer capacitor can be made with thin film deposition techniques, e.g. sol-gel as disclosed in D, A. Barrow, T.E. Petroff, and M. Sayer. "Method for producing thick ceramic films by a sol gel coating process", US patent No. 5585136, 1996, for example).
The principle of operation of an example cooling device is described in Y.V.Sinyavsky and V.M.Brodyansky. Ferro electrics 131, 321 (1992). Referring to Figure 9, a liquid or gaseous heat exchanger is pumped through the working electrocaloric elements 600. Let us consider the right stack 600. When the heat exchanger is pumped down from a heat sink, the voltage across the electrocaloric elements is switched off and they cool down due to the electrocaloric effect. The heat exchanger gradually cools down along the way due to heat exchange with cooled electrocaloric elements. Then the heat exchanger takes some heat from the heat load and is therefore heated up. After that the heat exchanger is pumped upwards, and the voltage across the electrocaloric elements is turned on. Their temperature rises due to the electrocaloric effect, and the heat exchanger is gradually heated on the way up before it releases some heat to the heat sink. The cycle is completed at this stage and is repeated for continuous operation. Thin or thick electrocaloric elements according to embodiments of the present invention show a much larger electrocaloric effect, and faster heat exchange with the heat exchanger and therefore larger cooling power and efficiency than working elements described in Y.V.Sinyavsky and V.M.Brodyansky. Ferroelectrics 131, 321 (1992). In the case of a pyroelectric device the change in temperature of a pyroelectric working element generates an electric current flowing to/from its electrodes. More particularly in operation, as described in more detail above, broadly speaking a voltage is applied across the two electrodes when the working element is at a low temperature. The working material is then heated up by e.g. a heat exchange fluid/gas pumped from the hot end. The rise in temperature of the working material generates an electrical current, collected in a control output of the device. The voltage across the working elements is switched off when they are at a maximum temperatrure. The current generated is collected by a control output. The heat exchanger is gradually cooled down on the way to the cold end of the device. It then releases more heat at the cold end of the device, and is pumped back afterwards. The pyroelectric working elements are cooled down by the cold heat exchanger, and the voltage across them is turned on. The system is back to its initial state, and the cycle is complete. Some current is supplied to the working elements from the control input of the device. However the total electrical energy output exceeds the electrical energy input therefore the device generates electrical energy. Thin and thick films of the present invention show a much larger electrical energy output and faster heat exchange, which results in an increased power output and efficiency of the device compared to the prototype suggested in US4,425,540. This operation principle can also be implemented using a system of the type illustrated in Figure 9.
No doubt many other effective alternatives will occur to the skilled person. It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the spirit and scope of the claims appended hereto. REFERENCES
1. B.A. Tuttle, DA. Payne, Ferroelectrics 37, 603 (1981).
2. P.D. Thacher, J Appl. Phys. 39, 1996 (1968).
3. W.N. Lawless, Phys. Rev. B. 16, 433 (1977).
4. B.A. Strukov, Soviet Physics Crystallography 11, 757 (1967).
5. E. Fatuzzo, WJ. Merz, Ferroelectricity (North-Holland, Amsterdam, 1967).
6. T. Mitsui, Introduction to the Physics of Ferroelectricity (Gordon & Breach, London, 1976).
7. F. Jona, G. Shirane, Ferroelectric Crystals (McMillan, NY 1962).
8. R. Resta, Rev. Mod. Phys. 66, 899 (1994).
9. R. D. Kingsmith and D. Vanderbilt, Phys. Rev. B. 47, 1651 (1993).
10. Q. Zhang, R. W. Whatmore, J. Appl. Phys. 94, 5228 (2003).
11. W. Y. Pan, CQ. Dam, Q.M. Zhang, L.E. Cross, J. Appl. Phys. 66, 6014 (1989).
12. R.W. Whatmore, PIiD Thesis, Cambridge University (1977).
13. R.W. Whatmore, R. Clarke, A.M. Glazer, J Phys. C: Solid State Phys. 11, 3089 (1978).
14. E. Sawaguchi, J Phys. Soc. Japan 8, 615 (1953).
16. M.M. Saad et al., J. Phys.: Cond. Matt., 16, L451 (2004).
17. B.A. Tuttle, PhD Thesis, University of Illinois at Urbana - Champaign (1981).
18. S. T. Davitadze, PhD Thesis, Lomonosov Moscow State University (2003).
19. G. Suchanek et al, Mat. Res. Soc. Proc. 718, D8.4.1 (2002).
20. J.F. Scott, Ferroelectric Memories (Springer, Berlin, 2000), p.64,
21. U, Ellerkmann et al., Integrated Ferroelectrics. 52, 63 (2003).
22. K, Maki et al, Integrated Ferroelectrics . 52, 19 (2003).
23. Q. Zhang, J Phys. D. : Appl. Phys. 37, 98 (2004).
24. P.C. Osbond, R. W. Whatmore, Ferroelectrics. 118, 93 (1991).
25. D. Fu, K. Suzuki, K. Kato, Jpn. J. App. Phys. 41, L1103 (2002).
26. J.F. Nye, Physical Properties of Crystals (Oxford University Press, 2003), chap. X.
27. M.E. Lines and A.M. Glass, Principles and Applications of Ferroelectrics and Related Materials (Oxford University Press, Oxford, 1977), p. 149.
28. A.S. Mischenko Q. Zhang, J.F. Scott, R.W. Whatmore, and N.D. Mathur. Science 311, 1270 (2006). 29. R.B. Olsen and D. Evans. J. Appl. Phys. 54, 5491 (1983).
30. R.B. Olsen. US Patent No 4647836 (1987).
31. R.B. Olsen, D. A. Bruno, LM. Briscoe and E. W. Jacobs. J. Appl. Phys. 57, 5036 (1985).
32. E.H. Birks, L.A. Shebanov, K. Ya Bormanis, M. Ya. Dambekalne. SU Patent No. SU141479440 (1986).
33. L.A. Shebanov, E. H. Birks and KJ. Borman, Ferroelectrics 90, 165 (1989).
34. L.Shebanov and K. Borman, Ferroelectrics, 127, 143 (1992).
35. W.N. Lawless, US Patent US6877325 (2005).
36. L. Shaobo and L. Yanqiu, Mat. Sci. and Eng. 113, 46 (2004).
37. L. Shebanovs, K. Borman, W.N. Lawless, A. Kalvane, "Electro caloric effect in some perovskite ferroelectric ceramics and multilayer capacitors", Ferroelectrics, 273, 137-142 (2002).

Claims

1. Working body of a cooling device comprising at least one electro caloric thin or thick film element and a control input for controlling said electrocaloric thin or thick film element.
2. Working body of a device for converting of heat to electrical energy comprising at least one pyro electric thin or thick film element and a control input for controlling said pyroelectric thin or thick film element.
3. Working body as claimed in claim 1 or 2, wherein said thin or thick firm is deposited by sol-gel deposition.
4. Working body as claimed in claim 1 or 2, wherein said thin or thick film is deposited by a plasma laser deposition system.
5. Working body as claimed in claim 1 or 2, wherein said thin or thick film is deposited by a magnetron sputtering system.
6. Working body as claimed in claim 1 or 2, wherein said thin or thick film is deposited by a chemical vapour deposition system.
7. Working body as claimed in claim 1 or 2, wherein said thin or thick film is deposited by dip coating.
8. Working body as claimed in claim 1 or 2, wherein said thin or thick film is deposited by spin coating,
9. Working body as claimed in any one of claims 1 to 8, comprising at least one electrocaloric or pyroelectric thin film element.
10. Working body as claimed in claim 9, wherein said thin film element has a thickness of less than 1 μm.
11. Working body as claimed in claim 9, wherein said thin film element has a thickness of from 10 to 900 nm.
12. Working body as claimed in claim 9, wherein said thin film element has a thickness of from 50 to 500 nm.
13. Working body as claimed in any one of claims 1 to 8, comprising at least one electro caloric or pyroelectric thick film element.
14. Working body as claimed in claim 13, wherein said thick film element has a thickness of from 1 μm to 100 μm.
15. Working body as claimed in claim 13, wherein said thick film element has a thickness of from 1 to 10 μm.
16. Working body as claimed in any one of claims 1 and 3 to 15, when dependent on claim 1, wherein said working body has a peak electrocaloric effect of at least 0.3 K V"1.
17. Working body as claimed in any one of claims 1 and 3 to 15, when dependent on claim 1, wherein said working body has a peak electrocaloric effect of at least 0.4 K V1.
18. Working body as claimed in any one of claims 1 and 3 to 15, when dependent on claim I3 wherein said working body has a peak electrocaloric effect of at least 12 K in a maximum applied voltage of 25 V at T^c = 2260C.
19. Working body as claimed in any one of claims 1 to 15, wherein said at least one electrocaloric or pyroelectric thin or thick film element comprises a Zr-rich Pb(Zr, Ti)O3 (PZT) electrocaloric or pyroelectric film.
20. Working body as claimed in claim 19, wherein said Zr-rich Pb(Zr5Ti)O3 (PZT) electrocaloric or pyroelectric film contains from 15-25 atomic % Zr.
21. Working body as claimed in claim 19, wherein said at least one electrocaloric or pyroelectric thin or thick film element consists of essentially up to 25 atomic % Pb, up to 25 atomic % Zr, up to 2 atomic % Ti and up to 65 atomic % O.
22. Working body as claimed in claim 21, wherein said at least one electrocaloric or pyroelectric thin or thick film element comprises Pb(Zro.95Tio.o5)03.
23. Working body as claimed in any one of claims 1 to 8, wherein said electrocaloric or pyroelectric thin or thick film element is deposited on SrRuO3 thin film that consists of essentially up to 25 atomic % Sr, up to 25 atomic % Ru, and up to 70 atomic % O.
24. Working body as claimed in any one of claims 1 to 8, wherein said electrocaloric or pyroelectric thin or thick film element is deposited on IrO2 thin film that consists of essentially up to 35 atomic % Ir and up to 75 atomic % O.
25. Working body as claimed in any one of claims 1 to 8 and 23 to 24, comprising at least one electrocaloric or pyroelectric thin film element.
26. Working body as claimed in claim 25, wherein said pyroelectric thin film element has a thickness of less than 1 μm.
27. Working body as claimed in claim 25, wherein said pyroelectric thin film element has a thickness of from 10 to 900 nm.
28. Working body as claimed in claim 25, wherein said pyroelectric thin film element has a thickness of from 50 to 500 nm.
29. Working body as claimed in any one of claims 1 to 8 and 23 to 24, comprising at least one pyroelectric thick film element.
30. Working body as claimed in claim 29, wherein said pyroelectric thick film element has a thickness of from 1 μm to 100 μm.
31. Working body as claimed in claim 29, wherein said pyroelectric thick film element has a thickness of from 1 to 10 μm.
32. Working body as claimed in any one of claims 1 to 8 and 23 to 31, wherein said at least one pyroelectric thin or thick film element comprises a PbSco sTao 5O3 pyroelectric film.
33. Working body as claimed in claim 32, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta and up to 70 atomic % O
34. Working body as claimed in any one of claims 1 to 8 and 23 to 31, wherein said at least one pyroelectric thin or thick film element comprises a (I-*) PbSco.sTao 5O3 - x PbSco sNbo 5O3 pyroelectric film, wherein x represents the atomic proportions of the respective proportions of the material and 0 <x<0.5.
35. Working body as claimed in claim 34, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 15 atomic % Nb, and up to 70 atomic % O.
36. Working body as claimed in any one of claims 1 to 8 and 23 to 31 , wherein said at least one pyroelectric thin or thick firm element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 15 atomic % Nb, and up to
70 atomic % O.
37. Working body as claimed in any one of claims 1 to 8 and 23 to 31, wherein said at least one pyroelectric thin or thick firm element comprises a pyroelectric film of PbSco.5Tao.5O3 with up to 20 atomic % substitution of Sc ions by Co, Fe, Ni, or Mn.
38. Working body as claimed in claim 37, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Fe, and up to 70 atomic % O.
39. Working body as claimed in claim 37, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb1 up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Ni, and up to 70 atomic % O.
40. Working body as claimed in claim 37, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Mn, and up to 70 atomic % O.
41. Working body as claimed in any one of claims 1 to 8 and 23 to 31, wherein said at least one pyroelectric thin or thick film element comprises a pyroelectric film of PbSco.5Tao.5O3 with up to about 20 atomic % substitution of Sc and Ta ions by Co, Sb, Nb, Ti, In, Ga, Zn, Y, V, Zr, Hf, or Sn.
42. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Co, and up to 70 atomic % O.
43. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Sb, and up to 70 atomic % O.
44. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Nb, and up to 70 atomic % O.
45. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Ti, and up to 70 atomic % O.
46. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % In, and up to 70 atomic % O.
47. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Ga, and up to 70 atomic % O.
48. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Zn, and up to 70 atomic % O.
49. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Y, and up to 70 atomic % O.
50. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % V, and up to 70 atomic % O.
51. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Zr, and up to 70 atomic % O.
52. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Hf, and up to 70 atomic % O.
53. Working body as claimed in claim 41, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 20 atomic % Sn, and up to 70 atomic % O.
54. Working body as claimed in any one of claims 1 to 8 and 23 to 31, wherein said at least one pyroelectric thin or thick film element comprises a Nb-doped Pb(Zr,Sn,Ti)O3 pyroelectric film.
55. Working body as claimed in claim 54, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 1 atomic % Nb, up to 30 atomic % Zr, up to 20 atomic % Sn, up to 10 atomic % Ti, and up to 70 atomic % O.
56. Working body as claimed in claim 55, wherein said at least one pyroelectric thin or thick film element comprises Pbo 995Nb001(Zr0 65Tio 35)099O3.
57. Working body as claimed in claim 55, wherein said at least one pyroelectric thin or thick film element comprises Pbo 9gNbo o2(Zro 43Sno 43Η0 14)093O3.
58. Working body as claimed in claim 55, wherein said at least one pyroelectric thin or thick film element comprises Pbo 99Nbo o2(Zro 455Sn0 455Ti009)098O3.
59. Working body as claimed in claim 55, wherein said at least one pyroelectric thin or thick film element comprises Pb099Nb0 02(Zr0 75Sn02Tio os)09sO3.
60. Working body as claimed in any one of claims 1 to 8 and 23 to 31, wherein said at least one pyroelectric thin or thick film element comprises a
G(PbMg033Nb007O3) - 6(PbTiO3) - C(SrTiO3) electrocaloric film, where a, b and c represent respective atomic percentages of respective portions of said pyroelectric thin or thick film material.
61. Working body as claimed in claim 60, wherein a represents an atomic percentage of between 0 and 90, b represents an atomic percentage of between 0 and 60, and c represents an atomic percentage of between 0 and 15.
62. Working body as claimed in claim 60, wherein 0.3 < a < 0.9, 0.05 < b < 0.6 and 0 < c < 0.15.
63. Working body as claimed in claim 60, wherein said pyroelectric thin film comprises up to 30 atomic % Pb, up to 10 atomic % Mg, up to 15 atomic % Nb, up to 20 atomic % Ti, up to 10 atomic % Sr and up to 70 atomic % O
64. Working body as claimed in any one of claims 1 to 8 and 23 to 31, wherein said at least one pyroelectric thin or thick film element comprises a Zr-rich Pb(Zr5Ti)O3 (PZT) pyroelectric film.
65. Working body as claimed in claim 64, wherein said Zr-rich Pb(Zr5Ti)O3 (PZT) pyroelectric film contains from 15-25 atomic % Zr.
66. Working body as claimed in claim 64, wherein said at least one pyroelectric thin or thick film element comprises up to 15 atomic % Pb, up to 12 atomic % Zr, up to 5 atomic % Ti and up to 75 atomic % O.
67. Working body as claimed in claim 64, wherein said at least one pyroelectric thin or thick film element comprises up to 25 atomic % Pb5 up to 25 atomic % Zr, up to 2 atomic % Ti and up to 65 atomic % O.
68. Working body as claimed in claim 64, wherein said at least one pyroelectric thin or thick film element comprises Pb(Zro.95Tio O5)O3
69. Working body as claimed in any one of claims 1 to 8 and 23 to 31, wherein said at least one pyroelectric thin or thick film element comprises a Pb(Mg5Nb)O3-PbTiO3 pyroelectric film.
70. Working body as claimed in claim 69, wherein said at least one pyroelectric thin or thick film element comprises up to 25 atomic % Pb, up to 10 atomic % Mg, up to 20 atomic % Nb, up to 5 atomic % Ti and up to 80 atomic % O.
71. Working body as claimed in claim 69, wherein said at least one pyroelectric thin or thick film element comprises 0.9 Pb(Mgi/3Nb2/3)O3 - 0.1 PbTiO3
72. A working body of a device for transferring heat from a heat source to a heat sink, the device including a thin or thick film element, the thin or thick film element comprising a material as defined in any one of claims 19 to 24 and 32 to 71, not limited to a working body specifically for either cooling or converting heat to eletrical energy.
73. A method of cooling, the method comprising applying electrical power to the working body of a cooling device comprising at least one electrocaloric thin or thick film element and a control input for controlling said electrocaloric thin film element, in particular a working body as claimed in any preceding claim.
74. A method of generating electrical power from heat, the method comprising transferring heat from a heat source to a heat sink through a working body of a device comprising at least one pyroelectric thick or thin film element, in particular as claimed in any one of claims 1 to 72,
PCT/GB2006/050400 2006-03-01 2006-11-20 Thick and thin films for power generation and cooling WO2007099279A1 (en)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
GB0604109A GB2435683A (en) 2006-03-01 2006-03-01 Electrocaloric Film for a Cooling Device
GB0604109.9 2006-03-01
US77905806P 2006-03-27 2006-03-27
US60/779,058 2006-03-27
GB0611204.9 2006-06-07
GB0611204A GB2438895A (en) 2006-06-07 2006-06-07 Pyroelectric heat to electrical energy conversion
US81240506P 2006-06-12 2006-06-12
US60/812,405 2006-06-12

Publications (1)

Publication Number Publication Date
WO2007099279A1 true WO2007099279A1 (en) 2007-09-07

Family

ID=37946274

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2006/050400 WO2007099279A1 (en) 2006-03-01 2006-11-20 Thick and thin films for power generation and cooling

Country Status (1)

Country Link
WO (1) WO2007099279A1 (en)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8324783B1 (en) 2012-04-24 2012-12-04 UltraSolar Technology, Inc. Non-decaying electric power generation from pyroelectric materials
EP2622729A4 (en) * 2010-09-29 2015-09-30 Neothermal Energy Co Method and apparatus for generating electricity by thermally cycling an electrically polarizable material using heat from various sources and a vehicle comprising the apparatus
EP2622728A4 (en) * 2010-09-29 2015-09-30 Neothermal Energy Co Method and apparatus for conversion of heat to electrical energy using a new thermodynamic cycle
WO2018164068A1 (en) * 2017-03-06 2018-09-13 株式会社村田製作所 Composite oxide
US20180375008A1 (en) * 2015-12-21 2018-12-27 United Technologies Corporation Method of forming electrodes on electrocaloric film
CN110108770A (en) * 2019-05-10 2019-08-09 北京科技大学 High-flux electric card test system based on space thermal imaging
CN111525021A (en) * 2020-04-22 2020-08-11 济南大学 Sodium bismuth titanate-based film with positive and negative electrocaloric effects and preparation method thereof
CN111682799A (en) * 2019-06-03 2020-09-18 熵零技术逻辑工程院集团股份有限公司 Chemical engine
CN114665003A (en) * 2022-03-23 2022-06-24 湘潭大学 Flexible ferroelectric film containing defective dipole and manufacturing method thereof
US11566822B2 (en) 2017-06-16 2023-01-31 Carrier Corporation Ferroic response through application of conjugate field

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4425540A (en) * 1981-06-03 1984-01-10 Power Conversion Technology, Inc. Apparatus and method for pyroelectric power conversion
WO1992019564A1 (en) * 1991-05-01 1992-11-12 The Regents Of The University Of California Amorphous ferroelectric materials
WO1999009383A1 (en) * 1997-08-14 1999-02-25 Sandia Corporation Thermal infrared detector
EP1031545A2 (en) * 1999-02-22 2000-08-30 Infrared Integrated Systems Ltd. Ferroelectric ceramics
US20040013794A1 (en) * 2002-04-19 2004-01-22 Takashi Hashimoto Method for manufacturing piezoelectric element, piezoelectric element, and droplet-ejecting recording head
US20040207288A1 (en) * 2003-03-26 2004-10-21 Hiroshi Funakubo Method of producing lead zirconate titanate-based thin film, dielectric device and dielectric thin film

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4425540A (en) * 1981-06-03 1984-01-10 Power Conversion Technology, Inc. Apparatus and method for pyroelectric power conversion
WO1992019564A1 (en) * 1991-05-01 1992-11-12 The Regents Of The University Of California Amorphous ferroelectric materials
WO1999009383A1 (en) * 1997-08-14 1999-02-25 Sandia Corporation Thermal infrared detector
EP1031545A2 (en) * 1999-02-22 2000-08-30 Infrared Integrated Systems Ltd. Ferroelectric ceramics
US20040013794A1 (en) * 2002-04-19 2004-01-22 Takashi Hashimoto Method for manufacturing piezoelectric element, piezoelectric element, and droplet-ejecting recording head
US20040207288A1 (en) * 2003-03-26 2004-10-21 Hiroshi Funakubo Method of producing lead zirconate titanate-based thin film, dielectric device and dielectric thin film

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
SHEBANOVS L ET AL: "ELECTROCALORIC EFFECT IN SOME PEROVSKITE FERROELECTRIC CERAMICS AND MULTILAYER CAPACITORS", 2002, FERROELECTRICS, OVERSEAS PUBLISHERS ASSOCIATION, AMSTERDAM, NL, PAGE(S) 137-142, ISSN: 0015-0193, XP009082958 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2622729A4 (en) * 2010-09-29 2015-09-30 Neothermal Energy Co Method and apparatus for generating electricity by thermally cycling an electrically polarizable material using heat from various sources and a vehicle comprising the apparatus
EP2622728A4 (en) * 2010-09-29 2015-09-30 Neothermal Energy Co Method and apparatus for conversion of heat to electrical energy using a new thermodynamic cycle
US8324783B1 (en) 2012-04-24 2012-12-04 UltraSolar Technology, Inc. Non-decaying electric power generation from pyroelectric materials
US20180375008A1 (en) * 2015-12-21 2018-12-27 United Technologies Corporation Method of forming electrodes on electrocaloric film
US11448436B2 (en) * 2015-12-21 2022-09-20 United Technologies Corporation Method of forming electrodes on electrocaloric film
WO2018164068A1 (en) * 2017-03-06 2018-09-13 株式会社村田製作所 Composite oxide
US11566822B2 (en) 2017-06-16 2023-01-31 Carrier Corporation Ferroic response through application of conjugate field
CN110108770A (en) * 2019-05-10 2019-08-09 北京科技大学 High-flux electric card test system based on space thermal imaging
CN111682799A (en) * 2019-06-03 2020-09-18 熵零技术逻辑工程院集团股份有限公司 Chemical engine
CN111525021A (en) * 2020-04-22 2020-08-11 济南大学 Sodium bismuth titanate-based film with positive and negative electrocaloric effects and preparation method thereof
CN111525021B (en) * 2020-04-22 2023-08-22 济南大学 Bismuth sodium titanate-based film with positive and negative electric clamping effect and preparation method thereof
CN114665003A (en) * 2022-03-23 2022-06-24 湘潭大学 Flexible ferroelectric film containing defective dipole and manufacturing method thereof

Similar Documents

Publication Publication Date Title
WO2007099279A1 (en) Thick and thin films for power generation and cooling
Zhang et al. Lead-free ferroelectric materials: Prospective applications
Navid et al. Pyroelectric energy harvesting using Olsen cycles in purified and porous poly (vinylidene fluoride-trifluoroethylene)[P (VDF-TrFE)] thin films
Yang et al. Toward multifunctional electronics: flexible NBT-based film with a large electrocaloric effect and high energy storage property
Lu et al. Enhancement of the electrocaloric effect over a wide temperature range in PLZT ceramics by doping with Gd3+ and Sn4+ ions
Zhao et al. Orientation-dependent energy-storage performance and electrocaloric effect in PLZST antiferroelectric thick films
Seog et al. Recent progress in potassium sodium niobate lead-free thin films
Ji et al. Facile preparation and performance of novel high-TC xBi (Ni1/2Ti1/2) O3-(1-x) Pb (Zr1/2Ti1/2) O3 piezoceramics
Nguyen et al. Understanding the effects of electric-field-induced phase transition and polarization loop behavior on the energy storage performance of antiferroelectric PbZrO3 thin films
Suzuki et al. Orientation control and electrical properties of PZT/LNO capacitor through chemical solution deposition
Wang et al. Toward artificial intelligent self-cooling electronic skins: Large electrocaloric effect in all-inorganic flexible thin films at room temperature
Zhang et al. Enhanced piezoelectric performance of BiScO3-PbTiO3 ceramics modified by 0.03 Pb (Sb1/2Nb1/2) O3
Nguyen et al. High-performance energy storage and breakdown strength of low-temperature laser-deposited relaxor PLZT thin films on flexible Ti-foils
Dai et al. Field‐induced strains and polarization switching mechanisms in La‐modified lead zirconate titanate ceramics
Abe et al. RF-magnetron sputtering of piezoelectric lead-zirconate-titanate actuator films using composite targets
Zhu et al. Microstructures and dielectric properties of compositionally graded (Ba 1-x Sr x) TiO 3 thin films prepared by pulsed laser deposition
Tu et al. Flexible ferroelectric capacitors based on Bi3. 15Nd0. 85Ti3O12/muscovite structure
Yang et al. Piezoelectric and pyroelectric properties of Pb (Zr, Ti) O3 films for micro-sensors and actuators
Uhlmann et al. Ferroelectric films
Li et al. A new Pb (Lu1/2Nb1/2) O3–PbZrO3–PbTiO3 ternary solid solution with morphotropic region and high Curie temperature
Kaur et al. Agreement in experimental and theoretically obtained electrocaloric effect in optimized Bi 3+ doped PbZr 0. 5 2 Ti 0. 4 8 O3 material
Cheng et al. Lead zirconate titanate thin films prepared on metal substrates by the sol–gel methods
Yu et al. Defects engineered ferroelectricity and electrocaloric effect in Pb0. 7Ba0. 3ZrO3 ceramics
Xie et al. Phase transition, domain structure and electrical properties of Mn-doped 0.3 Pb (In1/2Nb1/2) O3-0.4 Pb (Mg1/3Nb2/3) O3-0.3 PbTiO3 crystals
Suzuki et al. Chemical solution deposition of conductive SrRuO3 thin film on Si substrate

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 06808764

Country of ref document: EP

Kind code of ref document: A1