GB2438895A

GB2438895A - Pyroelectric heat to electrical energy conversion

Info

Publication number: GB2438895A
Application number: GB0611204A
Authority: GB
Inventors: Alexandr Mishchenko
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-06-07
Filing date: 2006-06-07
Publication date: 2007-12-12
Also published as: GB0611204D0

Abstract

The devices incorporate pyroelectric thin or thick film dielectrics which exhibit the giant electrocalorific effect (eg Zr-rich PZT). The thin or thick films may be deposited using sol-gel, plasma-laser, magnetron sputtering or CVD methods. The device electrodes may comprise strontium-ruthenium oxide or iridium oxide.

Description

Thin and thick films for electrical power generation devices

Background Art

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 pyroelectiic effect can be described as an electrical current generated by a change of temperature of a pyroelectric material. The pyroelectiic effect is thermodynamically converse to the electrocaloric effect. Therefore materials with large electrocaloric effects are attractive for heat-to-electricity converters. This patent describes a potential that thin films have for heat-to-electricity conversion devices along with some particular material compositions especially interesting for heat-to-power converters.

Description of the invention

In a first aspect of the present invention, there is provided a working body of a device to convert heat into electrical power comprising at least one pyroelectiic thin or thick film element and a control input for controlling said pyroelectric thin film element.

A pyroelectric thin film element has a thickness of less than 1 m. 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 pm to 100 /.Lm, preferably from 1 to 10 jtm.

In one preferred embodiment of the invention, Zr-rich Pb(Zr,Tj)03 (PZT) pyroelectric films are used, e.g. Zr-rich films containing from 10-20 atomic % Zr, e.g. 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 % 0, e.g. a pyroelectric film comprising Pb(Zro.95Ti005)03 V:PJ'SA/AIe Mithchcnko/OBP29O724s G13P290724/G13 spcciflcatiot*fl/O7 06.06 In another embodiment of the present invention, Pb(Mg,Nb)03 -PbTiO3 (PMN-PT) pyroelectric films are used. One preferred embodiment of such a pyroelectric thin film comprises up to 25 atomic % Pb, up to 10 atomic % Mg, up to atomic % Nb, up to 5 atomic % Ti and up to 80 atomic % 0, e.g. a pyroelectric film comprising 0.9 Pb(Mg1i3Nb2i3)03 -0.1 PbTiO3 In another embodiment of the invention, PbSc05Ta05O3 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 % 0, In another preferred embodiment of the invention, (1-x) PbSc0.5Ta05O3 -x PbSc0.5Nb0,503 pyroelectric films are used, where x represents respective atomic percentages of respective portions of the material, and 0 x S 0.5.

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, up to 15 atomic % Nb, and up to 70 atomic % 0, In another preferred embodiment of the invention, pyroelectric films of PbSco.5Tao,503 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 % 0. Other preferred embodiments of such a pyroelectric thin film comprise up to 30 atomic % Pb, up to 15 atomic % Sc, up to 15 atomic % Ta, up to 70 atomic % 0; 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)O3 pyroelecti-ic thin and thick film materials, e.g. Pb0995Nb001 (Zro65Tio35)o.99O3, V:/TSA/AJcx MishchcnkofGflP29O724 013P290724/G13 specifica(ianflsaJO7,06.06 Pb0 99Nb0.02(Zro,43Sn0,43Ti0,1 4)0.0803, Pbo,99Nbo02(Zro455Sno455Ti0.09)0.9803, or Pbo 99Nb0 02(Zro 75Sn0 2Tio,05)o.9803, 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 % 0.

In another preferred embodiment of the invention, pyroelectric films of a(PbMgo.33Nbo.(,703) -b(PbTiO3) -c(SrTiO3), where a, b and c represent respective atomic percentages of respective portions of the material and 0.3 <a S 0.9, 0.05 b 0.6, 0 cS 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 atomic % Nb, up to 20 atomic % Ti, up to 10 atomic % Sr and up to atomic % 0.

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 1r02. One preferred example of an SrRuO3 thin film comprises up to 25 atomic % Sr, up to 25 atomic % Ru, and up to 70 atomic % 0, while one preferred example of an 1r02 thin film comprises up to 35 atomic % Ir and up to 75 atomic % 0.

Description of Figures

Fig. 1. An example diagram for an elementary heat-to-electricity cycle based on the data for PbZr0 95Ti005O3 from [1].

Fig. 2. Energy gained per one elementary cycle in Fig, I exceeds the best result so far [2] by a factor of 10. Hysteresis loss is around 20% as estimated form the area of the hysteresis loop at 220 C [1].

Fig. 3. Energy gained per one elementary cycle for three values AT.

V:/TSAIAIex MishchenkoIGBP29O724s GBP290724/013 speci1icuioaflsa/07.06.06 Fig. 4. Entropy -temperature (S -7') diagram for different values of an applied electric field for PbZr0,95Ti00503. The total entropy is estimated (e.g. as described in [5]) using the data disclosed in [1]. The cycle A-B-C-D is an ideal Camot cycle.

Detailed Description

The electrocaloric 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 thermodynamically converse. Assuming reversible thermodynamics, the electrocaloric temperature change ET caused by a change of an applied electric field from E1 to E2 at a temperature T in a material with heat capacity C and density p can be estimated by AT=__LJTPdE, (I) where p = (aT)E is the pyroelecific 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 [2-4]. The inherent efficiency of the heat-to-electricity conversion by means of the pyroelectric effect in bulk materials is up to 90% [2] 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. V;/TSA/Mcx MishchcnkoIGBPZ9Ol24s 0BP290724/G13 speciflcuion/tsa/O7 06.06 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. 50-100 C around the peak temperature for PZT [1]). It makes thin films especially attractive for use in devices for the generation of electrical power from waste heat.

* Large electrocaloric 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 -50 C to 300 C.

* Large cooling power and energy output per one working element can be achieved by producing thicker films and/or multilayered structures.

In some embodiments of the present invention, thin or thick pyroelectric films are deposited on oxide electrodes, e.g. on SrRuO3 [5, 6] or 1r02 [6] 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 [7-14]. As shown in [1J, 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 the present invention.

V:fTSAJAJcx MhchkofGI3P29O724s GBP290724/GB spccificalion/tsa/07.O(j,06

Description of an example experiment

A giant electrocaloric effect in thin film Zr-rich Pb(Zr,Ti)03 (PZT) was reported in [1}. The effect is associated with the paraelectric-to-ferroelectric phase transition in PZT. The experimental data used for [1] 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 Tc0Id = 190 C and TH0t = 240 C are shown in Fig. 1. In one embodiment of the present invention, an elementary cycle for heat-to-electricity converter comprises (see Fig. 1): * an increase of an applied electric field across the thin film from E1 to E2 at the temperature (path A-B in Fig. 1) * heating the thin film to the temperature THigh with the field E2 still applied (path B-C in Fig. 1) and collecting the electrical current due to the pyroelectric effect associated with heating, * a decrease of an applied electric field from E2 to E1 at the temperature THigh (path C-D in Fig. 1), and * cooling the film to the temperature with the electric field E, still applied (path D-A in Fig. 1).

The electrical energy (per 1 cm3) w gained in one elementary cycle described above can be estimated as w= cJPdE, (2) t-fl-C-D 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. 1. Among other parameters, the energy v gained per one cycle depends on the temperature difference tT = THL5h - and on the average temperature TAvg = O.5(THjg)-T%y), as shown in Figs. 2 and 3. The energy output of Zr-rich PZT films shown in the figures exceeds the results reported in literature [2-4] 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 [2], and Zr-rich PZT films have much higher polarisation values than the polymers used in prior art documents such as [4].

VI1'SA/Aex MishchenkoIGBP29O724s GBP29O724IGf3 spccification/tsi1O7 06.06 Crystalline entropy SCFSI of a material at a temperature T can be estimated as = J-.dT, (3) where C is the heat capacity of the material. A change of an applied electric field from E1 to E2 induces a change ISDip of the entropy of the system of electrical dipoles of the material according to _jdE (4) where P is polarisation and E1 and E2 were explained above. The total entropy of a material is therefore S = Scrysi + MDp (5) An ideal (Carnot) thermodynamic cycle for a heat-to-electricity converter of the present example experiment is shown in Fig. 4 in S-T variables, where S is the total entropy, and T is the temperature of Zr-rich PZT thin films from [1]. This cycle is well known for people acquainted with the field. The Carnot cycle is different from that discussed above and illustrated in Fig. 1. Indeed, the Carnot cycle requires increase of the temperature of a material from T1 to THj5I (path B-C in Fig. 4) 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. 4). 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.

ViTS&AIc Mi5hchcnk&QBP29O724 GBP290724/G13 spcciflcaiion/tsa/07.06o6 References 1. A.S. Mischenko Q. Zhang, J.F. Scott, R.W. Whatmore, and N.D. Mathur. Science 311, 1270 (2006).

2. R.B. Olsen and D. Evans. J. App!. Plzys. 54, 5941 (1983) 3, R.B. Olsen. US Patent No 4647836 (1987) 4. R.B. Olsen, D.A. Bruno, J.M. Briscoe and E.W. Jacobs. J. App!. Phys. 57, 5036 (1985) 5. U. Ellerkmann et a!., integrated Ferroelectrjcs. 52, 63 (2003).

6. K. Maid et a!., integrated Ferroelectrics. 52, 19 (2003).

7. P.D. Thacher, J. Appi. Phys. 39, 1996 (1968).

8. B.A. Tuttle, PhD Thesis, University of Illinois at Urbana -Champaign (1981).

9. B.A. Tuttle and D.A. Payne, Ferroelectrjcs 37, 603 (1981).

10. E.H. Birks, L.A. Shebanov, K.Ya. Bormanis, M.Ya. Dambekalne. SU Patent No SU1479440 (1986).

11. L.A. Shebanov, E.H. Birks and K,J. Borman, Ferroelectrjcs 90, 165 (1989).

12. L. Shebanov and K, Borman, Ferroelectrjcs, 127, 143 (1992).

13. W.N. Lawless, US Patent US6877325 (2005).

14. L. Shaobo and L. Yanqiu, Mat. Sci. and Eng. 113, 46 (2004).

V:/TSA/AIex Mishchcnko/GflP29O724 GBP290724/Ofl spcciuicnionJ1o7.otjo,j

Claims

CLAIMS

1, Working body of a device for converting of heat to electrical energy comprising at least one pyroelectric thin or thick film element and a control input for controlling said pyroelectric thin film element.

2. Working body as claimed in claim I, wherein said thin or thick film is deposited by sol-gel deposition.

3. Working body as claimed in claim 2, wherein said thin or thick film is deposited by dip coating.

4. Working body as claimed in claim 2, wherein said thin or thick film is deposited by spin coating.

5. Working body as claimed in claim 1, wherein said thin or thick film is deposited by a plasma laser deposition system.

6. Working body as claimed in claim 1, wherein said thin or thick film is deposited by a magnetron sputtering system.

7. Working body as claimed in claim 1, wherein said thin or thick film is deposited by a chemical vapour deposition system.

8. Working body as claimed in any one of claims Ito 7, wherein said 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 % 0.

9. Working body as claimed in any one of claims ito 7, wherein said pyroelectric thin or thick film element is deposited on hO2 thin film that consists of essentially up to 35 atomic % Ir and up to 75 atomic % 0.

10. Working body as claimed in any one of claims ito 9, comprising at least one pyroelectric thin film element.

V1TSA/Alx MjsIicIinkcj/GUP29O'724 0BP290724/GB spccifIca(ion/tsa/07.06,06 11. Working body as claimed in claim 10, wherein said pyroelectric thin film element has a thickness of less than 1 jim.

12. Working body as claimed in claim 10, wherein said pyroelectric thin film element has a thickness of from 10 to 900 nm.

13. Working body as claimed in claim 10, wherein said pyroelectiic thin film element has a thickness of from 50 to 500 nm.

14. Working body as claimed in any one of claims ito 9, comprising at least one pyroelectric thick film element.

15, Working body as claimed in claim 14, wherein said pyroelectric thick film element has a thickness of from 1 jm to 100 jim.

16. Working body as claimed in claim 14, wherein said pyroelectric thick film element has a thickness of from 1 to 10 j.m.

17. Working body as claimed in any one of claims ito 16, wherein said at least one pyroelectric thin or thick film element comprises a PbSco5Ta0503 pyroelectric film.

18. Working body as claimed in claim 17, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to 15 atomic % Sc, up to iS atomic % Ta and up to 70 atomic % 0.

19. Working body as claimed in any one of claims 1 to 16, wherein said at least one pyroelectric thin or thick film element comprises a (1-x) PbSco,5Ta05O3 -x PbSc0,5Nb0503 pyroelectric film, wherein x represents the atomic proportions of the respective proportions of the material and 0 =x =0.5.

20, Working body as claimed in claim 19, 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 % 0 V:!TSAJAIcx Mishchcnk&013p291J724s G13P29072411JB spcciflcatjonJst/O7O5 ii 21. Working body as claimed in any one of claims ito 16, wherein said at least one pyroelectric thin or thick film element comprises up to 30 atomic % Pb, up to atomic % Sc, up to 15 atomic % Ta, up to 15 atomic % Nb, and up to atomic % 0.

22. Working body as claimed in any one of claims ito 16, wherein said at least one pyroelectric thin or thick film element comprises a pyroelectric film of PbSc05Ta05O3 with up to 20 atomic % substitution of Sc ions by Co, Fe, Ni, or Mn.

23. Working body as claimed in claim 22, 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 % 0.

24. Working body as claimed in claim 22, 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 % Ni, and up to 70 atomic % 0.

25. Working body as claimed in claim 22, 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 % 0.

26. Working body as claimed in any one of claims ito 16, wherein said at least one pyroelectric thin or thick film element comprises a pyroelectric film of PbSc0.5Ta0503 with up to about 20 atomic % substitution of Sc and Ta ions by Co, Sb, Nb, Ti, In, Ga, Zn, Y, V, Zr, Hf, orSn.

27. Working body as claimed in claim 26, 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 % 0.

28. Working body as claimed in claim 26, 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 % 0.

V:fFSA/AIx MisIicIicnkoIGBP29Q724 GBP290724/013 spcicaton/isa/O7.O6.Oj 29. Working body as claimed in claim 26, 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 % 0.

30. Working body as claimed in claim 26, 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 % 0.

31. Working body as claimed in claim 26, 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 % 0.

32. Working body as claimed in claim 26, wherein said at least one pyroelectiic 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 % 0.

33, Working body as claimed in claim 26, 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 % 0.

34. Working body as claimed in claim 26, 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 % 0.

35. Working body as claimed in claim 26, 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 % 0.

36. Working body as claimed in claim 26, 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 % 0.

V:ITSA/AIcx Mishchcriko/GI3P29Q724s GBP2907241GB spcci1uCation/taJO7,O6.

37. Working body as claimed in claim 26, 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 % 0.

38. Working body as claimed in claim 26, 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 % 0.

39. Working body as claimed in any one of claims I to 16, wherein said at least one pyroelectric thin or thick film element comprises a Nb-doped Pb(Zr,Sn,Ti)03 pyroelectric film.

40. Working body as claimed in claim 39, 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 % 0.

41. Working body as claimed in claim 40, wherein said at least one pyroelectric thin or thick film element comprises Pbo995Nbo.oi(Zro.osTio35)09903.

42. Working body as claimed in claim 40, wherein said at least one pyroelectric thin or thick film element comprises Pbo.99Nbo02(Zro43Sn043Ti01 4)0.9803.

43. Working body as claimed in claim 40, wherein said at least one pyroelectric thin or thick film element comprises Pbo99Nbo.o2(Zro45sSno455Tj0)098O3.

44. Working body as claimed in claim 40, wherein said at least one pyroelectric thin or thick film element comprises Pbo99Nboo2(ZroisSno2Tjoo5)09803.

45. Working body as claimed in any one of claims ito 16, wherein said at least one pyroelectric thin or thick film element comprises a a(PbMgo.33Nb0.5703) -b(P5TiO3) -c(SrTiO3) electrocaloric film, where a, b and c represent respective atomic percentages of respective portions of said pyroelectric thin or thick film material.

V:ITSAJAIex Mishchcnko/013p290724s OBI'290724/cj13 spccificaon/tj/o7o6yj 46. Working body as claimed in claim 45, 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.

47. Working body as claimed in claim 45, wherein 0.3 a 0.9, 0.05 b 0.6 and 0c =O.15.

48. Working body as claimed in claim 45, wherein said pyroelectric thin film comprises up to 30 atomic % Pb, up to 10 atomic % Mg, up to 15 atomic % Nb, up to atomic % Ti, up to 10 atomic % Sr and up to 70 atomic % 0.

49. Working body as claimed in any one of claims Ito 16, wherein said at least one pyroelectric thin or thick film element comprises a Zr-rich Pb(Zr,Ti)03 (PZT) pyroelectric film.

50. Working body as claimed in claim 49, wherein said Zr-rich Pb(Zr,Ti)03 (PZT) pyroelectric film Contains from 15-25 atomic % Zr.

51. Working body as claimed in claim 49, wherein said at least one pyroelectric thin or thick film element compi-ises up to 15 atomic % Pb, up to 12 atomic % Zr, up to 5 atomic % Ti and up to 75 atomic % 0.

52. Working body as claimed in claim 49, wherein said at least one pyroelectric thin or thick film element comprises up to 25 atomic % Pb, up to 25 atomic % Zr, up to 2 atomic % Ti and up to 65 atomic % 0.

53. Working body as claimed in claim 49, wherein said at least one pyroelectric thin or thick film element comprises Pb(Zro,95Tioo5)03 54. Working body as claimed in any one of claims Ito 16, wherein said at least one pyroelectric thin or thick film element comprises a Pb(Mg,Nb)03-PbTiO3 pyroelectric film.

V:/TSA/AI M ishchcnko/Q13P2907245 0BP29072410fl speciflcation/O7.

55. Working body as claimed in claim 54, wherein said at least one pyroelectric thin or thick film element comprises up to 25 atomic % Pb, up to 10 atomic % Mg, up to atomic % Nb, up to 5 atomic % Ti and up to 80 atomic % 0.

56. Working body as claimed in claim 54, wherein said at least one pyroelectric thin or thick film element comprises 0.9 Pb(Mg1j3Nb3)03 -0.1 PbTiO3 V:ITSA/AIcx Mishchcnko/GBP2907245 G13P290724/OB spcci(citonhtstiO7 06.06