阅读说明：本技术 基于氧化钨的材料 (Tungsten oxide based materials ) 是由 马克·卡特 杰克·卡罗 大卫·克罗斯利 于 2018-02-02 设计创作，主要内容包括：本发明提供一种式(I)(M<Sub>y</Sub>A<Sub>x</Sub>WO<Sub>z</Sub>(I))的材料,其中M表示一种或多种单原子物质,A表示一种或多种多原子阳离子物质,每种该多原子阳离子物质的离子半径不大于<Image he="64" wi="95" file="DDA0002259181170000011.GIF" imgContent="drawing" imgFormat="GIF" orientation="portrait" inline="no"></Image>W为钨,O为氧,y为非零并且至多且包括0.32,x为非零并且至多且包括0.32,并且z为2.5至4.0,条件是x+y≤0.33。(The present invention provides a compound of formula (I) (M) y A x WO z (I) In which M represents one or more monoatomic species and A represents one or more polyatomic cationic species, each of which has an ionic radius of not more than W is tungsten, O is oxygen, y is non-zero and up to and including 0.32, x is non-zero and up to and including 0.32, and z is from 2.5 to 4.0, with the proviso that x + y ≦ 0.33.)

1. A material of formula (I)

M_yA_xWO_z (I)

Wherein M represents one or more monoatomic species,

a represents one or more polyatomic ionic species, each of which has an ionic radius of not more than

W is tungsten, O is oxygen, y is non-zero and up to and including 0.32, x is non-zero and up to and including 0.32, and z is from 2.5 to 4.0, with the proviso that x + y ≦ 0.33.

2. The material of claim 1, wherein x + y ≧ 0.30.

3. The material of claim 2, wherein x + y is 0.33.

4. A material according to any preceding claim, wherein a represents one or more polyatomic cationic species.

5. A material according to claim 4, wherein A represents NH₄ ⁺、H₃O⁺、VO²⁺、H₂F⁺And H₃S⁺One or more of (a).

6. A material according to claim 5, wherein A represents NH₄ ⁺。

7. A material according to any preceding claim, wherein M represents one or more metals.

8. A material according to any preceding claim, wherein M represents one or more of: alkali metals, alkaline earth metals, rare earth elements, Zr, Cu, Ag, Zn, Al, Ga, In, Tl, Ge, Sn, Pb, Sb, Ti, Nb, V, Mo, Ta, Re, Be, Hf and Bi.

9. The material of claim 8, wherein M represents one or more of: alkali metals, alkaline earth metals, Ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo and Ta.

10. The material of claim 9, wherein M represents one or more of: alkali metals, Sn and Pb.

11. The material of claim 10, wherein M represents one or more of: alkali metal, and Sn or Pb.

12. A material according to claim 11, wherein M represents an alkali metal and Sn or Pb.

13. A material according to any one of claims 1 to 5 and 7 to 12, wherein a represents n polyatomic species a1, a2,.. An, wherein n is 2 or greater, and a represents a1_x1、A2_x2、….An_xnWhere x ═ Σ (x1, x2, …. xn).

14. Material according to any one of the preceding claims, wherein M represents n monoatomic species M1, M2, …. Mn, wherein n is 2 or more and M represents M1_y1、M2_y2、….Mn_ynWhere x ═ Σ (y1, y2, …. yn).

15. A material according to any preceding claim, wherein M represents one or more monoatomic species, each species M having an ionic or atomic radius no greater than

16. A material according to any preceding claim, wherein M comprises one or more group I elements.

17. A material according to any preceding claim, wherein M comprises Sn or Pb.

18. The material of claim 17, wherein M comprises one or more group I elements and Sn.

19. A material according to any preceding claim, wherein x is at least 0.02.

20. A material according to any preceding claim, wherein x is not greater than 0.25.

21. A material according to any preceding claim, wherein x is from 0.02 to 0.18.

22. A material according to any preceding claim, wherein y is at least 0.05.

23. A material according to any preceding claim, wherein y is not greater than 0.30.

24. A material according to any preceding claim, wherein y is from 0.10 to 0.30.

25. A material according to any preceding claim, wherein z is from 2.5 to 3.5.

26. The material of any preceding claim, wherein z is at least 2.8.

27. The material of any preceding claim, wherein z is at least 3.0.

28. The material of claim 26 or claim 27, wherein z is at most 3.3 and includes 3.3.

29. The material of claim 1, wherein x is from 0.10 to 0.20, y is from 0.10 to 0.20, wherein a represents ammonium, and M represents one or more of the following (optionally one of the following): alkali metals, Ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo and Ta.

30. The material of claim 1, wherein x is 0.02 to 0.10, y is 0.20 to 0.31, x + y ≧ 0.30, A represents ammonium, and M represents one or more of Na, K, and Cs, and one or more of Sn, Pb, Nb, Mo, and Ta.

31. A composition comprising the material of any preceding claim dispersed in a carrier.

32. The composition of claim 31, wherein the carrier comprises a vaporizable liquid.

33. A method of making a material according to any one of claims 1 to 23, the method comprising providing the monoatomic species M (or a source thereof), the polyatomic species a (or a source thereof), and WO in admixture_zThe source of (a).

34. The method of claim 33, wherein WO_zThe source of (a) includes a tungsten (VI) species and a reducing agent.

35. The method of claim 33 or claim 34, wherein WO_zThe source of (A) comprises tungstic acid or a tungstate (WO)₄ ^2-)。

36. The method of any one of claims 33 to 35, wherein the monatomic substance M (or source thereof), polyatomic substance a (or source thereof), and WO are provided as an admixture under acidic conditions_zThe source of (a).

37. The method of any one of claims 33 to 36, comprising heating the blend to form a product.

38. The method of claim 37, wherein the product so formed is filtered, dried and heated in an inert atmosphere.

39. A method of providing an object with infrared absorption capability, the method comprising providing the object with a material according to any one of claims 1 to 30.

40. A method according to claim 39, comprising providing the object with a composition according to claim 31 or 32.

Technical Field

The present disclosure relates to tungsten oxide.

The present invention relates to tungsten oxide. More particularly, but not exclusively, the invention further relates to compositions comprising tungsten oxide and methods of making tungsten oxide.

Background

Tungsten oxide incorporating polyatomic cations such as ammonium or metals such as potassium is known. Some such tungsten oxides absorb Infrared (IR) radiation and, therefore, are used to provide infrared absorbing properties despite the fact that the infrared absorbing properties of such tungsten oxides are not sufficiently high. Some tungsten oxides absorb light in the visible portion of the spectrum, which may be undesirable in certain circumstances, for example where it is desired that tungsten oxide not have a significant adverse effect on the visible color of the matrix in which it is dispersed.

The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide improved tungsten oxide.

Disclosure of Invention

According to a first aspect of the present invention there is provided a material of formula (I)

M_yA_xWO_z (I)

Wherein M represents one or more monoatomic species,

a represents one or more polyatomic ionic species, each having an ionic radius of not more thanW is tungsten, O is oxygen, y is non-zero and up to and including 0.32, x is non-zero and up to and including 0.32, and z is from 2.5 to 4, with the proviso that x + y ≦ 0.33.

It has been found that the material of the first aspect of the invention can provide infrared absorbing properties.

W represents tungsten, optionally in ionic form. Tungsten may be present in more than one oxidation state.

Species a and M are typically located in interstitial voids or spaces in the crystal lattice.

The material of formula (I) may comprise a tungsten oxide lattice of tungsten and oxygen, optionally with species a and M in the interstitial voids or spaces of the lattice.

The material of formula (I) may comprise a crystal lattice that is substantially free of anything other than oxygen and tungsten.

A optionally represents one or more polyatomic cationic species.

x is optionally at least 0.02, optionally at least 0.03, optionally at least 0.04, optionally at least 0.05, optionally at least 0.08, optionally at least 0.10, optionally at least 0.15, optionally at least 0.18, optionally at least 0.20, and optionally at least 0.25. x is optionally no greater than 0.30, optionally no greater than 0.28, optionally no greater than 0.25, optionally no greater than 0.20, optionally no greater than 0.18, and optionally no greater than 0.15. x can optionally be 0.02 to 0.20, optionally 0.02 to 0.18, and optionally 0.02 to 0.17. For example, x can optionally be 0.11, 0.18, 0.22, or 0.25. In the case where x is 0.11, the ratio of a to W is 1 to 9. In the case where x is 0.22, the ratio of a to W is 2 to 9.

In certain instances, x is optionally 0.02 to 0.10, optionally 0.02 to 0.08, optionally 0.02 to 0.06, and optionally 0.02 to 0.05. In these cases, y is optionally 0.20 to 0.30. It has been found that certain materials containing relatively small amounts of polyatomic species, particularly ammonium, in combination with other species, can provide materials with infrared absorbing properties.

In certain instances, x is from 0.10 to 0.30, and optionally from 0.10 to 0.20. It has been found that a material comprising about the same amounts (on a molar basis) of polyatomic species a (particularly ammonium) and species M can provide a material having infrared absorbing properties.

x refers to the total content of A. For the avoidance of doubt, a may represent more than one polyatomic species. For example, if a represents n polyatomic substances a1, a2,. An, where n is 2 or greater, then a represents a1_x1、A2_x2、….An_xnWhere x ═ Σ (x1, x2, …)Xn). For example, if A represents two polyatomic substances A1 and A2, then A represents A1_x1A2_x2And x is x1+ x 2.

y is optionally at least 0.05, optionally at least 0.08, optionally at least 0.12, and optionally at least 0.15, optionally at least 0.20, and optionally at least 0.25. y is optionally no greater than 0.31, optionally no greater than 0.30, optionally no greater than 0.28, optionally no greater than 0.25, optionally no greater than 0.22, optionally no greater than 0.20, optionally no greater than 0.18, optionally no greater than 0.15, and optionally no greater than 0.10. For example, y is optionally 0.08, 0.11, 0.15, or 0.22. The ratio of M to W is optionally from 1 to 9 where y is 0.11, and from 2 to 9 where y is 0.22.

In certain instances, y is optionally 0.02 to 0.31, optionally 0.05 to 0.30, optionally 0.10 to 0.30, and optionally 0.10 to 0.20. It has been found that a material comprising about the same amounts (on a molar basis) of polyatomic species a (particularly ammonium) and species M can provide a material having infrared absorbing properties.

In certain instances, y is optionally 0.20 to 0.30, optionally 0.22 to 0.30, optionally 0.24 to 0.30, and optionally 0.24 to 0.30. In those cases, x can optionally be 0.02 to 0.10, optionally 0.02 to 0.05. It has been found that certain materials containing relatively small amounts of polyatomic species, particularly ammonium, in combination with other species, can provide materials with infrared absorbing properties.

y refers to the total content of M. For the avoidance of doubt, M may represent more than one monoatomic species. For example, if M represents n monoatomic species M1, M2,. Mn, where n is 2 or greater, then M represents M1_y1、M2_y2、….Mn_ynWhere x ═ Σ (y1, y2, …. yn). For example, if M represents two monoatomic species, M1 and M2, then M represents M1_x1M2_x2And y1+ y 2.

Optionally x + y ≧ 0.15, x + y ≧ 0.18, x + y ≧ 0.20, x + y ≧ 0.23, x + y ≧ 0.25, optionally x + y ≧ 0.28, optionally x + y ≧ 0.30, optionally x + y ≧ 0.31, optionally x + y ≧ 0.32, and optionally x + y ≧ 0.33.

M optionally represents one or more monoatomic species. M is optionally one or more monoatomic ions. The ionic or atomic radius of each species M is optionally not greater thanM optionally represents a plurality of monoatomic species, optionally two monoatomic ions. One or more of the species M may be a metallic species. M may represent one or more monoatomic metal species, optionally a plurality of monoatomic metal species, optionally two monoatomic metal species. M may comprise (or optionally represent) one or more of: H. he, alkali metal (group I), alkaline earth metal (group II), rare earth element, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, Cl, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi and I.

M may comprise (or optionally represent) one or more of: alkali metals, alkaline earth metals, rare earth elements, Zr, Cu, Ag, Zn, Al, Ga, In, Tl, Ge, Sn, Pb, Sb, Ti, Nb, V, Mo, Ta, Re, Be, Hf and Bi. M may comprise (or optionally represent) one or more of: alkali metals, alkaline earth metals, rare earth elements, Zr, In, Tl, Ge, Sn, Pb, Sb, Ti, Nb, V, Mo and Ta. M may comprise (or optionally represent) one or more of: alkali metals, alkaline earth metals, Ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo, Ta. M may comprise (or optionally represent) one or more of: alkali metals, alkaline earth metals, Sn and Pb. M optionally comprises (or optionally represents) one or more of: alkali metals (particularly one or more of sodium, potassium and cesium), Sn and Pb; optionally comprising one or more of the following: alkali metal and one of Sn or Pb. It has been found that Sn and an alkali metal (group I), either alone or in combination, can effectively provide a material with good infrared absorption properties when used in combination with polyatomic species a, particularly ammonium.

If M represents a plurality of monoatomic species, preferably, each of the monoatomic species can Be selected from H, He, alkali metals, alkaline earth metals, rare earth elements, Mg, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ir, Ni, Pd, Pt, Cu, Ag, Au, Zn, Cd, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Sb, B, F, Cl, P, S, Se, Br, Te, Ti, Nb, V, Mo, Ta, Re, Be, Hf, Os, Bi, and I. If M represents a plurality of monoatomic species, each of the monoatomic species can optionally Be selected from the group consisting of alkali metals, alkaline earth metals, rare earth elements, Zr, Cu, Ag, Zn, Al, Ga, In, Tl, Ge, Sn, Pb, Sb, Ti, Nb, V, Mo, Ta, Re, Be, Hf, and Bi. If M represents a plurality of monoatomic species, each of the monoatomic species can be optionally selected from the group consisting of alkali metals, alkaline earth metals, rare earth elements, Zr, In, Tl, Ge, Sn, Pb, Sb, Ti, Nb, V, Mo, and Ta. If M represents a plurality of monoatomic species, optionally, each of the monoatomic species can be selected from the group consisting of alkali metals, alkaline earth metals, Ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo, Ta. If M represents a plurality of monoatomic species, each of the monoatomic species can be optionally selected from the group consisting of alkali metals, alkaline earth metals, Sn, and Pb. M optionally represents one or more alkali metals (optionally one alkali metal, optionally two alkali metals) and Sn or Pb.

M may comprise one or more group I elements, optionally in ionic form, and/or one or more group II elements, optionally in ionic form, optionally in combination with additional monatomic species (such as a monatomic metal species), optionally selected from the group consisting of: ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo and Ta, optionally selected from the group consisting of: pb and Sn, optionally an ion. M may comprise one or more of Na, K, Cs, Mg, Ca, Sr or Ba (optionally one or more of Na, K and Cs), optionally in ionic form, optionally in combination with additional monatomic species (such as a monatomic metal species), optionally selected from the group consisting of: ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo and Ta, optionally selected from the group consisting of Pb and Sn, optionally in ionic form, such as Sn ions. M may comprise one or both of Na and Cs, optionally in ionic form, optionally in combination with additional monatomic species (such as a monatomic metal species, such as Sn ions).

M may comprise one or more of Ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo and Ta (optionally one or both of Pb and Sn), optionally in ionic form, optionally in combination with one or more additional monatomic species, such as one or more group I elements, optionally in ionic form, and/or one or more group II elements, optionally in ionic form. M may comprise one or more of Ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo and Ta (optionally one or both of Pb and Sn) in combination with: ions of one or more of Na, K and Cs, optionally one or more ions of one or both of Na and Cs, optionally one or more ions of Na and optionally one or more ions of Cs. M may comprise Sn (optionally in ionic form), optionally in combination with: (i) na (Na)⁺And Cs⁺，(ii)Na⁺And K⁺，(iii)K⁺And Cs⁺Or (iv) Na⁺、K⁺And Cs⁺。

The material of formula (I) may have formula (II) wherein x is from 0.10 to 0.20 (optionally from 0.15 to 0.20), y is from 0.10 to 0.20 (optionally from 0.15 to 0.20), wherein A represents ammonium, x + y ≧ 0.30, and M represents one or more of an alkali metal, Ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo, and Ta, optionally one or more of Li, Na, K, Cs, Rb, Pb, and Sn, and optionally one or more of Na, K, Cs, Pb, and Sn, optionally one of Na, K, Cs, Pb, and Sn. It has been found that such materials can effectively provide infrared absorption properties.

The material of formula (I) may have formula (III) wherein x is from 0.02 to 0.10 (optionally from 0.02 to 0.08, optionally from 0.03 to 0.06), y is from 0.20 to 0.31, x + y ≧ 0.30, A represents a single polyatomic species such as ammonium, and M represents one or more of Na, K, Cs, Mg, Ca, Ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo, and Ta. Optionally, M represents one or more of Na, K, Cs, Ti, Zr, Hf, Ge, Sn, Pb, Nb, Mo and Ta. Optionally, M represents one or more of Na, K, Cs, Sn, Pb, Nb, Mo and Ta. Optionally, M represents one or more of Na, K and Cs, and one or more of Sn, Pb, Nb, Mo and Ta. Optionally, M represents one or more of Na, K and Cs, and one or both of Sn and Pb; in this case, y for Na, K and Cs is optionally 0.10 to 0.28 (optionally 0.15 to 0.25), and y for Sn and Pb is 0.02 to 0.15 (optionally 0.05 to 0.15).

A optionally represents one or more polyatomic species, such as one or more polyatomic cations, such as ammonium.

A optionally represents one (and only one) polyatomic species, such as a polyatomic ion, such as a polyatomic cation, such as ammonium. It has been found that combining ammonium with other dopants can in some cases improve the infrared absorption properties.

A optionally represents a plurality of polyatomic species, such as polyatomic cations.

A may comprise NH₄ ⁺、H₃O⁺、VO²⁺、H₂F⁺And H₃S⁺One or more of (A), e.g. NH₄ ⁺And H₃O⁺、VO²⁺、H₂F⁺And H₃S⁺One or more combinations thereof. A may comprise NH₄ ⁺And H₃O⁺Or NH₄ ⁺And VO²⁺Or NH₄ ⁺And H₂F⁺Or NH₄ ⁺And H₃S⁺。

A may comprise a metal (typically in combination with other elements). A may not contain metal.

Optionally, A represents NH₄ ⁺. Optionally, M represents Sn (optionally in combination with a group I element or a group II element), and y is optionally at least 0.02, optionally 0.08 or 0.15.

z can be 2.5 to 3.5, optionally 2.5 to 3.2, and optionally 2.7 to 3.1, and optionally 2.9 to 3.1. z can be at least 2.7, optionally at least 2.8, optionally at least 3.0, and optionally at least 3.2. z may optionally be no greater than 3.5, and mayOptionally up to 3.3 (and including 3.3). z may be 3 (the material optionally comprises WO)₃)。

The tungsten oxide of formula (I) of the first aspect of the invention is a single phase material, not a mixture or blend of a plurality of different materials, or a monoatomic or polyatomic species merely blended with a tungsten oxide support. This can be demonstrated using X-ray diffraction. A single phase material will typically produce the diffraction pattern characteristics of such a material. Mixtures or blends of different materials will produce an X-ray diffraction pattern for each different material. Similarly, if a single atom material is blended into a material such as WO₃In the support of (3), it is expected that an X-ray diffraction pattern from the support is observed, and it is possible that an X-ray diffraction pattern from a monoatomic material is observed.

According to a second aspect of the present invention there is provided a composition comprising a material of formula (I) dispersed in a carrier.

The carrier may, for example, comprise a vaporizable liquid, such as those used in coatings. The vaporizable liquid can be aqueous or non-aqueous. The word "vaporizable" indicates that the liquid (or a sufficient portion thereof) is vaporized under the conditions in which the composition is used, to generally provide a coating. For example, "vaporizable" may indicate that, in use, the liquid is vaporized at a temperature of 20 ℃ for a period of time not exceeding 12 hours to optionally provide a coating.

The carrier may optionally be a liquid or solid. The carrier may be a liquid that can be treated (e.g., after evaporation of the liquid or a substantial portion of the liquid) to form a solid. After the treatment for forming a solid is carried out, the solid subsequently formed comprises the material of formula (I) dispersed in said solid.

The amount of material of formula (I) dispersed in the carrier will depend on the intended use of the composition. Optionally, sufficient material of formula (I) is present to provide effective Infrared (IR) absorption/shielding properties. Such absorption/shielding properties may optionally be measured at a nominal wavelength of 1039 nm.

According to a third aspect of the present invention there is provided a method of preparing a material of formula (I), the method comprising providing a monoatomic species M (or a source thereof), a polyatomic species a (or a source thereof), andWO_zthe source of (a).

WO_zThe source of (a) may comprise a tungsten (VI) species and a reducing agent, such as a reducing acid, such as lactic acid or citric acid, optionally lactic acid.

WO_zThe source of (A) may comprise tungstic acid, metatungstate, paratungstate or tungstate (WO)₄ ^2-). Tungstic acid may be provided, for example, by passing a tungstate salt through an ion exchange resin. WO_zMay also provide one or more of polyatomic species a and M. For example, sodium tungstate and ammonium metatungstate may be used to provide WO to be incorporated into materials_zAnd sodium and ammonium ions.

Optionally providing the monatomic material M (or source thereof), polyatomic material A (or source thereof), and WO in admixture under acidic conditions (at a pH of optionally not greater than 3, optionally not greater than 2.5, optionally not greater than 2, optionally not greater than 1.5, and optionally from 1.0 to 1.5)_zThe source of (a).

The method can include heating the blend to form a product. The blend can be heated for at least 5 hours, optionally at least 6 hours, optionally at least 10 hours, optionally at least 20 hours, optionally at least 30 hours, optionally at least 40 hours, optionally at least 50 hours, optionally at least 60 hours, and optionally at least 70 hours.

The method can include heating the blend for no more than 90 hours, optionally no more than 80 hours, optionally no more than 70 hours, optionally no more than 60 hours, optionally no more than 50 hours, and optionally no more than 40 hours.

The method may comprise heating the blend for 5 to 100 hours, optionally for 10 to 100 hours, optionally for 20 to 90 hours, and optionally for 40 to 80 hours.

The method may include heating the blend to a temperature of: at least 100 ℃, optionally at least 120 ℃, optionally at least 140 ℃, optionally at least 150 ℃, optionally at least 160 ℃, optionally at least 170 ℃, optionally at least 180 ℃, and optionally at least 190 ℃.

The method may include heating the blend to a temperature of: no more than 250 ℃, no more than 240 ℃, no more than 220 ℃, and optionally no more than 200 ℃.

The method may include heating the blend to a temperature of: 100 ℃ to 220 ℃, optionally 140 ℃ to 200 ℃, and optionally 150 ℃ to 190 ℃.

The product thus formed may be filtered and/or dried and/or heated in an inert atmosphere. The product thus formed is optionally filtered, dried and heated in an inert atmosphere. In this context, an inert atmosphere is an atmosphere that does not contain substantial amounts of oxygen, such as would oxidize one or more of the components of the material of formula (I). Heating in an inert atmosphere may include heating to the following temperatures: at least 100 ℃, optionally at least 200 ℃, optionally at least 300 ℃, optionally at least 400 ℃, and optionally at least 500 ℃. Heating in an inert atmosphere may include heating to the following temperatures: a temperature of no more than 800 ℃, optionally no more than 700 ℃, optionally no more than 600 ℃, optionally no more than 500 ℃, and optionally no more than 400 ℃. Heating in an inert atmosphere may include heating to the following temperatures: 100 ℃, -800 ℃ and optionally 100 ℃, -600 ℃. Heating in an inert atmosphere can include heating for up to 10 hours, optionally up to 8 hours, optionally up to 6 hours, optionally up to 4 hours, and optionally up to 2 hours. Heating in an inert atmosphere can include heating for at least 0.5 hours, and optionally heating for at least 1 hour. Heating in an inert atmosphere may include heating for 0.5 to 10 hours, 0.5 to 6 hours, and 0.5 to 4 hours.

According to a fourth aspect of the present invention there is provided a method of providing an object with infrared absorption capability, the method comprising providing to the object a material of formula (I).

The method of the fourth aspect of the invention may comprise providing to the object a composition according to the second aspect of the invention. The method may comprise providing the object with a liquid composition according to the second aspect of the invention, and then forming a solid composition from the liquid composition (e.g. by evaporating one or more components of the liquid composition).

Of course, it will be understood that features described in relation to one aspect of the invention may be incorporated into other aspects of the invention. For example, the methods of the invention may incorporate any of the features described with reference to the materials of the invention, and vice versa.

Drawings

Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawing (fig. 1), fig. 1 showing X-ray diffraction data for exemplary embodiments of tungsten oxide according to the present invention and comparative examples.

Detailed Description

The synthesis of exemplary embodiments of various materials of formula (I) according to the present invention will now be described.