Markers of a material's thermal history, method for marking the material, and method for verifying its thermal history

Abstract

Thermal History Markers of a Material, Method for Marking the Material, and Method for Verifying its Thermal History. The present invention relates to the use, as a thermal history marker of a material, of at least one coordination polymer of formula [Lnx(ligand)y(H2O)z]∞ in which: Ln is terbium and / or europium, optionally doped by at least one of lanthanum, yttrium, gadolinium, and lutetium; x is 1 or 2, where Ln represents terbium, europium, or both; (ligand)y represents 1 to 3 ligands of Ln, each ligand consisting of a benzene ring independently substituted at least once by at least one of: -B(OH)2, -B(OH)3-, -PO32-, -PO3H-, and -Cl-, and optionally also substituted at least once. by –COO- ;y is 1 to 3 ; etz is 0 to 10.

Description

Title of the invention: Markers for the thermal history of a material, method for marking the material and method for verifying its thermal history

[0001] The present invention relates to markers of the thermal history of a material, to a method of marking the material and to a method of verifying the thermal history of the marked material.

[0002] Recent crises have accelerated awareness of the need for traceability of materials throughout their life cycle. Some materials are particularly sensitive to temperature and can lose their properties when subjected to excessive heat. It is therefore essential to be able to verify afterward that they retain all of their properties and have not been thermally degraded. It is well known that some medications or active ingredients can lose their effectiveness when subjected to excessively high temperatures, but other materials can also be affected.

[0003] Of course, when temperature is an important parameter it is monitored but, most often, this monitoring is carried out globally (temperature of the storage shed, for example) and does not ensure that a particular product has not been exposed to an excessive temperature.

[0004] Mass doping, at very low doping levels, of the material or its packaging with a luminescent coordination polymer could constitute a solution to this problem.

[0005] A coordination polymer is a one-, two-, or three-dimensional compound in which ions of transition elements (3d or 4f) are linked together by ligands. EW Berg; A. Alam, Studies on coordination polymers. Part I: Coordination polymers of 8,8'-dihydroxy-5,5'-biquinolyl. Anal. Chim. Acta 1962, 27, 454-459.

[0006] The present invention therefore primarily relates to the use, as a marker of the thermal history of a material, of at least one coordination polymer of formula [Lnx(ligand)y(H2O)z]œ in which: • Ln is terbium and / or europium possibly doped by at least one of lanthanum, yttrium, gadolinium and lutetium; • x is 1 or 2 that Ln represents terbium, europium or a mixture of the two; • (ligand)y represents 1 to 3 ligands of Ln, the or each ligand being made up of a benzene ring independently substituted at least once by at least one of: -B(OH)2, -B(OH)3, -PO32, -PO3H, -Cl and -COO; • y is 1 to 3; and • z is 0 to 10.

[0007] (ligand) can be selected from: • OOC-C6H4-B(OH)2, the substituents -COO and -B(OH)2 being preferably in para of each other; • OOC-C6H4-B(OH)3, the substituents -COO and -B(OH)3 being preferably in para of each other; • 2 O3P-C6H4-PO3H, the -PO32 and -PO3H substituents preferably being in para each other; 2 O3P-C6H5; • HO3P-C6H5; • (OOC)2-C6C14, the two -COO substituents preferably being ortho one on the other hand; and • (OOC)3-C6H3, two -COO substituents preferably being ortho of the first substituent -COO.

[0008] In particular, the coordination polymer may be at least one of the following: • [Ln(OOC-C6H4-B(OH)3)(H2O)2.(OOC-C6H4-B(OH)2)]00, Ln can be doped by yttrium, gadolinium and / or lutetium; • [Ln(O3P-C6H5)(HO3P-C6H5)]œ Ln can be doped by lanthanum, the ga dolinium, yttrium and / or lutetium; • [Ln2((OOC)2-C6Cl4)3(H2O)6]œ, Ln can be doped with yttrium and / or ga dolinium; and • [Ln((OOC)3-C6H3)(H2O)5.3,5H2O]œ, Ln can be doped with yttrium and / or lutetium.

[0009] The present invention also relates to a material containing at least one marker as defined above.

[0010] In one embodiment, the material may consist of a thermoplastic or thermosetting polymeric organic matrix, in which the marker(s) is or are contained in particular at a rate of 1 to 20 mg per kg.

[0011] In another embodiment, the material may consist of a mineral matrix such as concrete, in which the marker(s) is or are contained in particular at a rate of 1 to 20 mg per kg.

[0012] The invention also relates to a method for marking a material which is as defined above and of which it is to be determined, at a given time in its life, whether it has been subjected to a temperature greater than a given temperature T, characterized by the fact that at least one marker which exhibits a luminescence under UV characteristic of this temperature is incorporated into this material during its manufacture.

[0013] The invention also relates to a method for detecting whether a material such as prepared above has undergone during its life a thermal event which has led it above a given temperature T, characterized by the fact that the said material is irradiated at a UV excitation wavelength, the luminescence is measured over the entire visible spectrum from 400 to 800 nm to obtain a luminescence spectrum which is compared to standard luminescence spectra of the marker considered as a function of temperature.

[0014] The following examples illustrate the present invention without however limiting its scope.

[0015] Example 1: [Ln(OOC-C6H4-B(OH)3)(H20)2.(OOC-C6H4-B(OH)2)]00

[0016] Fig. 1 shows projection views of the crystal structure of the compound of the title in which Ln = Tb. Synthesis

[0017] The compounds in the title have been synthesized as described in the publications: • A. Abdallah; S. Freslon; X.Fan; A. Rojo; C. Daiguebonne; Y. Suffren; K. Bernot; G. Calvez; T. Roisnel; O. Guillou, Lanthanide based coordination polymers with 1,4 carboxyphenylboronic ligand: multi emissive compounds for multi sensitive luminescent thermometry probes. Inor g. Chem. 2019, 58, 462-475; • X.Fan; S. Freslon; C. Daiguebonne; L. Le Polies; G. Calvez; K. Bernot; O. Guillou, A family of lanthanide based coordination polymers with boronic acid as ligand. Inorg. Chem. 2015, 54, 5534-5546.

[0018] The synthesized compounds contain the lanthanides indicated in Table 1 below:

[0019] [Tables] Tb Eu 1-1 1 0 1-2 0 1 1-3 0.9 0.1 Crystallographic data

[0020] Table 2 below presents the crystallographic data of compound 1-1.

[0021] [Tables2] Molecular formula TbOnC14H17B2 Molecular weight 541.82 g.mol1 Crystal system Orthorhombic Space group Pbca (No. 61) Lattice parameters a = 8.5704 (1) Å b = 19.5441 (1) Å c = 21.4191 (3) Å Lattice volume 3587.71 (7) Å3 Z 8 Calculated density 1.98 g.cm3

[0022] Cambridge Crystallographic Data Center (CCDC) - 962513 X-ray diffraction

[0023] Fig. 2 shows the powder X-ray diffraction patterns of compounds 1-1, 1-2 and 1-3.

[0024] These diagrams demonstrate that compounds 1-1, 1-2 and 1-3 all have the same structure. In particular, the heterodilanthanide compound (compound 1-3) is isostructural to the homonuclear compounds based on terbium (compound 1-1) and europium (compound 1-2). Thermogravimetric analysis

[0025] Thermogravimetric analysis (TGA) of compound 1-1 was carried out under a synthetic air atmosphere between ambient temperature and 950°C, with a heating ramp of 5°C / min. The resulting curve is shown in [Fig. 3]: the analysis shows an initial release of 4 water molecules below 200°C, a plateau up to approximately 450°C, followed by progressive decomposition of the ligand.

[0026] Figure 4 shows the X-ray diffraction pattern obtained on the residual powder at the end of the thermal analysis and indicates that the final compound obtained is TbBO3. The X-ray diffraction pattern of the TbBO3 compound was simulated from the reference R. Velchuri et al. Materials Research Bulletin 46 (2011) 1219-1226.

[0027] Heat treatments - Luminescence properties

[0028] Compounds 1-1 and 1-3 were subjected to different heat treatments under the following conditions: • heating up to the set temperature at a rate of 5°C / min; • 5-minute temperature plateau; then • natural descent to ambient temperature.

[0029] The luminescence properties of the compounds were studied.

[0030] For this purpose, the emission spectra under UV irradiation (Xexc = 288 nm) of compounds 1-1 and 1-3 were measured as a function of the heat treatment plateau temperature.

[0031] Fig. 5 shows the emission spectra of compound 1-1 after heat treatment as a function of the temperature of the heat treatment plateau.

[0032] Fig. 6 shows the emission spectra of compound 1-3 after heat treatment as a function of the temperature of the heat treatment step.

[0033] Figures 5 and 6 show that compounds that have undergone different heat treatment exhibit different luminescence properties that are easily identifiable.

[0034] It is accepted that spectroscopic measurements depend on the apparatus used. To avoid this pitfall, it is possible to use compounds containing two different lanthanide ions simultaneously. The luminescence of these two ions does not change identically during dehydration or crystalline phase changes. Measuring the ratio of the intensities of the characteristic peaks of each ion thus eliminates the need for specialized equipment.

[0035] The intensity ratio of the major peak attributable to europium (615 nm) and the major peak attributable to terbium (545 nm) was calculated for compound 1-3 at each of the heat treatment plateau temperatures.

[0036] Figure 7 shows these peak ratios as a function of the plateau temperature.

[0037] Figure 8 shows the colorimetric coordinates of the thermally modified samples These treatments, calculated based on emission spectra, allow for the unambiguous identification of the heat treatment undergone by the sample.

[0038] Example 2: ^(OsP-CeHsj^OsP-CeHs)]^

[0039] Fig. 9 shows a projection view of the crystal structure of the compound of the title in which Ln = La. Synthesis

[0040] An aqueous solution of sodium phenylphosphonic acid (1 mmol in 10 mL of water) is added to an aqueous solution of lanthanide chloride (0.5 mmol in 10 mL). After 24 hours, the precipitate is filtered, rinsed with water, and air-dried (the yield is approximately 90%).

[0041] The synthesized compounds contain the lanthanides indicated in Table 3 below:

[0042] [Tables3] Tb Eu 2-1 1 0 2-2 0 1 Crystallographic data

[0043] Table 4 below presents the crystallographic data of the compound [La(O3 P-C6H5)(H03P-C6H5)]co.

[0044] [Tables4] Molecular formula LaP2Ci2HnO6 Molecular weight 452.07 g.mol1 Crystal system triclinic Space group Pl (no. 2) Lattice parameters a = 8.410 (3) Å b = 15.696 (7) Å c = 5.636 (1) Å a = 90.24 (3) ° [3 = 108.99 (1) ° y = 85.59 (4) ° Lattice volume 701.3 (4) Å3 Z 2 Calculated density 2.141 g.cm3

[0045] CCDC: 1190447

[0046] Ren-Chain Wang et al. Chemistry of Materials 1992, 4, 864-971 X-ray diffraction

[0047] Figure 10 shows the powder X-ray diffraction patterns of compounds 2-1 and 2-2.

[0048] These diagrams demonstrate that compounds 2-1 and 2-2 have the same structure. Thermogravimetric analysis

[0049] Thermogravimetric analysis (TGA) of compound 2-1 was carried out under a synthetic air atmosphere between ambient temperature and 950°C, with a heating ramp of 5°C / min. The resulting curve is shown in [Fig. 11]: the analysis shows an initial gradual and moderate mass loss (5%) below 350°C followed by an abrupt decomposition of the ligand around 400°C. The microcrystalline powder recovered at the end of the analysis corresponds to the compound TbPO4, as can be seen in the X-ray diffraction pattern in [Fig. 12], the pattern for the compound EuPO4 being simulated from the reference DF Mullica et al. / Inorganica Chimica Acta 109 (1985) 105-110.

[0050] Heat treatments - Luminescence properties

[0051] Compounds 2-1 and 2-2 were subjected to different heat treatments under the following conditions: • heating up to the set temperature at a rate of 5°C / min; • 2-hour temperature plateau; then • natural descent to ambient temperature.

[0052] The luminescence properties of the compounds were studied.

[0053] For this purpose, the emission spectra under UV irradiation (Xexc = 272 nm) of compounds 2-1 and 2-2 were measured as a function of the heat treatment plateau temperature.

[0054] Fig. 13 shows the emission spectra of compound 2-1 after heat treatment as a function of the heat treatment plateau temperature.

[0055] Fig. 14 shows the emission spectra of compound 2-2 after heat treatment as a function of the heat treatment plateau temperature.

[0056] Figures 13 and 14 show that compounds that have undergone different heat treatment exhibit different luminescence properties that are easily identifiable.

[0057] Example 3: [Ln^OOC^-CeCl^fLO)^

[0058] Fig. 15 shows a perspective view of the crystal structure of the compound of the title in which Ln = Y. Synthesis

[0059] An aqueous solution of sodium tetrachlorophthalic acid (0.75 mmol in 10 mL of water) is added to an aqueous solution of lanthanide chloride (0.5 mmol in 10 mL) heated to 80°C. After 24 hours under reflux, the precipitate is filtered, rinsed with water and air dried (the yield is approximately 90%).

[0060] The synthesized compounds contain the lanthanides indicated in Table 5 below:

[0061] [Tables5] Tb Eu 3-1 2 0 3-2 0 2 3-3 1.6 0.4 Crystallographic data

[0062] Table 6 below presents the crystallographic data of the compound [Y2 ((OOC^-CeChmO)^.

[0063] [Tableauxô] Molecular formula Y2C112O18C24H12 Molecular weight 1179.49 g.mol1 Crystal system monoclinic Space group P21 / c (No. 14) Lattice parameters a = 6.2155 (2) Å b = 19.6652 (7) Å c = 30.3720 (9) Å [3 = 94.63 (0) ° Lattice volume 3700.22 (37) Å3 Z 4 Calculated density 2.11715 g.cm3 X-ray diffraction

[0064] Fig. 16 shows the powder X-ray diffraction patterns of compounds 3-1, 3-2 and 3-3.

[0065] These diagrams demonstrate that compounds 3-1, 3-2 and 3-3 have the same structure as compound [Y2((OOC)2-C6C14)3(H2O)6]oo. Thermogravimetric analysis

[0066] Thermogravimetric analysis (TGA) of compound 3-2 was carried out under a synthetic air atmosphere between ambient temperature and 950°C, with a heating ramp of 5°C / min. The resulting curve is shown in [Fig. 17]: the analysis shows an initial mass loss corresponding to the departure of the coordination water molecules below 200°C, followed by a plateau up to 400°C and then an abrupt decomposition of the ligand. The microcrystalline powder recovered at the end of the analysis corresponds to the EuCIO compound, as can be seen in the X-ray diffraction pattern in [Fig. 18], the pattern of the EuCIO compound being simulated from the reference H. Bämighausen et al. / Zeitschrift für anorganische und allgemeine Chemie 338 (1965) 250-265.

[0067] Heat treatments - Luminescence properties

[0068] Compounds 3-2 and 3-3 were subjected to different heat treatments under the following conditions: • heating up to the set temperature at a rate of 5°C / min; • 5-minute temperature plateau; then • natural descent to ambient temperature.

[0069] The luminescence properties of the compounds were studied.

[0070] For this purpose, the emission spectra under UV irradiation (Xexc = 300 nm) of compounds 3-2 and 3-3 were measured as a function of the heat treatment plateau temperature.

[0071] Fig. 19 shows the emission spectra of compound 3-2 after heat treatment as a function of the temperature of the heat treatment plateau.

[0072] Fig. 20 shows the emission spectra of compound 3-3 after heat treatment as a function of the temperature of the heat treatment plateau.

[0073] Figures 19 and 20 show that compounds that have undergone different heat treatment exhibit different luminescence properties that are easily identifiable.

[0074] The intensity ratio of the major peak attributable to europium (615 nm) and the major peak attributable to terbium (545 nm) was calculated for compound 3-3 at each of the heat treatment plateau temperatures.

[0075] Figure 21 shows these peak ratios as a function of the plateau temperature.

[0076] Figure 22 shows the colorimetric coordinates of the thermally modified samples These treatments, calculated based on emission spectra, allow for the unambiguous identification of the heat treatment undergone by the sample.

[0077] Example 4: [Ln(OOC)3-CÆ3)(H2O)5.3.5HÆ

[0078] Fig. 23 shows a projection view of the crystal structure of the compound of the title in which Ln = Er. Synthesis

[0079] An aqueous solution of the sodium salt of 1,3,5-benzenetricarboxylic acid (0.5 mmol in 10 mL of water) is added to an aqueous solution of lanthanide chloride (0.5 mmol in 10 mL). After 10 minutes, the precipitate is filtered, rinsed with water, and air-dried (the yield is approximately 90%).

[0080] The synthesized compound contains the lanthanides indicated in Table 7 below:

[0081] [Table 7] Y Eu 4-1 0.8 0.2 Crystallographic data

[0082] Table 8 below presents the crystallographic data of the compound [Er(00C)3-C6H3)(H20)5.3,5H20]co.

[0083] [Tables8] Molecular formula ErCgH17Oi45 Molecular weight 527.5 g.mol1 Crystal system Monoclinic Space group C2 / c(No. 15) Lattice parameters a = 14.7496 (15) Å b = 16.9874 (15) Å c = 14.4591 (14) Å [3 = 118.754 (9) ° Lattice volume 3173.96 (100) Å3 Z 8 Calculated density 2.208 g.cm3

[0084] CCDC: 101659

[0085] C. Daiguebonne et al. Inorganica Chimica Acta 1999, 284, 139-145 X-ray diffraction

[0086] Figure [Fig. 24] shows the powder X-ray diffraction patterns of compound 4-1.

[0087] These diagrams demonstrate that compound 4-1 has the same crystal structure as the reference compound. Thermogravimetric analysis

[0088] Thermogravimetric analysis (TGA) of compound 4-1 was carried out under a synthetic air atmosphere between ambient temperature and 950°C, with a heating ramp of 5°C / min. The resulting curve is shown in [Fig. 25]: the analysis shows an initial mass loss corresponding to the departure of the coordination water molecules below 200°C, followed by a plateau up to 400°C and then an abrupt decomposition of the ligand. The microcrystalline powder recovered at the end of the analysis corresponds to the compound [Yi 6EuO4O3], as can be seen on the X-ray diffraction diagram of [Fig.26], the diagram of the compound being Y2O3 simulated from the reference Baldinozzi, G., Berar, J.-F., Calvarin, G., Mater.Sci.Forum (1998), 278-281, 680.

[0089] Heat treatments - Luminescence properties

[0090] Compound 4-1 was subjected to various heat treatments under the following conditions: • heating up to the set temperature at a rate of 5°C / min; • 5-minute temperature plateau; then • natural descent to ambient temperature.

[0091] The luminescence properties of the compound were studied.

[0092] For this purpose, the emission spectra under UV irradiation (Xexc = 312 nm) of compound 4-1 were measured as a function of the heat treatment plateau temperature.

[0093] Fig. 27 shows the emission spectra of compound 3-2 after heat treatment as a function of the temperature of the heat treatment step.

[0094] Fig. 27 shows that compounds that have undergone different heat treatment exhibit different luminescence properties that are easily identifiable.

[0095] Example 5: Marking of a polyvinylidene fluoride (PVDF) part with the compound IL3)[Tboj9Euoji(OOC-C6H4-B(OH)3)(H2O)2.(OOC-C6H4-B(OH)2)]O0 Sample preparation.

[0096] The compound 1-3 prepared as described in Example 1 is dispersed in a mixture of PVDF (150 mg) and DMF (2 mL) at room temperature. The suspension is then placed in an oven (80°C) for evaporation. A colorless film is finally obtained (sample 5-1).

[0097] Heat treatments and luminescence properties.

[0098] Sample 5-1 was subjected to various heat treatments under the following conditions: • heating up to the set temperature at a rate of 5°C / min; • 5-minute temperature plateau; then • natural descent to ambient temperature.

[0099] The luminescence properties of this sample were studied.

[0100] For this purpose, the emission spectra under UV irradiation (Xexc = 288 nm) of sample 5-1 were measured as a function of the heat treatment plateau temperature.

[0101] Fig. 28 shows the emission spectra of sample 5-1 after heat treatment as a function of the heat treatment plateau temperature.

[0102] Based on these emission spectra, the colorimetric coordinates were calculated. They are shown in [Fig.29].

[0103] Figures 28 and 29 show that PVDF samples doped with compound 1-3 and having undergone different heat treatment exhibit different luminescence properties that are easily identifiable.

[0104] Example 6: Marking of a polyvinylidene fluoride (PVDF) part with the compound (3-3) [Tblj6Eu0j4(OOC)2-C6Cl4)3(H2O)6]oo Sample preparation.

[0105] The compound 3-3 prepared as described in Example 3 is dispersed in a mixture of PVDF (150 mg) and DMF (2 mL) at room temperature. The suspension is then placed in an oven (80°C) for evaporation. A colorless film is finally obtained (sample 6-1).

[0106] Heat treatments and luminescence properties.

[0107] Sample 6-1 was subjected to various heat treatments under the following conditions: • heating up to the set temperature at a rate of 5°C / min; • 5-minute temperature plateau; then • natural descent to ambient temperature.

[0108] The luminescence properties of this sample were studied.

[0109] For this purpose, the emission spectra under UV irradiation (Xexc = 300 nm) of sample 6-1 were measured as a function of the heat treatment plateau temperature.

[0110] Fig. 30 shows the emission spectra of sample 6-1 after heat treatment as a function of the heat treatment plateau temperature.

[0111] Based on these emission spectra, the colorimetric coordinates were calculated. They are shown in [Fig.31].

[0112] Figures 30 and 31 show that PVDF samples doped with compound 3-3 and having undergone different heat treatment exhibit different luminescence properties that are easily identifiable.

[0113] Example 7: Marking of a part made of acrylic polymethyl methacrylate with the compound (3-3) [Tbi.eEuoXOOCh-CeCLûîCIWjeL Sample preparation.

[0114] The compound 3-3 prepared as described in Example 3 is dispersed in a mixture of PMMA (40 mg) and chloroform (CC13) (2 mL) at room temperature. The suspension is then left to evaporate in air. A colorless film is finally obtained (sample 7-1).

[0115] Heat treatments and luminescence properties.

[0116] Sample 7-1 was subjected to various heat treatments under the following conditions: • heating up to the set temperature at a rate of 5°C / min; • 5-minute temperature plateau; then • natural descent to ambient temperature.

[0117] The luminescence properties of this sample were studied.

[0118] For this purpose, the emission spectra under UV irradiation (Xexc = 300 nm) of sample 7-1 were measured as a function of the heat treatment plateau temperature.

[0119] Fig. 32 shows the emission spectra of sample 7-l after heat treatment as a function of the heat treatment plateau temperature.

[0120] Based on these emission spectra, the colorimetric coordinates were calculated. They are shown in [Fig.33].

[0121] Figures 32 and 33 show that PMMA samples doped with compound 3-3 and subjected to different heat treatment exhibit lumi- different nescences easily identifiable.

Claims

Claims

1. - Use, as a marker of the thermal history of a material, of at least one coordination polymer of formula [Lnx(ligand)y(H2O)z L in which: • Ln is terbium and / or europium optionally doped with at least one of lanthanum, yttrium, gadolinium and lutetium; • x is 1 or 2 whether Ln represents terbium, europium or a mixture of the two; • (ligand)y represents 1 to 3 ligands of Ln, the or each ligand consisting of a benzene ring independently substituted at least once by at least one of: -B(OH)2, -B(OH)3, -PO32, -PO3H, -Cl and -COO; • y is 1 to 3; and • z is 0 to 10.

2. - Use according to claim 1, characterized in that (ligand) is chosen from: • OOC-C6H4-B(OH)2, the substituents -COO and -B(OH)2 being preferably para to each other; • OOC-C6H4-B(OH)3, the substituents -COO and -B(OH)3 being preferably para to each other; • 2 O3P-C6H4-PO3H, the substituents -PO32 and -PO3H being preferably para to each other; 2 O3P-C6H5; • HO3P-C6H5; • (OOC)2-C6C14, the two substituents -COO being preferably ortho to each other; and • (OOC)3-C6H3, two -COO substituents preferably being ortho to the first -COO substituent.

3. - Use according to one of claims 1 and 2, characterized by the coordination polymer being at least one of • [Ln(OOC-C6H4-B(OH)3)(H20)2.(OOC-C6H4-B(OH)2)]00, Ln being able to be doped with yttrium, gadolinium and / or lutetium; • [LnXOsP-CeHsXHOsP-CeHs)]», Ln can be doped with lanthanum, gadolinium, yttrium and / or lutetium; • ILmOOOCh-CGCUUHoOkU- Ln can be doped with yttrium and / or gadolinium; and • [Ln((OOC)3-C6H3)(H2O)5.3,5H2O]oo, Ln can be doped with yttrium and / or lutetium.

4. - Material containing at least one marker as defined in one of claims 1 to 3.

5. - Material according to claim 4, characterized in that it consists of a thermoplastic or thermosetting polymeric organic matrix, in which the marker(s) is(are) contained in an amount in particular of 1 to 20 mg per kg.

6. - Material according to claim 5, characterized in that it consists of a mineral matrix such as concrete, in which the marker(s) is or are contained in an amount in particular of 1 to 20 mg per kg-

7. - Method for marking a material which is as defined in one of claims 4 to 6 and of which it is desired to know, at a given moment in its life, whether it has undergone a temperature higher than a given temperature T, characterized by the fact that at least one marker is incorporated into this material, during its manufacture, which exhibits(s) a luminescence under UV characteristic of this temperature.

8. - Method for detecting whether a material as prepared in claim 7 has undergone during its life a thermal event which has brought it above a given temperature T, characterized in that said material is irradiated at a UV excitation wavelength, the luminescence is measured over the entire visible spectrum from 400 to 800 nm to obtain a luminescence spectrum which is compared to standard luminescence spectra of the marker considered as a function of temperature.

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