Thermoluminescent and superparamagnetic composite particle and marking comprising same

A composite particle for use in a marking, comprising:

• a thermoluminescent core consisting of two or more ceramic materials, each of the two or more ceramic materials doped with at least one ion selected from metal ions, transition metal ions and rare earth metal ions;
• a thermoconductive layer that covers the thermoluminescent core and comprises one or more of SiO2, TiO2, polymethylmethacrylate;
• and
• a superparamagnetic material being in the form of aggregated or single superparamagnetic particles distributed over a surface of the thermoconductive layer, wherein the superparamagnetic particles cover 1% to 70% of the surface of the thermoconductive layer;
• wherein each of the two or more ceramic materials is selected from the following:
• Ba2MgSi2O7, Ba2Si3O8, Ba2SiO, Ba2ZnSi2O7, Ba5SisO21, BaSi2O5, BaSiO3, CaGd2Si2O7, Li2CaSiO4, NaLaSiO4, BaAl10MgO17, BaAl12O19, BaHfO3, CaHf3, GdSc2Al3O12, Gd3Y3Al10O24, SrHfO3, YAlO3, Ba2B5O9Cl, Ba2Ca(BO3)2, Ba3Gd(BO)3, Ca4YO(BO3)3, CaLaB7O13, CaYBO4, GdB3O6, GdBO3, LaB3O6, Li6Gd(BO3)3, Li6Y(BO3)3, LuBO3, ScBO3, YAl3B4O12, AgGd(PO3)4, Ba2P2O7, Ba3(PO4)2, Ba3B(PO4)3, Ba3P4O13, Ba5(PO4)3F, BaKPO4, BaP2O6, Ca5(PO4)3F, CaBPO5, CeP5O14, CsGd(PO3)4, CsLuP2O7, CsYP2O7, K3Lu(PO4)2, KGd(PO3)4, LuP2O7, KYP2O7, LiCaPO4, LiGd(PO3)4, LuPO4, NaBaPO4, NaGd(PO3)4, NaLuP2O7, RbLuP2O7, RbYP2O7, Sr5(PO4)3F, Gd2S3, Lu2S3, and CaSnO3, each doped with the at least one ion selected from Eu2+, Eu3+, Dy3+, Pr3+, Sm3+, Tb3+, Ce3+, Ce2+, Er3+, Tm3+, Cr3+, Mn2+, Ti3+, and In3+;
• CaTiO3 doped with Pr3+ and In3+;
• and
• Ga2O3 doped with Cr3+;
• wherein the two or more doped ceramic materials are selected such that they provide distinct glow curves, wherein a glow curve of each of the two or more doped ceramic materials is obtained by plotting an intensity of radiation emitted by the ceramic material versus time of applying an oscillating magnetic field to the superparamagnetic material of the composite particle.