Luminescent material

A method of securely identifying an item comprising, incorporating on the item a security device selected from a group consisting of a thread, a foil, a hologram or an ink, wherein the security device comprises a material represented by the following formula (I)

• (M′)8(M″M′″)6O24(X,X′)2:M″″
• formula (I)
• wherein
• M′ represents a monoatomic cation of an alkali metal selected from Group 1 of the IUPAC periodic table of the elements, or any combination of such cations;
• M″ represents a trivalent monoatomic cation of an element selected from Group 13 of the IUPAC periodic table of the elements, or of a transition element selected from any of Groups 3-12 of the IUPAC periodic table of the elements, or any combi-nation of such cations;
• M′″ represents a monoatomic cation of an element selected from Group 14 of the IUPAC periodic table of the elements, or of an element selected from any of Groups 13 and 15 of the IUPAC periodic table of the elements, or of Zn, or any combination of such cations;
• X represents an anion of an element selected from Group 17 of the IUPAC periodic table of the elements, or any combination of such anions, or wherein X is absent;
• X′ represents an anion of an element selected from Group 16 of the IUPAC periodic table of the elements, or any combination of such anions, or wherein X′ is absent;
• and
• M″″ represents a dopant cation of an element selected from transition metals of the IUPAC periodic table of the elements, or any combination of such cations;
• with the proviso that at least one of X and X′ is present;
• wherein the security device when exposed to light of a first wavelength emits at least part of the received energy as light at a second wavelength which is longer than the first wavelength.

A method of medical imaging a body fluid or tissue of a human or animal, the method comprising:

• introducing a material into a body fluid or tissue of a human or animal, wherein the material is represented by the following formula (I)
• (M′)8(M″M′″)6O24(X,X′)2:M″″
• formula (I)
• wherein
• M′ represents a monoatomic cation of an alkali metal selected from Group 1 of the IUPAC periodic table of the elements, or any combination of such cations;
• M″ represents a trivalent monoatomic cation of an element selected from Group 13 of the IUPAC periodic table of the elements, or of a transition element selected from any of Groups 3-12 of the IUPAC periodic table of the elements, or any combi-nation of such cations;
• M′″ represents a monoatomic cation of an element selected from Group 14 of the IUPAC periodic table of the elements, or of an element selected from any of Groups 13 and 15 of the IUPAC periodic table of the elements, or of Zn, or any combination of such cations;
• X represents an anion of an element selected from Group 17 of the IUPAC periodic table of the elements, or any combination of such anions, or wherein X is absent;
• X′ represents an anion of an element selected from Group 16 of the IUPAC periodic table of the elements, or any combination of such anions, or wherein X′ is absent;
• and
• M″″ represents a dopant cation of an element selected from transition metals of the IUPAC periodic table of the elements, or any combination of such cations;
• with the proviso that at least one of X and X′ is present;
• and
• exposing the material to light of a first wavelength causing it to emit at least part of the received energy as light at a second wavelength which is longer than the first wavelength,

A medical diagnostic method comprising;

• introducing a material to a human or animal, vivo or to a body fluid or tissue sample, wherein the material is represented by the following formula (I)
• (M′)8(M″M′″)6O24(X,X′)2:M″″
• formula (I)
• wherein
• M′ represents a monoatomic cation of an alkali metal selected from Group 1 of the IUPAC periodic table of the elements, or any combination of such cations;
• M″ represents a trivalent monoatomic cation of an element selected from Group 13 of the IUPAC periodic table of the elements, or of a transition element selected from any of Groups 3-12 of the IUPAC periodic table of the elements, or any combi-nation of such cations;
• M′″ represents a monoatomic cation of an element selected from Group 14 of the IUPAC periodic table of the elements, or of an element selected from any of Groups 13 and 15 of the IUPAC periodic table of the elements, or of Zn, or any combination of such cations;
• X represents an anion of an element selected from Group 17 of the IUPAC periodic table of the elements, or any combination of such anions, or wherein X is absent;
• X′ represents an anion of an element selected from Group 16 of the IUPAC periodic table of the elements, or any combination of such anions, or wherein X′ is absent;
• and
• M″″ represents a dopant cation of an element selected from transition metals of the IUPAC periodic table of the elements, or any combination of such cations;
• with the proviso that at least one of X and X′ is present;
• and
• exposing the material to light of a first wavelength causing it to emit at least part of the received energy as light at a second wavelength which is longer than the first wavelength.