A lighting device

A lighting device for adjusting the color temperature of white light emitted by a luminescent material, wherein the lighting device comprises:

• a luminescent material configured to emit white light when being exposed to electromagnetic radiation of a preselected wavelength range;
• at least one excitation unit configured to expose the luminescent material to electromagnetic radiation of a first wavelength range selected from the range of 230-330 nm;
• at least one excitation unit configured to expose the luminescent material to electromagnetic radiation of a second wavelength range, different from the first wavelength range, selected from the range of 300-600 nm;
• a metering unit configured to adjust the ratio of the irradiances of electromagnetic radiation of first wavelength range and of electromagnetic radiation of second wavelength range that is exposed on the luminescent material for adjusting the color temperature of white light emitted by the luminescent material as a result of being subjected to the electromagnetic radiation of the preselected wavelength range;
• wherein the luminescent 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 combination 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 of Tl, Pb, or Bi, or any combination of such cations, or wherein M″″ is absent;
• with the proviso that at least one of X and X′ is present.