Abstract: Disclosed is a light emitting device employing non-stoichiometric tetragonal Alkaline Earth Silicate phosphors. The light emitting device comprises a light emitting diode emitting light of ultraviolet or visible light, and non-stoichiometric luminescent material disposed around the light emitting diode. The luminescent material adsorbs at least a portion of the light emitted from the light emitting diode and emits light having a different wavelength from the absorbed light. The non-stoichiometric luminescent material has tetragonal crystal structure, and contains more silicon in the crystal lattice than that in the crystal lattice of silicate phosphors having stoichiometric crystal structure. The luminescent material is represented as the formula (BauSrvCawCux)3?y(Zn,Mg,Mn)zSi1+bO5+2b:Euu. Light emitting devices having improved temperature and humidity stability can be provided by employing the non-stoichiometric tetragonal Alkaline Earth Silicate phosphors.

Abstract: The invention relates to a process for the preparation of phosphors of the formula I BawSrxCaySiO4:zEu2+??(I) where w+x+y+z=2 and 0.005?z?0.5, and to an illumination unit and to the use of the phosphor as LED conversion phosphor for white LEDs or so-called colour-on-demand applications.

Abstract: The invention relates to a process for the preparation of phosphors of the formula I BawSrxCaySiO4:zEu2+??(I) where w+x+y+z=2 and 0.005?z?0.3, and to an illumination unit and to the use of the phosphor as LED conversion phosphor for white LEDs or so-called colour-on-demand applications.

Abstract: Disclosed are non stoichiometric Copper Alkaline Earth Silicate phosphors activated by divalent europium for using them as high temperature stable luminescent materials for ultraviolet or daylight excitation. The phosphors are represented as the formula (BauSrvCawCux)3-y(Zn,Mg,Mn)zSi1+bO5+2b:Eua. The nonstoichiometric tetragonal silicate is prepared in a high temperature solid state reaction with a surplus of silica in the starting mixture. Furthermore, luminescent tetragonal Copper Alkaline Earth Silicates are provided for LED applications, which have a high color temperature range from about 2,000K to 8,000K or 10,000K showing a CRI with Ra=80˜95, when mixed with other luminescent materials.