TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (Claimed): Preparation of (I) comprises: mixing at least one salt containing europium, at least one salt comprising at least one of beryllium, magnesium, calcium, strontium, barium or zinc, at least one salt comprising at least one of boron, aluminum, gallium, indium, thallium, scandium yttrium, lanthanum, cerium, gadolinium, or lutetium, at least one salt comprising at least one of vanadium, niobium, tantalum, arsenic, antimony or bismuth at a predetermined molar ratio; optionally grinding the mixture; performing a primary heat treatment on the mixture at 800-1300 degrees C under an oxidative atmosphere; and performing a secondary heat treatment on the mixture at 1200-1700 degrees C under a reductive atmosphere. Preferred Components: (I) is of formula (M22-xM3M5O6:Eu2+) (c1) or (M22-x(M1aa-bM2ab)M5O6:Eu2+) (c2).x = greater than 0 to less than or equal to 2, preferably greater than 0 to less than 0.3;M1a, M2a = B, Al, Ga, In, TI, Sc, Y, La, Ce, Gd, or Lu, where M1a is not equal to M2, preferably M1a is In;a = greater than 0 to less than or equal to 1;b = greater than or equal to 0 to less than 1, preferably 0; anda+b = 1.The salts comprise oxides, halides, hydrogen sulfates, or carbonates. The primary light source is a luminescent indium aluminum gallium nitride, and/or indium gallium nitride. SPECIFIC COMPOUNDS - 6 Compounds (I) are disclosed e.g. strontium-europium-indium-tantalum oxide of formula (Sr1.92Eu0.08InTaO6), barium-europium-indium-tantalum oxide of formula (Ba1.92Eu0.08InTaO6), strontium-europium-indium-vanadium oxide of formula (Sr1.92Eu0.08InVO6), strontium-europium-indium-niobium oxide of formula (Sr1.92Eu0.08InNbO6) and strontium-europium-indium-antimony oxide of formula (Sr1.92Eu0.08InSbO6).    EXAMPLE - 7.985 g Indium oxide, 17.680 g strontium carbonate, 13.223 g tantalum oxide, 0.211 g europium(III) oxide were weighed and mixed using a speed mixer at 1800 rpm for 5 minutes. The resulting mixture was fired at 1100 degrees C in air for 8 hours. The resulting powder was grounded and fired a second time at 1500 degrees C for 4 hours under argon. The resulting raw product was grounded and sieved to obtain strontium-europium-indium-tantalum oxide (Sr1.92Eu0.08InTaO6).