Preparation, Electronic Structure, and Photoluminescence Properties of Eu[sup 2+]-Activated Carbonate Sr[sub 1−x]Ba[sub x]CO[sub 3] for White Light-Emitting Diodes

The carbonate phosphors were prepared by a modified solid-state reaction. The electronic structure of was calculated using the CASTEP code. The result shows that has an indirect energy gap of about 4.3 eV, which agrees with the experimentally determined value (about 4.4 eV). In addition, the photoluminescence properties of -doped have been studied carefully. The phosphors show a strongly broad-band absorption in the range of 390–600 nm and emit a broad luminescence band in the range of 550–750 nm with a maximum peak at 618 nm. With the replacement of by , the position of the maximum emission peak shifts from 618 to 750 nm, and the chromaticity index of shifts correspondingly from (0.633, 0.366) to (0.673, 0.326). Therefore, the phosphor can be well matched with the blue-emitting GaN chip to compensate the red color deficiency of commercial phosphor yttrium aluminum garnet -based white light-emitting diodes or to create white light by combining with a blue chip and another green phosphor.