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Herein, a new red phosphor Rb2TaF7:Mn4+was prepared by the co-precipitation method. Under excitation of the blue light at 468 nm, this phosphor exhibits a series of red-emitting peaks, due to the 2E→4A2transitions of Mn4+. It is worth mentioning that an intense zero-phonon line (ZPL) of Mn4+appears at 620 nm in this non-equivalent Mn4+doping system. A white light-emitting diode (w-LED) based on the Rb2TaF7:Mn4+(1.0 mol%) phosphor emits bright white light with a color temperature (Tc) of 4387 K and a color rendering index (Ra) of 88, showing its potential application in w-LEDs.

Herein, a new red-emitting phosphor K3HfF7:Mn4+ was successfully synthesized. The crystal structure and morphology were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Mn4+ in K3HfF7 exhibits excellent luminescent properties with red emission at [?]630 nm and broad excitation band around [?]460 nm. The white light-emitting diode fabricated with K3HfF7:Mn4+ red phosphor shows intense warm white light with appropriate optical properties, the correlated color temperature of 3535 K and color rendering index of 86.2.

New phosphors, Sr3Al2O5Cl2 co-doped with Eu2+ and Bi3+, were prepared by solid state reaction technique, and their photoluminescent properties were investigated. Introducing Bi3+ ion broadened the excitation band of the phosphor Sr3Al2O5Cl2: Eu2+ and enhanced the emission intensity of Eu2+ under 400 nm excitation. The yellow LEDs were fabricated by combining InGaN-chips with Sr2.8Al2O5Cl2: 0.20Eu2+ and Sr2.7Al2O5Cl2:0.20Eu2+, 0.10Bi3+, intense yellow light can be observed by naked eyes. The phosphor Sr2.7Al2O5Cl2:0.20Eu2+, 0.10Bi3+ may be applied in fabrication of phosphor-converted light-emitting diodes (LEDs).

Red-emitting phosphor Na2SiF6:Mn4+was synthesized by a simple exchange process in H3PO4. Its crystal structure and morphology were characterized. Na2SiF6:Mn4+with single phase exhibits intense emission with the strongest peak at ∼ 627 nm. The emission energy from Na2SiF6:Mn4+is observed to be obviously higher than those from A2SiF6:Mn4+(A = K, Rb and Cs). This sample also has an excellent thermal quenching behavior. The present red-emitting phosphor was used for the fabrication of white light-emitting diodes and found to show good optical properties with color temperature of 3821 K and color rendering index of 94.4).