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Red phosphor is indispensable to achieve warm white light in the white light diode (WLED) application. However, the current red phosphors suffer from high cost and harsh synthesis conditions. In this study, an oxide‐based rare‐earth‐free red‐emitting phosphor Li3Mg2NbO6:Mn4+ (LMN:Mn4+) has been successfully synthesized by a simple solid‐state reaction method. The relationship between crystal structure and luminescence was investigated in detail. The site occupancy of the doping Mn4+ ion in the LMN host has been discussed from the point of bond valence sum. How the coordination environment of doping Mn4+ affects the energy level of doping Mn4+ ion has been illustrated via the Tanabe‐Sugano energy‐level diagram. Moreover, warm white light has been obtained using LMN:Mn4+ as compensator to the YAG:Ce3+. [ABSTRACT FROM AUTHOR]

A novel apatite‐based UV‐excited dual‐emitting Ca2Na2La6(SiO4)4(PO4)2O: Eu2+/Eu3+ phosphor (CNL: Eu2+/Eu3+) was designed and successfully synthesized by a solid‐state reaction. Compared with previous reports on this family of materials, a structural study based on DFT calculation exhibited a new consequence that the monovalent ions in this system are more inclined to occupy the seven‐coordinate cationic sites rather than the nine‐coordinate sites. This result was confirmed by the structural refinement and high‐resolution transmission electron microscopy (HRTEM) data. Due to the coexistence of Eu2+ and Eu3+ dopants in the material, under 345 or 392 nm excitation, CNL: 0.02Eu2+/Eu3+ exhibited a green Eu2+ emission band (528 nm) and red Eu3+ emission peaks (around 618 nm). The application potential of CNL:0.02Eu2+/Eu3+ in luminescent thermometry was studied by exploiting the temperature sensitivity of the fluorescent intensity ratio (green/red) at different temperatures. It was found that, under 345 nm excitation, the fluorescent intensity ratio of CNL: 0.02Eu2+/Eu3+ displayed linear correlation over the temperature range of 298 to 473 K with a high sensitivity of 2.82%K−1. Additionally, the emission color of the CNL: 0.02Eu2+/Eu3+ sample under UV lamp (254 and 365 nm) excitation showed an obvious change (from green to red) as the temperature increased from 298 to 473 K (from green to red). These results indicated that CNL: Eu2+/Eu3+ can serve as an excellent visual luminescent ratiometric thermometer. Furthermore, this work provides a novel reference for developing high‐performance luminescence temperature‐sensing materials. [ABSTRACT FROM AUTHOR]

Using the solid-state reaction method, Ce3+, Tb3+-coactivated Si5 AlON7 ( Si6− z Al z O z N8− z, z = 1) phosphors were successfully synthesized. The obtained phosphors exhibit high absorption and strong excitation bands in the wavelength range of 240-440 nm, matching well with the light emitting-diode ( LED) chip. The ET from Ce3+ to Tb3+ ions in Si5 AlON7: Ce3+, Tb3+ has been studied and demonstrated by the luminescence spectra and decay curves. Moreover, the phosphors show tunable emissions from blue to green by tuning the relative ratio of the Ce3+ to Tb3+ ions. Thermal quenching properties of Si5 AlON7: Ce3+, Tb3+ had also been investigated and the quenching temperature is ~190°C. These results show that Si5 AlON7: Ce3+, Tb3+ could be a promising candidate for a single-phased color-tunable phosphor applied in UV-chip pumped LEDs. [ABSTRACT FROM AUTHOR]