The Crystal Structure and Luminescence Behavior of Self-Activated Halotungstates Ba3WO5Cl2 for W-LEDs Applications

The self-activated halotungstate Ba₃WO₅Cl₂ was successfully synthesized using a high-temperature solid-state method. X-ray diffraction analysis (XRD) confirmed the formation of a single-phase compound with a monoclinic crystal structure, ensuring the material's purity and structural integrity. The luminescence properties of Ba₃WO₅Cl₂ were thoroughly investigated using both optical and laser-excitation spectroscopy. The photoluminescent excitation (PLE) and emission (PL) spectra, together with the corresponding decay curves, were recorded across a broad temperature range, from 10 K to 480 K. The charge transfer band (CTB) of the [WO₅Cl] octahedron was clearly identified in both the PL and the PLE spectra under ultraviolet light excitation, indicating efficient energy transfer within the material's structure. A strong blue emission could be detected around 450 nm, which is characteristic of the material's luminescent properties. However, this emission exhibited thermal quenching as the temperature increased, a common phenomenon where the luminescence intensity diminishes due to thermal effects. To better understand the thermal quenching behavior, variations in luminescence intensity and decay time were analyzed using a straightforward thermal quenching model. This comprehensive study of Ba₃WO₅Cl₂ luminescent properties not only deepens the understanding of its photophysical behavior but also contributes to the development of novel materials with tailored optical properties for specific technological applications.