Let the sulfur in: Sulfidomolybdates and -tungstates of alkaline earth and rare earth metals as promising host materials for luminescence applications

• Applicant: Professor Dr. Ingo Hartenbach
• Subject Area: Solid State and Surface Chemistry, Material Synthesis
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 527525135

The main focus of this project lies in the synthesis and characterization of alkaline earth and rare earth metal sulfidomolybdates and -tungstates. So far these classes of compounds have not been investigated, however, the aforementioned sulfidometallates exhibit the following properties, which render them very interesting for prospective luminescence applications: 1. Other than most sulfido-complexes, the respective molybdates and tungstates are not labile to hydrolysis, thus, they are stable to atmospheric influences. 2. The ligand-to-metal charge transfer (LMCT) within those units, which can be utilized as sensitizer to harvest and subsequently transferring energy to luminescent active cations present in those materials, resides in the range of visible light. The major workload in this proposal is represented by the syntheses of the alkaline earth and rare earth sulfidomolybdates and -tungstates. Therefore, different approaches will be used, which comprise solvochemical as well as hydrothermal techniques and even reactions in liquid hydrogen sulfide besides "classical" and mechanochemical solid-state methods. These first methods take place at drastically lower temperatures and those milder conditions promise a more energy efficient synthesis. Besides characterization via X-ray diffraction, vibrational spectroscopy and thermal analyses, the main focus lies in the optical properties of the synthesized products, which will be determined by photoluminescence- and diffuse reflectance spectroscopy. Thus, after successful and optimized syntheses of the alkaline earth and rare earth metal sulfidomolybdates and -tungstates as well as doping them with the appropriate luminescence active cations, these compounds should ideally emerge as luminescent materials that come close to application.

• DFG Programme: Research Grants