Transition Metal and rare-earth ion doped glasses and glass-ceramics are viewed as the new generation of luminescent photonic materials. Besides having superior thermal and mechanical properties than crystals, these materials can incorporate higher concentrations of doping ions and be fabricated at lower cost, in a larger variety of sizes and shapes. To optimize the luminescent properties of these materials, detailed structural information regarding the local environment of the rare-earth species is essential. While solid state nuclear magnetic resonance (NMR) is in general a promising tool for such purposes, unfortunately, the rare-earth ions themselves cannot be studied by NMR due to their paramagnetism. To overcome this difficulty, we propose to develop a comprehensive magnetic resonance strategy, comprising three complementary approaches: (i) NMR study of probe nuclei 45Sc, 89Y, 139La, 171Yb, and 175Lu, associated with diamagnetic "mimics" of the fluorescent species. (ii) analysis of the paramagnetic interactions of framework nuclei with the luminophores and (iii) examination of the magnetic dipolar interactions of the unpaired electrons with nearby nuclear spins, using electron spin echo envelope modulation (ESEEM) and electron nuclear double resonance (ENDOR) spectroscopies. This strategy will help to elucidate structural aspects of TM and RE doped glasses, such as: (i) the influence of the RE species on the structural organization of the glassy framework, (ii) the RE ion local environments, (iii) the connectivity of the RE ion species with the network former species, (iv) the overall spatial distribution of the rare-earth dopants, and (v) the structural aspects of the glass to glass ceramic transition.
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