Modern magnetic resonance approaches for characterizing rare-earth containing glasses and glass ceramics

Rare-earth containing glasses are important materials with technologically relevant combinations of mechanical and optical properties. For developing their functional materials potential it is important to understand the local environment and spatial distribution of the rare-earth ions and their influence upon the structural organization of the glassy matrix. Nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) can furnish crucial information about these aspects. In this review we describe the relevant theoretical foundations with a particular focus on rare-earth containing systems. Important experimental approaches covered include dipolar NMR, paramagnetically perturbed NMR, EPR, and hyperfine interaction spectroscopies. These are illustrated in the context of various case studies, including (1) structural features of rare-earth aluminosilicate glasses, (2) spatial distribution and clustering of rare-earth dopants, (3) rare-earth ligand distributions in fluoride phosphate glasses, and structural changes along the glass-to-ceramic transformation in (4) aluminoborate and (5) oxyfluoride glasses. (AU)