Solid‐state NMR of Heterogeneous Materials

Most solid matrials are hetorogeneous on a microscopic or a microscopic scale, or both. Examoles of hetrogeneties are the phase structure of incompatible polymers, pores in ceramics, distributions in mechanical stress, variations in molecular order and mobility of extruded polymers, and chemical composition in composite materials. Nuclear magnetic resonance (NMR) spectroscopy has unique capabilities for detailed characterization of such hetrogeneities: Microscopic structures between 1 nm and 200 nm can be investigated in spin‐diffusion studies, whereas macroscopic structures above 10 μm can be analyzed in imaging experiments.