Characterization of electronic properties of novel materials is of great importance for exploratory materials development and also for the discovery of new correlated phases. As several novel compounds are available in powder form only, contactless methods, which also work on air-sensitive samples, are highly desired. We present that the microwave cavity perturbation technique is a versatile tool to study conductivity in such systems. The examples include studies on semiconducting–metallic crossover in carbon nanotubes upon alkali doping, study of vortex motion in the K3C60 superconductor, and the characterization of various alkali atom doped phases of black phosphorus.
