Investigation of transition metal oxides by ultrasonic microscopy

Ultrasonic microscopy is now well established in non-destructive testing and has become a versatile method for investigating solid materials. It may serve both as imaging technique for large scale inspection of sample homogeneity and also as measuring device for a local determination of elastic properties. Our investigations of single crystalline vanadium dioxide nicely demonstrate this capability of flexible use and are exemplary for the beneficial effect of ultrasonic microscopy on materials research, in general. Here we focus on three different subjects: the detection of odd phases in as-grown single crystals, the inspection of structural transformations accompanying the metal–insulator transition and the investigation of elastic properties performed on small crystallites.