https://doi.org/10.1351/goldbook.S05597
Any transition from a semiconductor to a metallic state under the influence of a temperature or pressure change or both. Examples:
- Ti2O3: band-edge crossing in a semiconductor to semimetal transition.
- SmS: localized level crossing a band edge. In SmS hydrostatic pressure above the critical pressure
broadens the Sm-5d band to make the band edge cross the Sm- level. - A localized-itinerant transition.
- A switching transition.