The presence and effect of martensitic embryos in potassium

Abstract

Martensitic transitions occur in Li and Na at low temperatures. In Li the structure produced in the 9R ( delta -Sm structure). For K the martensite clearly does not occur in bulk, but there is corroborative evidence from much transport, thermodynamic and structural data which would support an embryonic martensitic presence. There also exists optical microscope evidence that RB can undergo some conversion, but above all there exists neutron diffraction evidence for K that the system shows an appropriate two-phase character up to 90K at least, at the level of about 1 part in 10⁴. The model of a precursor martensitic state appears more consistent with experiment and theory than the CDW model supported by Overhauser and co-workers (1983).