Structural phase transition of potassium under high-pressure and low-temperature condition

We performed electrical resistance and powder X-ray diffraction measurements of potassium under high-pressure and low-temperature condition. In the temperature dependence of resistance under several pressure, no superconducting transition was observed below 1 K. From the powder X-ray diffraction measurement, the K-III phase, it has a host-guest structure, is stable in wide pressure range. Furthermore, the K-IV phase disappeared and the amorphous-like region with no X-ray diffraction peaks appeared at low temperature below 150 K.