Structural transition caused by pressure-induced valence change in Sm₄Bi₃ below 300 k

The P-T phase diagram for Sm₄Bi₃ was constructed by energy dispersive SR X-ray diffraction under pressure up to about 60 kbar at low temperature down to 35 K. The first kind pressure-induced valence transitions from mixed valence phases I and II to a pure trivalent high pressure phase III show a large positive slope dT/dP=46 deg/kbar and this slope does not change in sign with decreasing temperature as seen in SmS. This behavior is analysed by taking into account the magnetic and interconfiguration parts of entropy in each state.