Supraleitung, elektrischer Widerstand und strukturelle Eigenschaften des Lanthans unter Druck

Abstract

High precision resistivity measurements of lanthanum between 300 K and liquid helium temperature under pressures up to 200 kbar reveal anomalies both in theresidual and the phonon resistivity. The transition temperature to the superconducting state, T$_{c}$ increases with pressure, showing anomalies at about 25 and about 53 kbar. T$_{c}$ reaches a limiting value of 12.9 K just under 200 kbar. Our measurements indicate two new first-order crystallographic phase transitions at low temperatures. A tentative T-P phase diagram is constructed suggesting that it is possibly isomorphic to that of cerium. In addition, the phase transition of AgCl occuring at room temperature and 76 kbar was followed down to 4 K and 52 kbar