Characterization of the fcc-distorted fcc-structural transition in lanthanum in an extended pressure and temperature range

Abstract

The displacive transition in La is studied in the pressure range up to 26 GPa and under temperatures up to 630 K with angular dispersive X-ray diffraction at the ESRF and with energy dispersive X-ray diffraction in HASYLAB to elucidate further details of this transition with an extension of the transition line up to 22.5(5) GPa and 590(10) K and a determination of the order parameter down to a level of η ≈=5· 10^?4.