Phase transitions in the liquid-vapor interface of dilute alloys of Bi in Ga: New experimental studies

We report the results of measurements of x-ray reflectivity and grazing incidence x-ray diffraction from the liquid-vapor interfaces of four dilute alloys of Bi in Ga with mole fractions xBi =0.0032, 0.0023, 0.000 37, and 0.000 037. The monolayer coverage of the alloys with xBi =0.0023, and xBi =0.000 37 is about 0.85 and only very slightly temperature dependent. The monolayer coverage in the lowest-concentration alloy, with xBi =0.000 037, ranged from 0.82 at 29°C to 0.58 at 110°C. In none of these alloys, down to the lowest temperature used, 29°C, can we find any evidence for crystallization of the Bi monolayer that segregates as the outermost stratum of the liquid-vapor interface. Drawing on theoretical arguments we propose that the transitions inferred from the second-harmonic generation and plasma generation studies of dilute Bi in Ga alloys are from the liquid state to the hexatic state of the Bi monolayer. The data for the alloy with xBi =0.000 037 suggest that near 80°C there is a disordered phase-to-disordered phase transition. © 2005 American Institute of Physics.

Duke Scholars

Author Xu Jiang Fuqua School of Business