The PIs will investigate the elastic wave velocity, Vp, and attenuation, Qp-1, in pure melts of Fe and Fe-Ni-S alloys which are relevant to the outer core of the earth. By using the ultrasonic interferometric technique, the temperature, compositional and frequency dependences of Vp-1 will be determined in the frequency range from 3 to 20 MHz and in the temperature range from 988oC to 1650oC. Bulk modulus and viscosity will also be calculated. By characterizing any relaxation mechanisms, the results should prove very valuable criteria with which to interpret existing shock-wave elasticity data on pure Fe. In addition, these results will be analysed from the point of view of liquid structure. The static structure factor will be calculated and compared to previous experimental and theoretical values. The influence of parent solid structure on liquid structure will be investigated and interpreted in terms of its geophysical significance.
