Determination of zinc melting curve to 4.3 GPa by ultrasonic measurements in a cubic press

In this study, we have determined the melting curve of zinc up to 4.3 GPa using improved in situ ultrasonic measurements in a cubic press. The temperature gradient in the cell was calculated based on a finite element temperature field using a simplified two-dimensional axisymmetric numerical mode. Cell pressures in the cubic press have been also determined by means of ultrasonic measurements based on the known melting curve of lead. The high-pressure melting transition was identified through characteristic discontinuities in ultrasonic travel times within the sample. Thanks to the careful metrology of temperature correction, the melting temperature was determined with uncertainty of less than 10 ℃. Our experimental result of zinc melting curve shows excellent agreement with theoretical predictions and is consistent with most previous high-pressure experimental data. These findings demonstrate that ultrasonic measurements in the cubic press provide a reliable and practical method for determining high-pressure melting curves and phase boundaries of materials.