Single-axis acoustic levitation of the heaviest solid (iridium, $\rho =22.6\mathrm{g}\mathrm{c}{\mathrm{m}}^{\mathrm{-}\mathrm{3}}$) and liquid (mercury, $\rho =13.6\mathrm{g}\mathrm{c}{\mathrm{m}}^{\mathrm{-}\mathrm{3}}$ on the Earth is achieved by greatly enhancing both the levitation force and stability through optimizing the geometric parameters of the levitator. The acoustically levitated Pb-Sn eutectic alloy melt ($\rho =8.5\mathrm{g}\mathrm{c}{\mathrm{m}}^{\mathrm{-}\mathrm{3}}$) is highly undercooled by up to 38 K, which results in a microstructural transition of “lamellae—broken lamellae—dendrites.” The drastic enhancement of levitation capability indicates a broader application range of single-axis acoustic levitation.

• Received 16 January 2002

DOI:https://doi.org/10.1103/PhysRevLett.89.104304