*Article* **Measurements of Density of Liquid Oxides with an Aero-Acoustic Levitator**

**Sergey V. Ushakov 1,\*, Jonas Niessen 2,\*, Dante G. Quirinale 3,\*, Robert Prieler 2, Alexandra Navrotsky 1 and Rainer Telle 2**


**Abstract:** Densities of liquid oxide melts with melting temperatures above 2000 ◦C are required to establish mixing models in the liquid state for thermodynamic modeling and advanced additive manufacturing and laser welding of ceramics. Accurate measurements of molten rare earth oxide density were recently reported from experiments with an electrostatic levitator on board the International Space Station. In this work, we present an approach to terrestrial measurements of density and thermal expansion of liquid oxides from high-speed videography using an aero-acoustic levitator with laser heating and machine vision algorithms. The following density values for liquid oxides at melting temperature were obtained: Y2O3 4.6 ± 0.15; Yb2O3 8.4 ± 0.2; Zr0.9Y0.1O1.95 4.7 ± 0.2; Zr0.95Y0.05O1.975 4.9 ± 0.2; HfO2 8.2 ± 0.3 g/cm3. The accuracy of density and thermal expansion measurements can be improved by employing backlight illumination, spectropyrometry and a multi-emitter acoustic levitator.

**Keywords:** levitation; rare earth oxides; zirconia; hafnia; melting; thermodynamics
