PHYSICAL-PROPERTIES OF A Y3AL5O12 MELT

Density, surface tension, contact angle (with an Ir wire) and viscosity data were measured for a Y3Al5O12 melt from 1970-degrees-C (just above the melting point) to 2070-degrees-C. Density, as determined by the Archimedean two bob technique, was 3.688 g/cm3 at the melting point, with a volume coefficient of thermal expansion of only 1.8 +/- 0.5 X 10(-5). The maximum bubble pressure method found the surface tension to be high, 781 dyn/cm at 1970-degrees-C, but also with a low temperature dependence. Data from these two measurements allowed determination of the contact angle of the melt with the iridium suspension wire to be approximately 113-degrees. The melt viscosity was 46 cP at the melting point and had an Arrhenius temperature dependence with an activation energy of only 15.3 kcal/mol. These data would account for a lack of convective and surface tension driven fluid flow that makes yttrium aluminum garnet melts appear quiescent.