BAO-1/2Y2O3-CUOX EUTECTIC MELTING IN AIR

Eutectic melting in the BaO-1/2Y2O3-CuOx system has been investigated, using three different compositions. Thermal events up to 1100-degrees-C were studied by means of differential thermal analysis/thermogravimetric analysis (DTA/TGA). Phase formation and compositions of melts were examined using powder X-ray diffraction and scanning electron microscopy/energy-dispersive X-ray spectrometry (SEM/EDS) of quenched experiments. The eutectic occurs at 923-degrees +/- 10-degrees-C in CO2- and H2O-scrubbed air, and the eutectic melt has a Ba:Y:Cu cation ratio of 23.2(+/-0.5): 0.5(+/-0.1):76.3(+/-1.0). The oxygen content of the quenched eutectic melt, as determined by hydrogen reduction, indicated that nearly all of the copper in the melt was present as Cu+. A topological sequence, based on the X-ray results, is presented which describes the events immediately following melting.