Apparent Temperatures Measured at Melting Points of Some Metal Oxides in a Solar Furnace

Six metal oxides (A1 2 O 3 , TiO 2 , Nb 2 O 5 , Ta 2 O 5 , La 2 O 3 , and Dy 2 O 3 ) were melted in a solar furnace and the apparent temperatures at their melting points were measured by means of a conventional optical pyrometer. The apparent temperatures of three of them (A1 2 O 3 , TiO 2 , and Nb 2 O 5 ) were 2025°, 1840°, and 1496°C. respectively, in close agreement with the melting points as determined by other investigators using other methods. The apparent temperatures of the other three varied widely and bore no relation to their melting points. The method therefore does not have general utility for the measurement of unknown melting points.