Surface Tensions and Densities of Molten Al₂O₃, Ti₂O₃, V₂O₅ and Nb₂O₅

Abstract

Surface tensions and densities of molten Al₂O₃, Ti₂O₃, V₂O₅ and Nb₂O₅ were determined accurately by the maximum bubble pressure method. The measurements were carried out under Ar+10%H₂ for molten Al₂O₃ and Ti₂O₃, and under air for molten V₂O₅ and Nb₂O₅. Surface tension and density of molten Al₂O₃ near the melting point are 606±6 mN m^-1 and 3.06±0.03×10³ kg m^-3, and those of molten Ti₂O₃ are 584±5 mN m^-1 and 3.91±0.03×10³ kg m^-3, respectively. The temperature coefficient of surface tension of molten V₂O₅ is slightly positive value of 0.0111 mN m^-1 K^-1, while for molten Nb₂O₅ it is negative value of -0.0596 mN m^-1 K^-1. This suggests that the network structure of molten V₂O₅ changes with temperature. The temperature coefficient of density of molten V₂O₅ is very low. The results are discussed in comparison with those of other molten pure oxides and fluorides having high melting points.