| Research Abstract |
This work has been carried out to develop basic technologies and informations for production of single crystals having higher melting point, finacially suportedby 2-years grant-in-aid for scientific research. Especially, research projects are focussed to examine reactions between the melt and container materials, and also to measure the physicochemical properties as the surface tension and the density. Samples used in this work are LiF, NaF, KF, MgF_2, CaF_2, SrF_2, BaF_2, GaF_3, NdF_3, LaF_3 as fluorides, Al_2O_3, Ti_2O_3 as single component oxides, and LuNbO_3, LiTaO_3, CaO・Al_2O_3 and BaO ・ Ti_2O_3 as binary oxides. If melting point of a compound is below 1873K, container materials used were mainly platium and plainum-rhodium alloy, which showed to be stable to the melts. However, if the melting point is above 1873K, molybdenum was used as the container. In the case, it was observed that small amount of molybdenum dissolved into LiTaO_3, and BaO ・ Ti_2O_3 melts, even if the melts were kept under an atmosphere having lower oxygen potential. The other oxide melts can be kept stablely under the atmosphere. Two types of furnaces were used to measure the surface tensions and densities. One is a molybdenum winding furnace and another is a induction heating furnace. The Archimedean method was used for measurements of the densities, and the maximum bubble pressure method was used for measurements of the densities and surface tensions of melts having higher melting points. From the measurenents, physico-chemical properties were analyzed and discussed.
From the results, technology for choise of container materials and also for measurements of densities and surface tensions of the melts were established to produce single crystals of the compounds having higher melting points up to 2400K.
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