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The thermal conductivity of molten silicon was measured by a hot-disk method in short-duration microgravity environments. The hot-disk sensor was made of molybdenum foil cut in a conducting pattern and covered with an aluminum nitride plate. Aluminum nitride has good resistivity against corrosion from silicon melt and the molybdenum foil was protected from the molten silicon. The thermal conductivity of molten silicon measured on the ground was estimated to be 45.6 W·m-1·K-1 at the melting point (1687 K). The thermal conductivity of molten silicon measured in microgravity was about 5% lower than that measured on the ground.

Thermal hysteresises of electrical resistance, accompanying with a structural phase transition, in epitaxial VO 2 films have been successfully reduced to 1°C or less by doping Ti or Nb ions. We considered that owing to the metal-ion-substitutive structural defects induced by doping metal ions into VO 2 films, the structural phase transition easily occurred without superheating or supercooling. In Nb-doped VO 2 films, the hysteresis disappeared at a lower doping level than Ti-doped VO 2 films. The maximum values of the temperature coefficient of the resistance of V 0.91 Ti 0.09 O 2 and V 0.982 Nb 0.018 O 2 films, which exhibited non-hysteretic MI transitions, were ¹24.8%/°C at 46°C and ¹21.6%/°C at 19°C, respectively.

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