Developed vanadium-system glass
Although lead-system glass has been used as low-temperature sealing glass up until now, in recent years, bismuth-system low-melting-point glass (which does not contain harmful lead) has been used. However, as for bismuth, the issues of environmental preservation and resource scarcity remain. Consequently, securing a stable supply of bismuth is a common concern. Under this circumstance, vanadium-system glass-which is promising in terms of low thermal expansion and low-temperature application-has been developed.
Controlling glass structure by controlling valency of vanadium
Conventional vanadium-system glass is an unstable material that has a strong moisture-absorption characteristic; namely, it is dissolved by atmospheric moisture. By changing the valency of vanadium from five to four, however, its three-dimensional structure can be changed to a denser one, thereby drastically improving its air-tightness and moisture resistance.
Moreover, varying the proportion of four- and five-valency vanadium enables the movement of electrons to be controlled. Accordingly, exploiting this phenomenon, a technique for controlling electrical conductivity has been developed.
