Liquidus range

The following discussion concerns the thermal liquidus ranges available in different ionic liquids, as functions of cation and anion structure and composition. In particular, those structural features of cation and anion that promote these properties (while providing other desirable, and sometimes conflicting characteristics of the liquid, such as low viscosity, chemical stability, etc.) and variations in liquidus ranges and stabilities are the focus of this chapter. 

Upper stage propellant applications are usually based primarily on performance—i.e., high specific impulse. If the upper stage is a multistart vehicle, hypergolicity is usually required. Careful consideration is also given to the propellant physical and chemical stability as well as to the matching of the propellant s liquidus range to the space environmental temperature if the propellant system is to remain operational in space... 

The Nd-Ag-Pb phase diagram has only been studied for the 0-33 at% Nd range at 870 K (Salamakha et al., 1996). Only the equiatomic plumbide NdAgPb has been reported. Similar behavior has been observed for the Nd-Zn-Pb system at 870 K (Salamakha et al., 1999a). Both systems reveal a liquidus range in the lead rich region at 870 K. Probably the isothermal sections at lower temperatures will reveal the existence of lead rich compounds. 

So far more than 180 rare earth-transition metal-plumbides have been reported. They crystallize with 23 different structure types. Apart from the few lead rich plumbides with YbsRlpSnis and related structures, only plumbides with 33 at% or even lower lead content have been reported. Some ternary systems exhibit large liquidus ranges in the lead rich regions at 870 °C. Through phase analytical investigations at lower temperatures one will certainly get access to new lead rich phases. In view of the more than 500 and 850 rare earth-transition metal-stannides and indides, respectively, the lead based systems certainly have a great potential for many more phases to be discovered. 

---