Synthesis
One heating cycle in the Faraday apparatus suffices to prepare Th3P4 (a subphosphide ThP0.6 also exists). The reactants are heated for 60 hours in a furnace with a 940/450°C gradient (atomic ratio of Th:P = 1:3). The absorptivity of Th for x-rays isvery high, and therefore minute quantities of surface oxide interferein the x-ray pattern analysis. Therefore, for precision work(particularly when the product is a lower phosphide) an emptycylindrical crucible is first heated for one hour (under high vacuum)in the rear section of the tubular quartz reactor, while the smallquartz flask with the raw material at the front end of the reactorremains cold. After cooling of the rear section (in high vacuum),the raw material is transferred to the crucible and the reactortube is sealed off.
