PREPARATION AND SINGLE-CRYSTAL GROWTH OF PROTOACTINIUM ARSENIDES BY CHEMICAL VAPOR TRANSPORT

Single crystals of protactinium arsenides (PaAs2, Pa3As4 and PaAs) were prepared from the elements by chemical vapour transport using iodine as transporting agent. In a van Arkel process the protactinium arsenides were deposited on an induction-heated tungsten support. Depending on the compounds, deposition temperatures ranged from 1000 to 2200 °C; the quartz bulb was kept at 400 - 450°C. The single-phase deposits were identified and characterized by X-ray diffraction methods. The values of the lattice parameters, compared with the values of the corresponding compounds of the actinide series, are discussed in terms of delocalization of the 5f electrons. © 1979.