PHASE RELATIONS AND STRUCTURES OF PROTACTINIUM HYDRIDES
The present study was initiated after suitable quantities of 231-Pa (0.052 mass % impurity) were prepared in our institute 3-. Temperature - pressure - composition data were measured with a gold lined Seivert's apparatus in the experimental range 373 < T < 795 K and 10 mubar < P < 45 bar. Metal samples (0.15 - 0.21 g) were contained in a W cell. Samples for X-ray studies were prepared along hybriding and dehydriding isotherms and were cooled at constant composition. Diffraction data were obtained by the Debye-Scherrrer method. The pressure - composition isotherms measured during hydriding and dehydriding are similar, but large hysteresis effects are encountered. Results of extensive studies indicate that equilibrium is defined by the dehydriding pressures. At low H/Pa, hydrogen dissolves in the bct metal to form phase I. The hydrogen saturated metal coexists with hydride for H/Pa < 1.3. Isotherms for T > 500 K show that the phase II exists across the range 1.3 <= H/Pa <= 1.7, and that a second diphasic region occurs for 1.7 < H/Pa < 2.0. Phase III forms in the range 2.0 <= H/Pa <= 3.0. At T < 500 K, a continuous solid solution designated phase IV exists across the entire range 1.3 <= H/Pa <= 3.0.
Bibliographic Reference: 1ST INTERNATIONAL CONFERENCE ON THE CHEMISTRY AND TECHNOLOGY OF THE LANTHANIDES AND ACTINIDES, VENEZIA (ITALY), SEPT. 5-10, 1983 - WRITE TO CEC LUXEMBOURG, DG XIII/A2, POB 1907 MENTIONING PAPER E 31200 ORA
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Record Number: 1989122031700 / Last updated on: 1987-01-01
Available languages: en