High-pressure phase transitions in UP(1-x)S(x)
High-pressure X-ray diffraction using synchrotron radiation has been performed on UP(1-x)S(x)(x= 0.1; 0.25; 0.4) up to 53 GPa. UP(1-x)S(x) is a solid solution with a B1(NaCl) structure. For all compositions a second order phase transition is observed around 10 GPa. The phase formed can be described as a distorted B1 structure of rhombohedral symmetry. For UP(1-x)S(x) with x < 0.25 a second phase transition is observed, which takes place in the region of 35 GPa. This phase transition occurs when the nearest U-U distance reaches the Hill-limit of 330-340 pm. The high-pressure phase seems to have orthorhombic or even monoclinic symmetry. It has some similarities to the high pressure phase of UP. UP(6)S(4) shows only weak indications for an additional phase at 55 GPa. In conclusion, it is observed that the second phase transition and the bulk modulus B(0) in UP shift to higher pressure, when phosphorus is replaced by sulphur.
Bibliographic Reference: Paper presented: Third Workshop "Actinides under Pressure", Karlsruhe (DE), July 24-25, 1989
Availability: Available from (1) as Paper EN 35182 ORA
Record Number: 199010919 / Last updated on: 1994-12-01
Original language: en
Available languages: en