DIFFERENT RESULTS FOR THE EQUILIBRIUM PHASES OF CERIUM ABOVE 5 GPA

The phases of cerium above 5 GPa have been studied using angle-dispers ive powder diffraction techniques. The phase obtained between 5 and 12 GPa at room temperature with filings of Ce has a monoclinic, distorte d-fcc structure with four atoms in a C-face-centered unit cell. Heatin g to 373 K for many hours yields the known alpha-U phase. With a singl e cut piece as a sample, the alpha-U phase is obtained at room tempera ture.