Here we report on a series of experiments that use high power lasers to ramp compress aluminum al up to 475 gpa. Point maximum of aluminum at 3500 gpa and 20000 k. The polymorph distribution and the symmetry evolution of al at 150 gpa are quite similar to that of cu which reflects a pressure mediated transformation of the crystallization pathway of al. Energy budget and core envelope motion in common envelope evolution. Measurement of body centered cubic aluminum at 475 gpa phys. The solid solid al phase transformations fcc hcp and hcp bcc are observed at 216 9 gpa and 321 12 gpa respectively with the bcc phase persisting to 475 gpa.
119 175702 2017 article in physical review letters 1202 january 2018 with 60 reads how we measure reads. Measurement of body centered cubic aluminum at 475 gpa article in physical review letters 11917 october 2017 with 97 reads how we measure reads. Raman signal from the diamond anvil or x ray signal from the rhenium gasket allow measurement of pressure. Which also undergoes re entrant melting though at the much higher pressure of 300 gpa. Nanosecond in situ x ray diffraction and simultaneous velocimetry measurements were used to determine the crystal structure and pressure respectively of ramp compressed aluminum at stress states between 111 and 475 gpa. Chamandy luke yisheng tu eric g blackman jonathan carroll nellenback adam frank baowei liu and jason nordhaus.
Measurement of body centered cubic aluminum at 475 gpa phys. When the lattice stress is released entirely the orthorhombic phase can further transform into a body centered tetragonal structure. Measurement of body centered cubic aluminum at 475 gpa. Under this quasi isentropic compression al remains in the solid state and two solidsolid phase transformations are observed. Measurement of body centered cubic aluminum at 475 gpa d phys. The original body centered cubic bcc phase transfers to an orthorhombic phase at 106 gpa during compression at room temperature and the orthorhombic phase remains stable up to 40 gpa.
In this case the fcc crystal of al at 15 gpa is 6 denser than liquid which is quite close to the solid liquid density difference of al at 0 gpa. In situ x ray diffraction is performed to detect the crystal structure.