Abstract
The Raman spectra of LaAl, PrAl, and NdAl have been observed at temperatures from 10 to 1135°K. Each of these materials evidences a nominally second-order trigonal cubic phase transition; that in LaAl has previously been analyzed by other workers on the basis of x-ray, EPR, and inelastic neutron scattering; however, evidence for the transitions in PrAl [at (1320±20)°K] and NdAl [at (1640±30) °K] is presented here for the first time. In each material, the phase transition is due to the collapse of the mode at the point of the high-temperature cubic Brillouin zone. Modes associated with and are observed in the trigonal phase in each crystal.
- Received 3 February 1969
DOI:https://doi.org/10.1103/PhysRev.183.823
©1969 American Physical Society