"Role of the lattice in the gamma ->alpha phase transition of Ce: A high-pressure neutron and X-ray diffraction study"
I.K. Jeong, T.W. Darling, M.J. Graf, T. Proffen, R.H. Heffner, Y. Lee, T. Vogt, J.D. Jorgensen
Physical Review Letters
Vol.92, No.10, pp.10570, 2004.03
The temperature and pressure dependence of the thermal displacements and lattice parameters were obtained across the γ→α phase transition of Ce using high-pressure, high-resolution neutron and synchrotron x-ray powder diffraction. The estimated vibrational entropy change per atom in the γ→α phase transition, ΔSγ−αvib≈(0.75±0.15)kB, is about half of the total entropy change. The bulk modulus follows a power-law pressure dependence that is well described using the framework of electron-phonon coupling. These results clearly demonstrate the importance of lattice vibrations, in addition to the spin and charge degrees of freedom, for a complete description of the γ→α phase transition in elemental Ce.