Cryogenic propane source of cold neutrons

Propagating vibrational modes in the Zr–Be metallic glasses

“…The high-energy band (multiplied by a factor of 10 for clarity) is represented by a peak with the center of gravity varying as a function of momentum transfer. Similar to the previous results on VDOS for Ni-B [5,6] and Zr-Be [7], the low-energy band (below 25 meV) can be associated with motions involving Zr-Zr bonds, while the high-energy band (25-60 meV) corresponds to the modes in which mostly the light Be atoms are moving. Apart from that, an additional lowenergy mode (∼5 meV) arises and increases in intensity with increasing Be atom content.…”

“…By analogy with many-component crystalline matter, metallic glasses should possess 'acoustic-phonon like' and 'optic-phonon like' vibrational excitations. In the case of the Ni 1−x B x system, for which the ratio of atomic masses is higher (m Ni /m B = 5.3) than for Mg 70 Zn 30 , Ni 67 Zr 33 or Ni 62 Nb 38 , the density of vibrational states is divided in two distinct parts which can be attributed to 'acoustic' and 'optic' modes [5,6]. The system Zr-Be is most suitable for investigation of the dispersion of 'acoustic' and 'optic' modes.…”

Temperature dependence of the phonon entropy of vanadium

“…A recent measurement of the phonon DOS of vanadium at ambient conditions 7 was undertaken with little complication, and many previous measurements have been performed with generally good success. [8][9][10][11][12][13][14][15][16][17][18][19][20] Using similar techniques, we measured the phonon DOS of vanadium at 293, 873, 1273, and 1673 K. We assess the thermal broadening of the phonon DOS, and interpret it as phonon-lifetime broadening. We also assess the temperature dependence of the phonon DOS in terms of the phonon softening predicted under thermal expansion.…”