Lattice Dynamics of Disordered Perovskite Pb(Zn_<1/3>Nb_<2/3>)O_3 : Condensed Matter: Structure, etc.

概要

論文の詳細を見る
Inelastic-neutron-scattering experiments were performed to investigate the phonon-dispersion relations in the cubic relaxor Pb(Zn_<1/3>Nb_<2/3>)O_3. The transverse acoustic (TA) phonon branches have flat and isotropic dispersion curves. The zone-boundary [ζζ0]-TA_2 phonon energy is approximately 6 meV, considerably lower than the values reported for simple perovskites. The low-Iying transverse optical (TO) branches drop sharply with decreasing ζ, similar to the behavior observed for the complicated system Pb(Zn_<1/3>Nb_<2/3>)_<0.92>Ti_<0.08>. The constant-Q scans reveal the absence of the well-defined TO phonon spectra in the range 0 ≤ ζ ≤ 0.1, in contrast with the sharp TA spectra. The TA, TA_2 and TO phonon energies at ζ = 0.1 and 0.2 decrease with increasing temperature up to 673 K. The phonon hardening toward the transition temperature contradicts the usual soft mode behavior in simple perovskites.
社団法人日本物理学会の論文
2001-06-15