Neutron and Light Scattering Studies of Nearly Stoichiometric Lithium Tantalate

The dynamical properties of the nearly stoichiometric LiTaO 3 crystals are studied by neutron scattering and light scattering. The neutron scattering shows the high value of the Curie temperature Tc which is the typical feature of near stoichiometry. In the broadband Brillouin scattering the intense quasielastic scattering is observed in the vicinity of Tc and the critical slowing down is clearly observed in the vicinity of Tc. As to the inelastic neutron scattering in the vicinity of Tc, we found that it behaves as expected for the critical scattering at a phase transition. In addition, we observed scattering with complex shape in the wavevector-energy space which is present in a very broad temperature and energy transfers range.