Nuclear magnetic resonance study of the cubic-to-tetragonal phase transition in BaTiO3

摘要: Abstract 47,49 Ti and 137 Ba NMR measurements were performed on single-domain pure BaTiO 3 crystals between room temperature 1700 K. In the tetragonal phase ( T c ≈ 400 K), lines show a dependent quadrupole shift Δν Q associated with electrical polarization P s . Relating , underlying electric field gradient is found to be proportional square of order parameter. The variation shown fit Landau's relation first-order transitions. observed nuclear spin relaxation rates consist three contributions: A classical phonon contribution, diffusion-induced contribution above due motion oxygen vacancies, in vicinity related transition. From latter, correlation time dynamics transition was determined.