We study the ferroelectric phase transition in PbSc1/2Nb1/2O3 (PSN) using a first-principles effective Hamiltonian approach. Results for PSN with NaCl-type ordering of Sc and Nb on the B sites shows that a Pb-centered effective Hamiltonian is appropriate for the ordered cell. We obtain a complete effective Hamiltonian for ordered PSN that has the form of effective Hamiltonians for simple perovskites. We modify the effective Hamiltonian to include the effects of Sc-Nb disorder by adding one additional term giving the effective force on the Pb site due to the nearest neighbor B-site cations. Monte Carlo simulations of our model shows that disordered PSN has a lower Curie temperature than ordered PSN, in agreement with a previous first-principles study based on a virtual crystal approach. No evidence for relaxor behavior is seen in our model.
Proceedings Title: Workshop on Fundamental Physics of Ferroelectrics | 11th | Fundamental Physics of Ferroelectrics 2001: 11th Williamsburg Workshop
Conference Dates: February 4-7, 2001
Conference Title: AIP Conference Proceedings
Pub Type: Conferences
dielectric permittivity, ferroelectric phase transitions, lead scandium niobate, PSN, relaxor ferroelectrics