Ab initio calculation of the ferroelectric phase transition in disordered and ordered PbSc{sub 0.5}Ta{sub 0.5}O{sub 3} and PbSc{sub 0.5}Nd{sub 0.5}O{sub 3} solid solutions with the use of a model Hamiltonian

Journal Article · Sat Mar 15 04:00:00 EDT 2008 · Journal of Experimental and Theoretical Physics

DOI:https://doi.org/10.1134/S1063776108030138· OSTI ID:21075588

To describe the ferroelectric phase transition in ordered and disordered PbSc{sub 0.5}Ta{sub 0.5}O{sub 3} (PST) and PbSc{sub 0.5}Nd{sub 0.5}O{sub 3} (PSN) solid solutions, a model Hamiltonian is written in the local-mode approximation, in which long-range dipole-dipole and short-range interactions of local modes are taken into account. The Hamiltonian parameters are determined from the set of energies of a series of distorted structures, calculated within the nonempirical generalized Gordon-Kim model. The statistical mechanics of the systems with a model Hamiltonian is investigated by the Monte Carlo method. It is revealed that PSN solid solutions undergo a transition to the ferroelectric rhombohedral phase through an intermediate phase, existing in a narrow temperature range. PST solid solutions undergo a ferroelectric phase transition directly from the paraelectric cubic to the ferroelectric rhombohedral phase.

• OSTI ID: 21075588
• Journal Information: Journal of Experimental and Theoretical Physics, Journal Name: Journal of Experimental and Theoretical Physics Journal Issue: 3 Vol. 106; ISSN JTPHES; ISSN 1063-7761
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
APPROXIMATIONS
DIPOLES
FERROELECTRIC MATERIALS
HAMILTONIANS
INTERACTION RANGE
MONTE CARLO METHOD
PHASE TRANSFORMATIONS
SOLID SOLUTIONS
STATISTICAL MECHANICS
TEMPERATURE DEPENDENCE