Positive and negative electrocaloric effect in BaTiO${}_3$ in the presence of defect dipoles

Abstract

The influence of defect dipoles on the electrocaloric effect (ECE) in acceptor doped BaTiO${}_3$ is studied by means of lattice-based Monte-Carlo simulations. A Ginzburg-Landau type effective Hamiltonian is used. Oxygen vacancy-acceptor associates are described by fixed defect dipoles with orientation parallel or anti-parallel to the external field. By a combination of canonical and microcanoncial simulations the ECE is directly evaluated. Our results show that in the case of anti-parallel defect dipoles the ECE can be positive or negative depending on the density of defect dipoles. Moreover, a transition from a negative to positive ECE can be observed from a certain density of anti-parallel dipoles on when the external field increases. These transitions are due to the delicate interplay of internal and external fields, and are explained by the domain structure evolution and related field-induced entropy changes. The results are compared to those obtained by MD simulations employing an {\it{ab initio}} based effective Hamiltonian, and a good qualitative agreement is found. In addition, a novel electrocaloric cycle, which makes use of the negative ECE and defect dipoles, is proposed to enhance the cooling effect.

References in corpus (5)

• Giant electrocaloric effect around T${}_c$
• Decisive role of oxygen vacancy in ferroelectric vs. ferromagnetic Mn-doped BaTiO3 thin films
• First principles-based calculation of the electrocaloric effect in BaTiO${}_3$: comparison between direct and indirect methods
• First-principles accurate total-energy surfaces for polar structural distortions of BaTiO3, PbTiO3, and SrTiO3: consequences to structural transition temperatures
• Influence of defects on ferroelectric and electrocaloric properties of BaTiO${}_3$

Cited by in corpus (10)

• Electric field induced phase transition and electrocaloric effect in PMN-PT
• The electrocaloric effect in BaTiO${}_3$ at all three ferroelectric transitions: anisotropy and inverse caloric effects
• Polarizing oxygen vacancies in insulating metal oxides under high electric field
• State transition and electrocaloric effect of BaZr${}_x$Ti${}_{1-x}$O${}_3$: simulation and experiment
• Electrocaloric effects in the lead-free Ba(Zr,Ti)O${}_3$ relaxor ferroelectric from atomistic simulations
• Charge effects in donor doped perovskite ferroelectrics
• Polarization rotation and the electrocaloric effect in barium titanate
• Understanding doped perovskite ferroelectrics with defective dipole model
• Tailoring the electrocaloric effect by internal bias fields and field protocols
• Determination of optimal reversed field with maximal electrocaloric cooling by a direct entropy analysis