arXiv subjects

Zhijun Jiang

Publications and source records attributed to Zhijun Jiang.

20 records · Page 2Linked to original sources

arXiv2017

Electrocaloric effects in the lead-free Ba(Zr,Ti)O$_{3}$ relaxor ferroelectric from atomistic simulations

Atomistic effective Hamiltonian simulations are used to investigate electrocaloric (EC) effects in the lead-free Ba(Zr$_{0.5}$Ti$_{0.5}$)O$_{3}$ (BZT) relaxor ferroelectric. We find that the EC coefficient varies non-monotonically with the field at any temperature, presenting a maximum that can be traced back to the behavior of BZT's polar nanoregions. We also introduce a simple Landau-based model that reproduces the EC behavior of BZT as a function of field and temperature, and which is directly applicable to other compounds. Finally, we confirm that, for low temperatures (i.e., in non-ergodic conditions), the usual indirect approach to measure the EC response provides an estimate that differs quantitatively from a direct evaluation of the field-induced temperature change.

cond-mat.mtrl-sci↗

arXiv2014

Electric dipole sheets in BaTiO$_{3}$/BaZrO$_{3}$ superlattices

We investigate two-dimensional electric dipole sheets in the superlattice made of BaTiO$_{3}$ and BaZrO$_{3}$ using first-principles-based Monte-Carlo simulations and density functional calculations. Electric dipole domains and complex patterns are observed and the complex dipole structures with various symmetries (e.g. Pma2, Cmcm and Pmc2_{1}) are further confirmed by density functional calculations, which are found to be almost degenerate in energy with the ferroelectric ground state of the Amm2 symmetry, therefore strongly resembling magnetic sheets. More complex dipole patterns, including vortices and anti-vortices, are also observed, which may constitute the intermediate states that overcome the high energy barrier of different polarization orientations previously predicted by Lebedev\onlinecite{Lebedev2013}. We also show that such system possesses large electrostrictive effects that may be technologically important.

cond-mat.mtrl-sci↗