arXiv subjects

Jordan A. Barr

Publications and source records attributed to Jordan A. Barr.

3 recordsLinked to original sources

arXiv2015

Elastocaloric response of PbTiO3 predicted from a first-principles effective Hamiltonian

A first-principles based effective Hamiltonian is used within a molecular dynamics simulation to study the elastocaloric effect in PbTiO3. It is found that the transition temperature is a linear function of uniaxial tensile stress. Negative temperature change is calculated, when the uniaxial tensile stress is switched off, as a function of initial temperature Delta-T(T_initial). It is predicted that the formation of domain structures under uniaxial tensile stress degrades the effectiveness of the elastocaloric effect.

cond-mat.mtrl-sci↗

arXiv2013

Direct molecular dynamics simulation of electrocaloric effect in BaTiO3

The electrocaloric effect (ECE) in BaTiO3 is simulated using two different first-principles based effective Hamiltonian molecular dynamics methods. The calculations are performed for a wide range of temperatures (30--900 K) and external electric fields (0--500 kV/cm). As expected, a large adiabatic temperature change, Delta-T, at the Curie temperature, T_C, is observed. It is found that for single crystals of pure BaTiO3, the temperature range where a large Delta-T is observed is narrow for small external electric fields (<50 kV/cm). Large fields (>100 kV/cm) may be required to broaden the effective temperature range. The effect of crystal anisotropy on the ECE Delta-T is also investigated. It is found that applying an external electric field along the [001] direction has a larger ECE than those along the [110] and [111] directions.

cond-mat.mtrl-sci↗

arXiv2012

Effective Hamiltonian Methods for Predicting the Electrocaloric Behavior of BaTiO3

The perovskite crystal BaTiO3 is modeled using a first-principles based effective Hamiltonian and molecular dynamics simulations are performed to estimate the pyroelectric response. The electrocaloric temperature change, \DeltaT, is calculated for different temperatures and externally applied electric fields. It is found that it is possible to achieve a large \DeltaT, around 5-6 K, for a relatively small electric field gradient, less than 100 kV/cm, if the applied fields have a small absolute magnitude.

cond-mat.mtrl-sci↗