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Positive and negative electrocaloric effect in BaTiO3 in the presence of defect dipoles

Ma, Yang-Bin ; Grünebohm, Anna ; Meyer, Kai-Christian ; Albe, Karsten ; Xu, Bai-Xiang (2016)
Positive and negative electrocaloric effect in BaTiO3 in the presence of defect dipoles.
In: Physical Review B, 94 (9)
doi: 10.1103/PhysRevB.94.094113
Artikel, Bibliographie

Kurzbeschreibung (Abstract)

The influence of defect dipoles on the electrocaloric effect (ECE) in acceptor doped BaTiO3 is studied by means of lattice-based Monte-Carlo simulations using a Ginzburg-Landau type effective Hamiltonian. Oxygen vacancy-acceptor associates are described by fixed local dipoles with orientation parallel or antiparallel to the external field. By a combination of canonical and microcanonical simulations the ECE is directly evaluated. Our results reveal that in the case of antiparallel defect dipoles the ECE can be positive or negative depending on the dipole density. Moreover, a transition from a negative to positive ECE can be observed 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 in good qualitative agreement to those obtained by molecular dynamics simulations employing an ab initio based effective Hamiltonian. Finally, a modified electrocaloric cycle, which makes use of the negative ECE in the presence of defect dipoles, is proposed to enhance the cooling effect.

Typ des Eintrags: Artikel
Erschienen: 2016
Autor(en): Ma, Yang-Bin ; Grünebohm, Anna ; Meyer, Kai-Christian ; Albe, Karsten ; Xu, Bai-Xiang
Art des Eintrags: Bibliographie
Titel: Positive and negative electrocaloric effect in BaTiO3 in the presence of defect dipoles
Sprache: Englisch
Publikationsjahr: 29 September 2016
Titel der Zeitschrift, Zeitung oder Schriftenreihe: Physical Review B
Jahrgang/Volume einer Zeitschrift: 94
(Heft-)Nummer: 9
DOI: 10.1103/PhysRevB.94.094113
Kurzbeschreibung (Abstract):

The influence of defect dipoles on the electrocaloric effect (ECE) in acceptor doped BaTiO3 is studied by means of lattice-based Monte-Carlo simulations using a Ginzburg-Landau type effective Hamiltonian. Oxygen vacancy-acceptor associates are described by fixed local dipoles with orientation parallel or antiparallel to the external field. By a combination of canonical and microcanonical simulations the ECE is directly evaluated. Our results reveal that in the case of antiparallel defect dipoles the ECE can be positive or negative depending on the dipole density. Moreover, a transition from a negative to positive ECE can be observed 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 in good qualitative agreement to those obtained by molecular dynamics simulations employing an ab initio based effective Hamiltonian. Finally, a modified electrocaloric cycle, which makes use of the negative ECE in the presence of defect dipoles, is proposed to enhance the cooling effect.

Fachbereich(e)/-gebiet(e): 11 Fachbereich Material- und Geowissenschaften
11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft
11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Mechanik Funktionaler Materialien
11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Materialmodellierung
Zentrale Einrichtungen
Zentrale Einrichtungen > Hochschulrechenzentrum (HRZ)
Zentrale Einrichtungen > Hochschulrechenzentrum (HRZ) > Hochleistungsrechner
Hinterlegungsdatum: 30 Sep 2016 10:54
Letzte Änderung: 26 Jan 2024 09:21
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