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Article: Coexistence of polar displacements and conduction in doped ferroelectrics: An ab initio comparative study

TitleCoexistence of polar displacements and conduction in doped ferroelectrics: An ab initio comparative study
Authors
KeywordsBarium titanate
Calculations
Electrons
Metals
Niobium compounds
Issue Date2019
PublisherAmerican Physical Society. The Journal's web site is located at https://journals.aps.org/prmaterials/
Citation
Physical Review Materials, 2019, v. 3, p. article no. 054405 How to Cite?
AbstractPolar metals are rare because free carriers in metals screen electrostatic potential and eliminate internal dipoles. Degenerate doped ferroelectrics may create an approximate polar metallic phase. We use first-principles calculations to investigate n-doped LiNbO 3 -type oxides (LiNbO3 as the prototype) and compare to widely studied perovskite oxides (BaTiO 3 as the prototype). In the rigid-band approximation, substantial polar displacements in n-doped LiNbO 3 persist even at 0.3 e/f.u. (≃1021cm- 3 ), while polar displacements in n-doped BaTiO3 quickly get suppressed and completely vanish at 0.1 e/f.u. Furthermore, in n-doped LiNbO3, Li-O displacements decay more slowly than Nb-O displacements, while in n-doped BaTiO 3 , Ba-O and Ti-O displacements decay approximately at the same rate. Supercell calculations that use oxygen vacancies as electron donors support the main results from the rigid-band approximation and provide more detailed charge distributions. Substantial cation displacements are observed throughout LiNbO 3 -δ(δ=4.2%), while cation displacements in BaTiO 3 -δ(δ=4.2%) are almost completely suppressed. We find that conduction electrons in LiNbO3-δ are not as uniformly distributed as in BaTiO 3 -δ, implying that the rigid-band approximation should be used with caution in simulating electron-doped LiNbO 3 -type oxides. Our work shows that polar distortions and conduction can coexist in a wide range of electron concentration in n-doped LiNbO 3 , which is a practical approach to generating an approximate polar metallic phase. Combining doped ferroelectrics and doped semiconductors may create new functions for devices. © 2019 American Physical Society.
Persistent Identifierhttp://hdl.handle.net/10722/272248
ISSN
2020 Impact Factor: 3.989
2020 SCImago Journal Rankings: 1.439
ISI Accession Number ID

 

DC FieldValueLanguage
dc.contributor.authorXIA, C-
dc.contributor.authorChen, Y-
dc.contributor.authorChen, H-
dc.date.accessioned2019-07-20T10:38:34Z-
dc.date.available2019-07-20T10:38:34Z-
dc.date.issued2019-
dc.identifier.citationPhysical Review Materials, 2019, v. 3, p. article no. 054405-
dc.identifier.issn2475-9953-
dc.identifier.urihttp://hdl.handle.net/10722/272248-
dc.description.abstractPolar metals are rare because free carriers in metals screen electrostatic potential and eliminate internal dipoles. Degenerate doped ferroelectrics may create an approximate polar metallic phase. We use first-principles calculations to investigate n-doped LiNbO 3 -type oxides (LiNbO3 as the prototype) and compare to widely studied perovskite oxides (BaTiO 3 as the prototype). In the rigid-band approximation, substantial polar displacements in n-doped LiNbO 3 persist even at 0.3 e/f.u. (≃1021cm- 3 ), while polar displacements in n-doped BaTiO3 quickly get suppressed and completely vanish at 0.1 e/f.u. Furthermore, in n-doped LiNbO3, Li-O displacements decay more slowly than Nb-O displacements, while in n-doped BaTiO 3 , Ba-O and Ti-O displacements decay approximately at the same rate. Supercell calculations that use oxygen vacancies as electron donors support the main results from the rigid-band approximation and provide more detailed charge distributions. Substantial cation displacements are observed throughout LiNbO 3 -δ(δ=4.2%), while cation displacements in BaTiO 3 -δ(δ=4.2%) are almost completely suppressed. We find that conduction electrons in LiNbO3-δ are not as uniformly distributed as in BaTiO 3 -δ, implying that the rigid-band approximation should be used with caution in simulating electron-doped LiNbO 3 -type oxides. Our work shows that polar distortions and conduction can coexist in a wide range of electron concentration in n-doped LiNbO 3 , which is a practical approach to generating an approximate polar metallic phase. Combining doped ferroelectrics and doped semiconductors may create new functions for devices. © 2019 American Physical Society.-
dc.languageeng-
dc.publisherAmerican Physical Society. The Journal's web site is located at https://journals.aps.org/prmaterials/-
dc.relation.ispartofPhysical Review Materials-
dc.rightsPhysical Review Materials. Copyright © American Physical Society.-
dc.rightsCopyright [2019] by The American Physical Society. This article is available online at [http://dx.doi.org/10.1103/PhysRevMaterials.3.054405].-
dc.subjectBarium titanate-
dc.subjectCalculations-
dc.subjectElectrons-
dc.subjectMetals-
dc.subjectNiobium compounds-
dc.titleCoexistence of polar displacements and conduction in doped ferroelectrics: An ab initio comparative study-
dc.typeArticle-
dc.identifier.emailChen, Y: yuechen@hku.hk-
dc.identifier.authorityChen, Y=rp01925-
dc.description.naturepublished_or_final_version-
dc.identifier.doi10.1103/PhysRevMaterials.3.054405-
dc.identifier.scopuseid_2-s2.0-85065995244-
dc.identifier.hkuros298978-
dc.identifier.volume3-
dc.identifier.spagearticle no. 054405-
dc.identifier.epagearticle no. 054405-
dc.identifier.isiWOS:000468237200002-
dc.publisher.placeUnited States-
dc.identifier.issnl2475-9953-

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