Coexistence of ferroelectricity and metallicity in M-doped BaTiO3 (M = Al, V, Cr, Fe, Ni, and Nb): First-principles study

Li, Gang; He, Chen; Xiong, Ying; Zou, Zhi; Liu, Yulin; Chen, Qilai; Zhang, Wanli; Yan, Shaoan; Xiao, Yongguang; Tang, Minghua; Li, Zheng

doi:10.1016/j.mtcomm.2021.102394

Cited by 6 publications

(3 citation statements)

References 47 publications

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“…24 Surprisingly, some studies found that small hole doping unexpectedly enhances the polarization in BaTiO 3 . 26,27 Recently, Cao et al proposed 28 that hole doping plays a key role in the stability of polar phases in HfO 2 , and using the virtual crystal approximation claimed to stabilize the f-phase even at sufficiently large La doping concentrations. However, the remanent polarization of doped HfO 2 films usually shows a trend of increase first and then decrease within a small doping range.…”

Section: Introductionmentioning

confidence: 99%

Charge-compensated co-doping stabilizes robust hafnium oxide ferroelectricity

Li,

Liu,

Yan

et al. 2024

J. Mater. Chem. C

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Section: Introductionmentioning

confidence: 99%

Charge-compensated co-doping stabilizes robust hafnium oxide ferroelectricity

Li,

Liu,

Yan

et al. 2024

J. Mater. Chem. C

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“…Theoretical insights suggest that the persistence of polar distortion is linked to the incomplete screening of Coulomb forces within this concentration range 33 . Other interaction mechanisms also include the metascreening effect and chemical bonding, which anomalously enhance the ferroelectricity of perovskites with carrier doping [34][35][36] . Recent studies have realized the crucial role played by holes introduced by dopants 37 or interface engineering 38 in stabilizing f-phase HfO2.…”

Section: Introductionmentioning

confidence: 99%

Universal insights into the origin of ferroelectricity in doped hafnia

Tang,

Li,

Yan

et al. 2024

Preprint

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Although doping stands out as a crucial method for inducing ferroelectricity in hafnia films, the mechanisms behind it remains controversial. Notably, the carriers introduced by heterovalent dopants have been largely overlooked. Here, through first-principles studies, we elucidate the key role played by the rich phase transition mechanism under carrier doping in understanding the origin of hafnia ferroelectricity. Electron doping orchestrates a metastable polar phase to stable antipolar phase transformation, driven by strong screening effects and the decay of nonpolar covalent bonds, resulting in the rarity of n-type dopants. Conversely, a delicate balanced interplay of weak screening effects and strengthened polar covalent bonds drives hole maintains robust ferroelectricity. However, the hole distribution pattern markedly affects the total energy difference across phases, culminating in a striking ground-state phase transition from nonpolar monoclinic phase to polar orthorhombic phase to nonpolar cube phase as the hole concentration increases. This phase transition is consistent with the variation trend of the highest phase fraction in hafnia films with the p-type dopants concentration. In addition, the thickness of hafnia ferroelectric films is easily stabilized on the 1 nm, unlike perovskite ferroelectrics, due to the hole enhanced polar distortion. Our theoretical analyses seamlessly align with experimental measurements, offering innovative perspectives for the preparation of robust hafnia-based ferroelectricity films through doping or interface engineering.

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“…at the surface is of the utmost importance for this reaction. Hence, the surface plays the role of the "interface" for the system bulk/environment [14,[16][17][18]. The main share of the investigation concerning the transformation of dielectric barium titanate into a metal was conducted via samples, which were quenched following thermal reduction to room temperature before electrodes were deposited on the reduced surface in order to investigate the electrical transport phenomena.…”

Section: Introductionmentioning

confidence: 99%

An Operando Study of the Thermal Reduction of BaTiO3 Crystals: The Nature of the Insulator–Metal Transition of the Surface Layer

Rodenbücher,

Bihlmayer,

Korte

et al. 2023

Crystals

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The insulator-to-metal transition upon the thermal reduction of perovskites is a well-known yet not completely understood phenomenon. By combining different surface-sensitive analysis techniques, we analyze the electronic transport properties, electronic structure, and chemical composition during the annealing and cooling of high-quality BaTiO3 single crystals under ultra-high-vacuum conditions. Our results reveal that dislocations in the surface layer of the crystal play a decisive role as they serve as easy reduction sites. In this way, conducting filaments evolve and allow for turning a macroscopic crystal into a state of metallic conductivity upon reduction, although only an extremely small amount of oxygen is released. After annealing at high temperatures, a valence change of the Ti ions in the surface layer occurs, which becomes pronounced upon the quenching of the crystal. This shows that the reduction-induced insulator-to-metal transition is a highly dynamic non-equilibrium process in which resegregation effects in the surface layer take place. Upon cooling to the ferroelectric phase, the metallicity can be preserved, creating a “ferroelectric metal.” Through a nanoscale analysis of the local conductivity and piezoelectricity, we submit that this phenomenon is not a bulk effect but originates from the simultaneous existence of dislocation-based metallic filaments and piezoelectrically active areas, which are spatially separated.

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Coexistence of ferroelectricity and metallicity in M-doped BaTiO3 (M = Al, V, Cr, Fe, Ni, and Nb): First-principles study

Cited by 6 publications

References 47 publications

Charge-compensated co-doping stabilizes robust hafnium oxide ferroelectricity

Charge-compensated co-doping stabilizes robust hafnium oxide ferroelectricity

Universal insights into the origin of ferroelectricity in doped hafnia

An Operando Study of the Thermal Reduction of BaTiO3 Crystals: The Nature of the Insulator–Metal Transition of the Surface Layer

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