DC electrical resistivity of Nb-Doped BaTiO3 and EPR measurements

Gillot, C.; Michenaud, Jean-Pierre; Maglione, Mario; Jannot, B.

doi:10.1016/0038-1098(92)90434-b

Cited by 63 publications

(36 citation statements)

References 12 publications

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“…This activation energy is quite compatible with resistivity and Hall measurements performed in BaTiO 3 single crystals. 43,44 This shows that the dielectric relaxation which induces the increased dielectric losses is connected to a motion of free charges. However, free charges alone cannot contribute to dielectric relaxation and electrical energy is to be exchanged between these charges and the dielectric lattice.…”

Section: Polaron Contribution To the Dielectric Permittivity Of Perovmentioning

confidence: 92%

Free charge localization and effective dielectric permittivity in oxides

Maglione

2016

J. Adv. Dielect.

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This review will deal with several types of free charge localization in oxides and their consequences on the effective dielectric spectra of such materials. The first one is the polaronic localization at the unit cell scale on residual impurities in ferroelectric networks. The second one is the collective localization of free charge at macroscopic interfaces like surfaces, electrodes and grain boundaries in ceramics. Polarons have been observed in many oxide perovskites mostly when cations having several stable electronic configurations are present. In manganites, the density of such polarons is so high as to drive a net lattice of interacting polarons. On the other hand, in ferroelectric materials like BaTiO 3 and LiNbO 3 , the density of polarons is usually very small but they can influence strongly the macroscopic conductivity. The contribution of such polarons to the dielectric spectra of ferroelectric materials is described. Even residual impurities as for example Iron can induce well-defined anomalies at very low temperatures. This is mostly resulting from the interaction between localized polarons and the highly polarizable ferroelectric network in which they are embedded. The case of such residual polarons in SrTiO 3 will be described in more detail, emphasizing the quantum polaron state at liquid helium temperatures. Recently, several nonferroelectric oxides have been shown to display giant effective dielectric permittivity. It is first shown that the frequency/temperature behavior of such parameters is very similar in very different compounds (donor-doped BaTiO 3 , CaCu 3 Ti 4 O 12 , LuFe 2 O 4 , Li-doped NiO, etc.). This similarity calls for a common origin of the giant dielectric permittivity in these compounds. A space charge localization at macroscopic interfaces can be the key for such extremely high dielectric permittivity.

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Section: Polaron Contribution To the Dielectric Permittivity Of Perovmentioning

confidence: 92%

Free charge localization and effective dielectric permittivity in oxides

Maglione

2016

J. Adv. Dielect.

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“…In unpolished TSSG and pure flux crystals, the peak near −90 • C are also distinct. The existence of the peaks and the overall σ − T characteristics are completely different from those of intentionally doped BaTiO 3 's [2][3][4][5]. As in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…On the other hand, recent theoretical developments have revealed the importance of the electronic interaction and the electron-ion coupling in ferroelectricity. The traces of such interactions have also been suggested through the electron conduction [2][3][4][5] and the mid-infrared absorption of doped ferroelectrics [6,7], which indicates that the electrical conduction leads to the elucidation of the new aspects of ferroelectricity.…”

Section: Introductionmentioning

confidence: 99%

“…The conductance of the ferroelectrics has however been studied by use of the thin films and the semiconducting bulk samples produced by chemical modifications [2][3][4][5]. In these studies a conduction anomaly in semiconducting ceramic ferroelectrics known as the positive temperature coefficient resistance (PTC) is shown to be a surface effect due to the grain boundaries [1,[8][9][10].…”

Section: Introductionmentioning

confidence: 99%

“…In the studies of electrical conduction of the bulk BaTiO 3 , chemically doped or photodoped samples have been measured [2][3][4][5][8][9][10], because undoped BaTiO 3 is insulating or semiinsulating. In the present paper, we study mainly the conductance of nominally pure stoichiometric BaTiO 3 single crystals at low electric field in the darkness.…”

Section: Introductionmentioning

confidence: 99%

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Spontaneous Emergence of Free Carrier at Phase Transitions of Insulating BaTiO₃ Single Crystals: Experimental Analyses

et al. 2006

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The conductance of BaTiO 3 and the relaxor single crystals is measured. Unlike conventional insulators, the stoichiometric crystals in which the conductance due to the impurities are rendered negligible exhibit an intrinsic conductance that is manifested as the sharp peaks at the phase transitions, and the peaks become evident with purity, and its values are nearly independent of the samples that are grown by the different methods and the conditions, whereas the conductance above T C depends critically on the samples. Especially, these findings are verified by the measurements of the current at constant voltages. These observations elucidate that the ferroelectrics posses a carrier generation mechanism, which has been invisible in semiconducting samples.

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A Multiple Structure‐Design Strategy towards Ultrathin Niobate Perovskite Nanosheets with Thickness‐Dependent Photocatalytic Hydrogen‐Evolution Performance

Zhou

Wen

Zhang

et al. 2017

Chemistry An Asian Journal

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Hydrogen production by catalytic water splitting using sunlight holds great promise for clean and sustainable energy source. Despite the efforts made in the past decades, challenges still exist in pursuing solid catalysts with light-harvesting capacity, large surface areas and efficient utilities of the photogenerated carrier, at the same time. Here, a multiple structure design strategy leading to highly enhanced photocatalytic performance on hydrogen production from water splitting in Dion-Jacobson perovskites KCa Na Nb O is described. Specifically, chemical doping (N/Nb ) of the parent oxides via ammoniation improved the ability of sunlight harvesting efficiently; subsequent liquid exfoliation of the doped perovskites yielded ultrathin [Ca Na Nb O ] nanosheets with greatly increased surface areas. Significantly, the maximum hydrogen evolution appears in the n=4 nanosheets, which suggests the most favorable thickness for charge separation in such perovskite-type catalysts. The optimized black N/Nb -[Ca NaNb O ] nanosheets show greatly enhanced photocatalytic performance, as high as 973 μmol h with Pt loading, on hydrogen evolution from water splitting. As a proof-of-concept, this work highlights the feasibility of combining various chemical strategies towards better catalysts and precise thickness control of two-dimensional materials.

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DC electrical resistivity of Nb-Doped BaTiO3 and EPR measurements

Cited by 63 publications

References 12 publications

Free charge localization and effective dielectric permittivity in oxides

Free charge localization and effective dielectric permittivity in oxides

Spontaneous Emergence of Free Carrier at Phase Transitions of Insulating BaTiO₃ Single Crystals: Experimental Analyses

A Multiple Structure‐Design Strategy towards Ultrathin Niobate Perovskite Nanosheets with Thickness‐Dependent Photocatalytic Hydrogen‐Evolution Performance

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DC electrical resistivity of Nb-Doped BaTiO3 and EPR measurements

Cited by 63 publications

References 12 publications

Free charge localization and effective dielectric permittivity in oxides

Free charge localization and effective dielectric permittivity in oxides

Spontaneous Emergence of Free Carrier at Phase Transitions of Insulating BaTiO3 Single Crystals: Experimental Analyses

A Multiple Structure‐Design Strategy towards Ultrathin Niobate Perovskite Nanosheets with Thickness‐Dependent Photocatalytic Hydrogen‐Evolution Performance

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Spontaneous Emergence of Free Carrier at Phase Transitions of Insulating BaTiO₃ Single Crystals: Experimental Analyses