Absorption Edge Anomalies in Polar Semiconductors and Dielectrics at Phase Transitions

Zametin, V. I.

doi:10.1002/pssb.2221240222

Cited by 63 publications

(18 citation statements)

References 26 publications

(12 reference statements)

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“…However, these small values of activation energy of ac conductivity have been attributed to the shallow trap controlled current conduction of the sample 31 because the band gap of PZ ceramic is as high as 3.93 eV. 34 The shallow trapped controlled conduction is created from the donor states as a possible consequence of oxygen vacancies, as…”

Section: ͑2͒mentioning

confidence: 99%

Slim P-E hysteresis loop and anomalous dielectric response in sol-gel derived antiferroelectric PbZrO3 thin films

Parui

Krupanidhi

2008

Journal of Applied Physics

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Sol-gel derived PbZrO3 (PZ) thin films have been deposited on Pt(111)∕Ti∕SiO2∕Si substrate and according to the pseudotetragonal symmetry of PZ, the relatively preferred (110)t oriented phase formation has been noticed. The room temperature P-E hysteresis loops have been observed to be slim by nature. The slim hysteresis loops are attributed to the [110]t directional antiparallel lattice motion of Pb ions and by the directionality of the applied electric field. Pure PZ formation has been characterized by the dielectric phase transition at 235°C and antiferroelectric P-E hysteresis loops at room temperature. Dielectric response has been characterized within a frequency domain of 100Hz–1MHz at various temperatures ranging from 40to350°C. Though frequency dispersion of dielectric behaves like a Maxwell–Wagner type of relaxation, ω2 dependency of ac conductivity indicates that there must be G-C equivalent circuit dominance at high frequency. The presence of trap charges in PZ has been determined by Arrhenius plots of ac conductivity. The temperature dependent n (calculated from the universal power law of ac conductivity) values indicate an anomalous behavior of the trapped charges. This anomaly has been explained by strongly and weakly correlated potential wells of trapped charges and their behavior on thermal activation. The dominance of circuit∕circuits resembling Maxwell–Wagner type has been investigated by logarithmic Nyquist plots at various temperatures and it has been justified that the dielectric dispersion is not from the actual Maxwell–Wagner-type response.

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Section: ͑2͒mentioning

confidence: 99%

Slim P-E hysteresis loop and anomalous dielectric response in sol-gel derived antiferroelectric PbZrO3 thin films

Parui

Krupanidhi

2008

Journal of Applied Physics

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“…After the insert of TO layer, the light absorption in the UV region was enhanced significantly, possibly due to the large optical density of TO compared to PTO, despite their similar band gap values. [ 26 ]…”

Section: Figurementioning

confidence: 99%

Enhanced Photoelectrochemical Performance by Interface Engineering in Ternary g‐C₃N₄/TiO₂/PbTiO₃ Films

Wang

Zheng

Weng

et al. 2020

Adv Materials Inter

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Ferroelectric materials recently rise as promising candidates in solar energy harvesting owing to their unconventional photophysics, such as above-bandgap photovoltage, [6] tunable photovoltaic outputs, and birefractive behaviors. [7] These unique properties stem from the centrosymmetry breaking and spontaneous polarization of ferroelectrics, which produces an internal field that drives the efficient separation of photocarriers. [8] PbTiO 3 (PTO), as a prototypical ferroelectric perovskite oxide, stands out as a potential material for PEC applications due to its robust room temperature ferroelectricity and huge polarization. [9] Also, noble-metal decoration or other semiconductors compositing were used to further improve the PEC performance of PTO. For example, Chao et al. utilized a hydrothermal method to synthesize Au island decorated single-domain PTO nanoplates, and the composite demonstrated an efficient photocatalytic degradation of RhB performance. [10] Lekha et al. engineered a series of PTO/LaCrO3 p-n junction through a two-step combustion process, and found that the optimal photocurrent density was 4.5 times larger than that of pure PTO photoelectrode. [11] Recently, metal-free polymeric semiconductor, graphitelike carbon nitride (g-C 3 N 4 ) has attracted much attention due to its moderate band gap of 2.7 eV and inherent chemical and thermal stability compared to transitional metal oxides and sulfide. [12] However, the high photocarrier recombination rate and poor quantum efficiency has driven the effort to construct various composite structures to alleviate these deficiencies of pure g-C 3 N 4 . [13] Xiao et al. fabricated a Z-scheme 0D g-C 3 N 4 particles/1D TO nanotube arrays heterostructure to promote charge carriers separation and transfer processes, thus improve the PEC water splitting ability. [14] Wang et al. prepared a nanostructured g-C 3 N 4 /BiVO 4 composite films, and the photocurrent density was approximately 15 times as that of BiVO 4 photoelectrode, which was ascribed to the formation of a type II heterostructure between g-C 3 N 4 and BiVO 4 . [15] In this study, we fabricated the polycrystalline PTO film by a sol-gel method, and the g-C 3 N 4 were than decorated on the surface of the PTO film through chemical vapor deposition method to improve the PEC performance. To further improve the PEC performance, a TO buffer layer was inserted between PTO and g-C 3 N 4 , which was widely used as electrons transport layer in solar cells. [16] The optimal photocurrent density of CN/TO/PTO photoelectrode was 4.5 times higher than that Polycrystalline ferroelectric PbTiO 3 (PTO) films deposited on transparent fluorine-doped tin oxide (FTO) glass have been proved to be a photocathode for photoelectrochemical (PEC) water splitting. However, the hitherto reported PEC performances remain inferior to meet the requirements for practical applications. Herein, it is reported that a compact TiO 2 (TO) buffer layer, inserted between PTO and g-C 3 N 4 (CN), improves significantly its PEC performance. The o...

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“…Trying to understand the origin of this discrepancy, it is worth noticing that the band gaps of PbTiO 3 and PbZrO 3 were not directly measured but extrapolated to 0 K. 93 The reported values strongly depend of the method and the choice of parameters used to extrapolate the high temperature data. 93 Since B1-WC with the exact exchange parameter A = 0.16 gives good structural and electronic properties for the cubic phases of the considered compounds, further, we have calculated the other structural and electronic properties of the cubic and tetragonal phases of BaTiO 3 and PbTiO 3 ͑see Table VI͒. The B1-WC electronic band structure of BaTiO 3 obtained from the Ti all-electron calculation is shown in Fig.…”

Section: B B1-wc Hybrid Functionalmentioning

confidence: 99%

Hybrid exchange-correlation functional for accurate prediction of the electronic and structural properties of ferroelectric oxides

et al. 2008

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Hybrid exchange-correlation functional for accurate prediction of the electronic anD structural properties of ferroelectric oxides. / D. I. Bilc; R. Orlando; R. Shaltaf; G. M. Rignanese; J. Íñiguez; Ph. Ghosez. -In: PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS. -ISSN 1098-ISSN -0121. -77:16(2008, pp. 165107-1-165107-13. Original Citation:Hybrid exchange-correlation functional for accurate prediction of the electronic anD structural properties of ferroelectric oxides. Published version:DOI:10.1103/PhysRevB.77.165107 Terms of use:Open Access (Article begins on next page) Anyone can freely access the full text of works made available as "Open Access". Works made available under a Creative Commons license can be used according to the terms and conditions of said license. Use of all other works requires consent of the right holder (author or publisher) if not exempted from copyright protection by the applicable law. Using a linear combination of atomic orbitals approach, we report a systematic comparison of various density functional theory ͑DFT͒ and hybrid exchange-correlation functionals for the prediction of the electronic and structural properties of prototypical ferroelectric oxides. It is found that none of the available functionals is able to provide, at the same time, accurate electronic and structural properties of the cubic and tetragonal phases of BaTiO 3 and PbTiO 3 . Some, although not all, usual DFT functionals predict the structure with acceptable accuracy, but always underestimate the electronic band gaps. Conversely, common hybrid functionals yield an improved description of the band gaps, but overestimate the volume and atomic distortions associated with ferroelectricity, giving rise to an unacceptably large c / a ratio for the tetragonal phases of both compounds. This supertetragonality is found to be induced mainly by the exchange energy corresponding to the generalized gradient approximation ͑GGA͒ and, to a lesser extent, by the exact exchange term of the hybrid functional. We thus propose an alternative functional that mixes exact exchange with the recently proposed GGA of Wu and Cohen ͓Phys. Rev. B 73, 235116 ͑2006͔͒ which, for solids, improves over the treatment of exchange of the most usual GGA's. The new functional renders an accurate description of both the structural and electronic properties of typical ferroelectric oxides. Availability: This is the author's manuscript

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Absorption Edge Anomalies in Polar Semiconductors and Dielectrics at Phase Transitions

Cited by 63 publications

References 26 publications

Slim P-E hysteresis loop and anomalous dielectric response in sol-gel derived antiferroelectric PbZrO3 thin films

Slim P-E hysteresis loop and anomalous dielectric response in sol-gel derived antiferroelectric PbZrO3 thin films

Enhanced Photoelectrochemical Performance by Interface Engineering in Ternary g‐C₃N₄/TiO₂/PbTiO₃ Films

Hybrid exchange-correlation functional for accurate prediction of the electronic and structural properties of ferroelectric oxides

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Absorption Edge Anomalies in Polar Semiconductors and Dielectrics at Phase Transitions

Cited by 63 publications

References 26 publications

Slim P-E hysteresis loop and anomalous dielectric response in sol-gel derived antiferroelectric PbZrO3 thin films

Slim P-E hysteresis loop and anomalous dielectric response in sol-gel derived antiferroelectric PbZrO3 thin films

Enhanced Photoelectrochemical Performance by Interface Engineering in Ternary g‐C3N4/TiO2/PbTiO3 Films

Hybrid exchange-correlation functional for accurate prediction of the electronic and structural properties of ferroelectric oxides

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Enhanced Photoelectrochemical Performance by Interface Engineering in Ternary g‐C₃N₄/TiO₂/PbTiO₃ Films